Felson's Principles of Chest Roentgenology, Third Edition ( PDFDrive )

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FELSON’S PRINCIPLES OF CHEST ROENTGENOLOGY ISBN-13: 978-1-4160-2923-6
ISBN-10: 1-4160-2923-0
Copyright © 2007 by Saunders, an imprint of Elsevier Inc.
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Previous editions copyrighted 1999, 1965 by Saunders
Library of Congress Cataloging-in-Publication Data
Goodman, Lawrence R. (Lawrence Roger)
Felson’s principles of chest roentgenology.— 3rd. ed. / Lawrence R. Goodman. 
p.; cm.
ISBN-13: 978-1-4160-2923-6
ISBN-10: 1-4160-2923-0
1. Chest—Radiography. I. Felson, Benjamin. II. Title. III. Title: Principles of chest roentgenology.
[DNLM: 1. Radiography, Thoracic—Programmed Instruction. WF 18.2 G653f 2007]
RC941.G56 2007
617.5′407572—dc22
2006051198
Acquisitions Editor: Todd Hummel
Publishing Services Manager: Tina Rebane
Project Manager: Linda Lewis Grigg
Design Direction: Steven Stave
Printed in USA
Last digit is the print number: 9 8 7 6 5 4 3 2 1
Notice
Neither the publisher nor the author assumes any responsibility for any loss or injury and/or
damage to persons or property arising out of or related to any use of the material contained in 
this book. It is the responsibility of the treating practitioner, relying on independent expertise 
and knowledge of the patient, to determine the best treatment and method of application for 
the patient.
The Publisher
To my late parents,
Martha and Sidney Goodman,
for years of support, encouragement, and love
and to my wife, Hannah,
and Roy, Julie, Sarah, and Noah
PREFACE
In speaking to students about the second edition of Felson’s Principles of Chest Roentgenology,
I found that almost all of them wanted more unknown cases and more computed tomogra-
phy. Yet they wanted the text to stay short and manageable. With the addition of a CD to
this third edition, the original text keeps its style, density, and length, while new material is
on the CD as an option.
Cases! Cases! Cases! “We want more unknown cases.” I agree. Adding a CD made it easier
to provide more cases without making the text too long. The CD also provides some interactive
possibilities. The extra cases have been divided into “structured unknowns”—-similar to
the “Quiz: A Dozen Great Cases “ in the text—-and “real world unknowns”—-with just history
provided (sink or swim).
Interstitial Lung Disease. This topic drives everyone crazy. In “Interstitial Lung Disease: 
A Picture Book,” there are brief, pictured representations of various patterns. 
More CT. There is a new chapter, “Chest CT: Putting It Together.” And more CT images have
been added to the text and quizzes.
Rib Notching. In Felson’s original edition, the last chapter was “The Many Causes of Rib
Notching.” This always seemed to me an extra chapter he threw in at the end to bulk up the
book. It was quite good, however, and is now available on the CD. 
Oral Boards in Chest. This section has been added to the CD to give advanced radiology
residents a “taste” of the oral boards.
Thanks: Again, thanks to Ms. Sylvia Bartz, my senior administrative assistant, for her won-
derful support and good counsel and to my wife, Hannah, for her encouragement and com-
puter savvy. Thanks also to Professor Lorenzo Bonomo of the Universitá Cattolica in Rome.
He provided warm hospitality and a quiet place for me to work on this third edition of
Felson’s Principles of Chest Roentgenology.
Lawrence R. Goodman
CREDITS
Figures
2-11 Dr. Andrew Taylor Medical College of Wisconsin, Milwaukee
2-12 Dr. Kiran Sagar Medical College of Wisconsin, Milwaukee
6-3 Dr. E. Martinez Prescott, Arizona
7-3A Ms. Ann Gorman Medical College of Wisconsin, Milwaukee
10-9 Dr. Melissa Wein Medical College of Wisconsin, Milwaukee
11-10 and 11-17 Dr. Sanford Rubin University of Texas, Galveston
11-4D Dr. Francisco Quiroz Medical College of Wisconsin, Milwaukee
12-12 The late Dr. Wylie Dodds Medical College of Wisconsin, Milwaukee
12-14 Dr. Emanuelle Fedrea Universitá delgi Studi di Milano, Milan, Italy
Q-12 Dr. Timothy Klostermeier Wilmington, Ohio
Board Review C-5 Lorenzo Bonomo Universitá Cattolica, Rome, Italy
S-39 Internet Scientific www.ispub.com
Publications
Cartoons
Pages
105 Beetle Bailey Copyright King Features Syndicate
11, 43, and 65 Julie Goodman, MLA Brooklyn, New York
CD “Glossary of Terms for CT Radiology, with permission
of the Lungs: 
Recommendations of the 
Nomenclature Committee 
of the Fleischner Society,” 
CD “Glossary of Terms for Am J Roentgenol, with permission
Thoracic Radiology: 
Recommendations of the 
Nomenclature Committee 
of the Fleischner Society,” 
Thanks to Messrs. Stanton and Barry Himelhoch (photographers) and Mr. Robert Fenn
(illustrator) of Medical Center Graphics, Milwaukee, Wisconsin.
INSTRUCTIONS
Most of you are familiar with programmed learning. The numbered frames on the left side
of each page require a response. Questions are designed, in most instances, to help you
make the correct response: The answer is often made clear by the frame itself or by what
you have learned in earlier frames. Answer by filling in the blanks or underlining where
there are multiple choices. The answer to each frame will be found on the right side of the
page. Use the mask, on the back cover of the book, to hide answers to the frame. We prefer
you to write your answers in ink so that your friends will have to buy their own copies.
It is not essential that your answers be identical to ours, so long as the meaning is the same.
If you miss an answer, reread the frame so that you can be better prepared for what is to
come. It is okay to cheat by looking at the answers first, since it’s your money and time.
Because your concentrated attention is required, we suggest that you set a limit of an hour,
at most, of consecutive study.
At the end of each chapter is a Review Section summarizing the most important concepts.
Don’t skip them. “A Dozen Great Cases,” the quiz that follows the last chapter, contains
carefully selected x-rays that allow you to apply your new knowledge. If you don’t do well,
blame us. I hope our attempts at humor and informality make the learning process pleasant
and relaxing.
After you finish the text, there are supplemental chapters, additional unknowns, and a board
review on a CD.
Before going to Chapter 1, try the samples below.
1
This text is based on the reader’s participation.
(a) Mark Twain once said, “It is better to keep your mouth
shut and appear [stupid/smart] than to open it and
________________________.”
(b) Lee Rogers, MD, once said, “Don’t let the fear of being
[right/wrong] interfere with the joy of being __________.”
(c) We expect you to adopt philosophy [a/b]. 
2
Understanding the anatomy and the radiographic signs are the
keys to reading x-rays.
(a) “You’d be surprised how much you observe by ________
________________” said Lawrence (Yogi) Berra.
(b) “You only see what you ______________________,” says
Lawrence (Larry) Goodman, MD.
(c) This book was written based on assumption [a/b]. 
1
(a) stupid 
remove all doubt
(b) wrong 
right
(c) b
2
(a) watching
(b) know
(c) b (It’s my book!)
COMPACT DISK
CONTENTS
A CD is included with this edition to provide additional material with-
out interfering with the basic flow of the original text. When you finish
the text, take a look at the CD.
MORE UNKNOWN CASES
A. Challenging Cases: Structured like A Dozen Great Cases Quiz
B. Sink orSwim: Brief history only, like the real world
Supplemental CHAPTER 1: SEGMENTAL ANATOMY
This is revised Chapter 5 of the second edition of Principles of
Chest Roentgenology. Many people, including myself, thought
it was more detailed than needed. It is here for those of you
who are interested in more detail. 
Supplemental CHAPTER 2: INTERSTITIAL LUNG DISEASE FOR
THE NOVICE
Using a series of pictures, x-rays, and CT scans, this is a pictorial
explanation of honeycombing, the reticular pattern, and the
nodular patterns, etc.
Supplemental CHAPTER 3: THE MANY CAUSES OF RIB NOTCHING
This chapter was in the first edition of Principles of Chest
Roentgenology but was dropped from the second edition. It is
more than you need to know, but interesting. Try it if you have
time.
CHEST RADIOLOGY MOCK ORAL BOARDS
This a chance for senior radiology residents to try their hands
at some typical cases presented at the oral boards with a clock
ticking in the background. The only things that are missing are
tachycardia (yours) and an examiner sitting behind you, offering
you no feedback. Give it a shot. (Note: Current boards may
present more cardiac material than is presented here.)
“Glossary of Terms for CT of the Lungs: Recommendations
of the Nomenclature Committee of the Fleischner Society”
“Glossary of Terms for Thoracic Radiology: Recommendations
of the Nomenclature Committee of the Fleischner Society”
The CD is bound in the back of the book.
1
ONE
THE RADIOGRAPHIC
EXAMINATION
The chest x-ray and computed tomography (CT) are part of every physician’s practice. You
should have a basic understanding of the anatomy and pathology visible on the images. 
In just 12 short, interactive (and occasionally humorous) chapters, you will learn 
a systematic approach to reading the normal anatomy of the thorax and the basic patterns
of lung disease.
1
Let’s start with the standard frontal view of the chest, 
the posteroanterior (PA) radiograph, or the “PA chest.” 
The term posterior/anterior refers to the direction of the 
x-ray beam, which in this case traverses the patient 
from _______________ to _______________.
2
By convention, the routine frontal view is taken with the patient
upright and in full inspiration. The x-ray beam is horizontal, 
and the x-ray tube is 6 feet from the film or detector. This is
what you get when you order a _______________ view.
1
posterior (back); anterior
(front)
2
posteroanterior or “PA
chest”
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2 Felson’s Principles of Chest Roentgenology
FIGURE 1-1 A
FIGURE 1-1 B
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One • The Radiographic Examination 3
3
The PA view is taken at a distance of ____ feet to reduce magni-
fication and enhance sharpness. Placing the part to be x-rayed
close to the x-ray cassette (film receptor) also reduces magnifi-
cation and increases sharpness. See for yourself: Place your
hand, palm down, 3 or 4 inches from a desktop, preferably under
a desk lamp (bulb type). Observe the shadow.
(a) Flex your middle finger only. Its shadow gets [wider/
narrower] and appears [sharper/less sharp]. That finger
also appears foreshortened.
(b) If the light source (i.e., x-ray tube) moves further away,
magnification [increases/decreases], and the margins
become [sharper/less sharp].
4
To reduce the magnification and increase image sharpness, 
the chest should be as [close to/far from] the x-ray cassette 
as possible, and the x-ray tube should be as [close to/far from]
the cassette as practical.
5
The anteroposterior (AP) view is usually made with a
portable x-ray unit on very sick patients, who are unable to
stand, and on infants. The patient is supine or sitting in bed.
In this instance, the x-ray beam passes through the patient
from ______________ to _____________.
3
6
(a) narrower (less mag-
nification); sharper
(b) decreases; sharper
4
close to; far from
5
anterior; posterior
The AP view is taken supine or sitting rather than prone because it is less awk-
ward than a PA view for a sick patient, and an infant usually squawks less
when he or she can see what’s happening.
6
Because portable x-ray units are less powerful than regular units
are, and because space is tight at the bedside, AP views are 
usually taken at shorter x-ray tube-to-film (receptor) distance.
Compared with the PA radiograph, the AP radiograph has
[greater/less] magnification, and the anatomy appears [more/less]
sharp. The heart is an anterior structure. It would seem larger
on a(n) [AP/PA] image. Why? _______________.
6
greater; less; AP
The heart is further from
detector (film)
The PA upright is preferred to the AP supine view because (1) there is less magnifi-
cation; (2) the image is sharper; (3) the erect patient inspires more deeply, showing
more lung; and (4) pleural air and fluid are easier to detect on the erect film.
7
Figures 1-1A and 1-1B are two films of the same patient, one AP
and one PA. Which is the PA? How did you decide? _________.
7
Figure 1-1A is the PA
Sharper edges, less
magnification, deeper
inspiration
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4 Felson’s Principles of Chest Roentgenology
FIGURE 1-2 A
FIGURE 1-2 B
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One • The Radiographic Examination 5
8
The other routine view is the lateral. By convention, the 
left side of the chest is held against the x-ray cassette. This 
is called a ________________ view. Similar to the PA view, it is
also taken at ________________ feet.
8
left lateral
6
Frontal radiographs, AP or PA, are viewed as if you were facing the patient. 
In Figure 1-2A, and in all x-rays, the patient’s left is to your right. The heart is on
the left. Right?
If we were consistent, we would call it a right-left lateral, but “a foolish 
consistency is the hobgoblin of little minds” (Emerson). We just call it a 
lateral view.
9
It is often difficult to detect a lesion located behind the 
heart, near the mediastinum, or near the diaphragm on the 
PA view. The _____________ view generally shows such a lesion,
so we use it routinely.
9
lateral
Figures 1-2A and 1-2B. The nodule, superimposed on the heart, is easily seen on
the lateral view. On the frontal (PA) view, it is hard to see along the left heart
border. (Figure 1-2B, metallic artifact = pajama snap; Figure 1-2A and 1-2B, linear
artifact = intravenous catheter in superior vena cava.)
10
On the lateral, which is routinely taken with the [right/left] side
against the cassette, a right-sided nodule appears [larger/smaller]
than an identical left-sided nodule.
10
left
larger (magnified)
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6 Felson’s Principles of Chest Roentgenology
FIGURE 1-3 A
FIGURE 1-3 B
FIGURE 1-3 C
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One • The Radiographic Examination 7
11
In Figure 1-3A, the patient is in the right anterior oblique position.
His [left/right] chest is against the cassette, and the radiograph
is taken in the [AP/PA] direction.
12
When a patient turns from the straight PA to the right anterior
oblique position, different anatomic structures move in different
directions. In the right anterior oblique, the left pectoralis
muscle or breast (anterior structure) moves [medially/laterally],
and the left scapula (posterior structure) moves [medially/
laterally], relative to the thorax. The opposite occurs in the left
anterior oblique.
13
Oblique views can help us localize lesions and eliminate 
superimposed structures. Figure 1-3B is a PA radiograph 
showing a calcified (white) mass over the upper thorax on 
the patient’s [left/right]. In Figure 1-3C, in the right anterior
oblique, the mass moves [medially/laterally], relative to the
thorax. It must be located [anteriorly/posteriorly].
11
right
PA
12
laterally
medially
13
left
laterally
anteriorly
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8 Felson’s Principles of Chest Roentgenology
FIGURE 1-4 A
FIGURE 1-4 B
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One • The Radiographic Examination 9
14
What other views are there? Free fluid inthe pleural cavity 
is affected by gravity. Fluid gravitates toward the diaphragm
when the patient is [erect/supine], toward the back when 
the patient is [erect/supine], and toward the lateral aspect 
of the dependent thorax when the patient lies on his or 
her ________________ in the lateral decubitus position.
[Decubitus = lying down. Lateral decubitus = lying on the side. 
(I looked it up.)]
15
Return to Figure 1-1A. The [left/right] diaphragm is higher. 
This is normal. Now, in Figure 1-4A, the [left/right] diaphragm
appears higher. This is [normal/abnormal]. Gravity can help 
us find the cause.
16
Figure 1-4B is taken in the __________ position. The [left/right]
side is down. The x-ray beam is parallel to the x-ray table. There 
is now a white band between the left ribs and the ___________.
This is due to ________________.
Congratulations! This is your first x-ray diagnosis. The left
diaphragm appears high because there is fluid between the
lung base and the diaphragm.
14
erect
supine
side
15
right
left
abnormal
16
decubitus; left
lung
pleural effusion
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10 Felson’s Principles of Chest Roentgenology
FIGURE 1-5
FIGURE 1-6
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One • The Radiographic Examination 11
17
Intrapleural fluid falls with gravity, whereas intrapleural 
air ___________. The ideal position to diagnose a pneumothorax
(intrapleural air) is [erect/supine]. If you suspect a left 
pneumothorax in a patient, who can’t stand or sit, a lateral
decubitus film with the [left/right] side down is helpful. This is
called the ____________ position.
17
rises
erect
right
right lateral decubitus
Figure 1-5 shows a pneumothorax in the erect position (arrow delineates edge 
of lung). Figure 1-6, in a different patient, shows air between the lung and the left
ribs in the right lateral decubitus position.
18
The normal chest film is always made on [inspiration/expiration].
On expiration, the lung markings become more crowded. There
is less air in the lung, so the lung appears [whiter/blacker]. The
heart, which sits on the diaphragm, is elevated and appears
[larger/smaller].
18
inspiration
whiter
larger
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12 Felson’s Principles of Chest Roentgenology
FIGURE 1-7 A
FIGURE 1-7 B
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One • The Radiographic Examination 13
19
Figures 1-7A and 1-7B are PA radiographs of the same patient at
the same time. One is an inspiration and one is an expiration.
The diaphragms are higher in [Figure 1-7A/Figure 1-7B]. The
lungs appear blacker in [Figure 1-7A/Figure 1-7B]. The heart and
vessels appear bigger in [Figure 1-7A/Figure 1-7B]. Therefore,
[Figure 1-7A/Figure 1-7B] is an expiration.
19
Figure 1-7A
Figure 1-7B
Figure 1-7A
Figure 1-7A
Potential Pitfall: Expiratory films and AP supine films make the heart and 
vessels appear larger and the lungs whiter compared with a PA inspiratory film.
These changes may simulate disease.
What causes the x-ray film to be black or white? An unexposed x-ray film is housed
in a lightproof cassette, sandwiched between two phosphorescent screens. X-rays
hit the phosphorescent screens, the screens give off light, and the light exposes the
film. Heavy light exposure (e.g., through radiolucent lung) precipitates much
silver, which causes the film to be black. Little light exposure (e.g., through radio-
dense bone) precipitates little silver, which causes the film to be white. Film is now
being replaced by sophisticated digital receptors that offer many advantages; how-
ever, the basic image formation remains the same. Digital data are more flexible;
data can be transmitted, stored, and processed to alter contrast and brightness.
(More technical stuff is in Chapter 6—try to resist peeking.)
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14 Felson’s Principles of Chest Roentgenology
FIGURE 1-8 A
FIGURE 1-8 B
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One • The Radiographic Examination 15
20
Expiratory films can be used to one’s advantage. An expiratory
film can be used to detect focal air trapping from asymmetrical
emphysema or a partial bronchial obstruction that impedes 
airflow on expiration (air trapping). Because the air in the
obstructed bronchus cannot be expelled readily, that lung 
(or lobe) remains [inflated/deflated] on expiration, while the
rest of the lung ____________, normally.
21
On expiration with unilateral air trapping, a normal deflated
lung appears [whiter/blacker/unchanged], whereas an obstructed
lung appears [white/blacker/unchanged].
20
inflated
deflates
21
whiter
unchanged (remains
black)
In Figure 1-8A, the right lung is slightly blacker than the left lung. In Figure 1-8B,
an expiratory film, the left deflates normally and gets whiter, while the right
remains inflated and black. This was due to air trapping behind an aspirated
foreign body.
Clinical Pearl: If you hear a unilateral wheeze, order an expiratory film to look
for air trapping.
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16 Felson’s Principles of Chest Roentgenology
FIGURE 1-9 A-F
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One • The Radiographic Examination 17
22
An expiratory x-ray may accentuate a small pneumothorax. 
On expiration, the deflated lung appears [whiter/blacker] 
compared with the black intrapleural air, and the fixed amount
of intrapleural air is relatively [larger/smaller] in the smaller
hemithorax. Logical? Yes. Helpful? Seldom!
23
Let’s review the various radiographic positions. What views are
illustrated in Figure 1-9A-F?
A. ____________ D. ___________
B. ____________ E. ___________
C. ____________ F. ___________
22
whiter
larger
23
A. PA
B. lateral
C. right anterior oblique
D. AP
E. AP supine
F. right lateral decubitus
Two older techniques, the apical lordotic position and tomography (laminography),
were used to display areas obscured by overlapping structures. The apical lordotic
radiograph is a frontal view taken with the x-ray beam angled upward to project
the clavicles above the lung apex to display disease hidden behind the clavicles.
Tomography is a complex technique that uses an x-ray tube and cassette that move
in opposite directions, keeping only the area of interest in focus. Both techniques
have been largely replaced by better quality chest radiographs and computed
tomography (CT)—two fewer things you have to learn!
24
All techniques discussed so far produce static images—
a subsecond snapshot of the thorax. Fluoroscopy, which is a 
real-time x-ray viewed on a video monitor, provides informa-
tion about moving organs. Examples include motion of the
___________ during respiration and left ventricular ___________
during systole. During fluoroscopy, the patient can be turned
obliquely, to eliminate _____________ of structures.
24
diaphragm or chest wall
contraction
overlapping (superior
position
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18 Felson’s Principles of Chest Roentgenology
FIGURE 1-10
FIGURE 1-11
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One • The Radiographic Examination 19
25
Differential absorption and penetration of the x-ray photons
create the x-ray image. [Direct/scattered] radiation exposes the
film randomly, causing a background fog (loss of contrast),
rather than useful information. In Figure 1-10, the image is formed
by _____________ x-rays and degraded by ____________ x-rays.
26
Bone absorbs [more/less] radiation, and air absorbs
[more/less] radiation. Bone is said to be radiodense because
radiation [hardly/easily] penetrates it. The lung is deemed 
radiolucent because radiation [hardly/easily] penetrates it.
(Absorption = 1/penetration.)
27
Scattered radiation [increases/decreases] contrast, degrading the
image. A grid (G) is a large thin plate composed of thin parallel
strips of metal and wood. As shown in Figure 1-11, the wood
strips permit most of the [direct/scattered] x-rays to reach the
film, while the metal strips absorb many of the [direct/scattered]
photons. [Figure 1-12A/Figure 1-12B] was taken witha grid. 
How did you decide?
25
scattered (deflected); 
direct (penetrating);
scattered (S)
26
more
less
hardly
easily
27
decreases
direct
scattered; 
Figure 1-12A
sharper, less noisy
A few technical points: What causes the blacks, whites, and grays of an x-ray
image? The x-ray beam contains x-ray photons of differing energies. As the x-ray
photons pass through the patient, some are absorbed completely (A), some 
penetrate directly to the x-ray film (P), and some are deflected (scattered) (SS).
Some of the scattered photons continue toward the x-ray film (S) (Figure 1-10).
Absorption and penetration are the reciprocal of each other. The differential
absorption of radiation by different tissues or diseases is responsible for all
radiographic images. Air, fat, soft tissue (muscle, fluid), and metal (bone)
absorb progressively more radiation. The thicker the tissue, the more it absorbs.
FIGURE 1-12 A FIGURE 1-12 B
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20 Felson’s Principles of Chest Roentgenology
FIGURE 1-13
FIGURE 1-14
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One • The Radiographic Examination 21
REVIEW
I
For the sharpest, truest images, the patient should be as [close
to/far from] the cassette as possible. The x-ray tube should be
[4 feet/5 feet/6 feet] from the cassette. The effects of scattered
radiation are minimized with a _____________.
II
Which view or technique, other than the routine PA and lateral,
would give the most information in the following situations?
(a) free pleural fluid on the right: _______________
(b) suspected air trapping behind an endobronchial 
tumor: __________________
(c) suspected right pneumothorax in patient who can’t sit or
stand: ________________
(d) bullet fragment, possibly in heart: _____________
III
In Figure 1-13, match density with letter:
(A) Air density ________________
(B) Metallic density ___________
(C) Soft tissue on face _________
(D) Soft tissue—on edge _______
IV
A. In emphysema, excess ____________ is trapped in the lung.
The air [absorbs/transmits] most of the radiation. The x-ray
film appears excessively [dark/light] in the emphysematous
regions.
B. Fluid (effusion, blood, pus) is more radiodense. It absorbs
[less/more] radiation than a normal lung. The diseased area
appears [dark/light].
C. In Figure 1-14, match density with letter:
(a) Normal ___________________
(b) Emphysema _______________
(c) Soft tissue/fluid ____________
D. The heart and the fluid (c) are the same radiodensity. Why is
the heart “whiter”?
I
close to
6 feet
grid
II
(a) right lateral decubitus
(b) expiratory
(c) left lateral decubitus
(d) fluoroscopy
III
(A) A
(B) B
(C) C
(D) D
IV
A. air
transmits
dark
B.
more
light
C.
(a) A
(b) B
(c) C
Thicker, absorbs more
radiation
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22 Felson’s Principles of Chest Roentgenology
FIGURE 2-1 A
L
L
L
FIGURE 2-1 B
FIGURE 2-2
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23
TWO
CROSS-SECTIONAL
IMAGING TECHNIQUES
Three relatively recent imaging techniques, computed tomography (CT), ultrasound (US),
and magnetic resonance imaging (MRI), have greatly improved thoracic imaging. In all 
conventional x-ray techniques, the x-ray beam passes through the patient, superimposing
all structures in its path onto an x-ray film or detector (projection image). Cross-sectional
scanning techniques “slice” the patient open, providing a look “inside,” eliminating 
superimposition. These images are the product of multiple digital readings, from multiple
angles, synthesized into a digital image. The digital data can be processed to improve tissue
contrast and brightness or to view the anatomy in various planes.
1
All cross-sectional imaging can be viewed in the “axial, sagittal,
coronal, or oblique planes.”
(a) An image perpendicular to the patient’s long axis is a(n)
_____________ image.
(b) An image parallel to the patient’s lateral plane is a(n)
____________ image.
(c) An image parallel to the patient’s frontal plane is 
a(n) ______________ image.
(d) All other images are _______________ images.
1
(a) axial
(b) sagittal
(c) coronal
(d) oblique
Figure 2-1A shows the axial (A), sagittal (B), and coronal planes (C). Figure 2-1B
shows the relationship of the sagittal, coronal, and oblique planes to the axial
plane. Axial images are viewed as if you were looking up from below. The patient’s
left is on your right.
CT provides the most useful cross-sectional imaging of the chest. The patient is
supine on a mobile table that passes through a cylindrical tunnel or gantry. In the
gantry wall, an x-ray tube (T) revolves around the patient (Figure 2-2). The x-ray
beam hits multiple small radiation detectors in the opposite gantry wall. Radiation
is detected, quantified, and synthesized into a digital image. (Don’t ask how—it’s
quite complicated.)
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24 Felson’s Principles of Chest Roentgenology
FIGURE 2-3 A
FIGURE 2-3 B FIGURE 2-3 C
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Two • Cross-Sectional Imaging Techniques 25
2
The CT scanner routinely produces [axial/coronal/sagittal] images
(Figure 2-3A). In Figure 2-3B, the same data set is reconstructed
in the ____________ plane of the trachea. In Figure 2-3C, it is
through the ___________ plane of the trachea. In Figures 2-3B
and 2-3C, arrows point to an area of _____________.
2
axial
coronal
sagittal; tracheal narrow-
ing or stenosis
The same digital data can be displayed in subsets to optimize the contrast for
each type of tissue. In the thorax, it is routine to look at images reconstructed to
show lung detail (“lung window”), mediastinal detail (“soft tissue or mediastinal
window”), and bone detail (“bone window”).
3
Figure 2-3A is a(n) [axial/sagittal/coronal] image reconstructed
to show [lung/mediastinal/bone] detail, whereas Figure 2-4 shows
[lung/mediastinal/bone] detail in the same patient. To achieve
this, the patient was scanned [twice/once].
3
axial
lung
mediastinal
once
FIGURE 2-4
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26 Felson’s Principles of Chest Roentgenology
FIGURE 2-5
c
FIGURE 2-6 A
FIGURE 2-6 B
FIGURE 2-6 C
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Two • Cross-Sectional Imaging Techniques 27
4
Radiography and CT use x-rays. By convention, the synthesized
CT image of the normal lung is black because the lung is 
radio __________. The bone is white because it is 
radio _____________. Muscle, water, and fat absorb progressively
less radiation and are progressively [lighter/darker] shades 
of gray.
5
Conventional radiographs are able to distinguish four basic
tissue densities. In order of increasing x-ray absorption, they are:
(a) air (c) ________________
(b) _________________ (d) ________________
4
lucent (transmits)
dense (absorbs)
darker
5
(b) fat
(c) soft tissue (water)
(d) bone (metal)
CT has better contrast discrimination than conventional x-rays and more easily
distinguishes between muscle, fluid (e.g., blood, bile), and fat. CT density is
expressed in Hounsfield units (HU). The scanner is calibrated so that pure water =
0 HU. Typical HU values are: lung = − 800, fat = − 80-120, fluid = 0, muscle = + 40,
and bone = >+ 350. Figure 2-5 shows the various CT densities in HUs.
6
Although [x-ray/CT] has better contrast discrimination, the heart,
the vessels, the mediastinal structures, and the muscles are
similar intermediate shades of gray. This soft tissue density is
approximately [− 40/0/+ 40] HU. Iodinated contrast medium is
often given intravenously during the scan to increase the 
radiodensity of blood. The heart and vessels absorb [more/less]
radiation than surrounding structures and appear [white/black].
6
CT
(+) 40
more
white
Figure 2-6A is an axial CT scan emphasizing the soft tissue or mediastinal structures
(“mediastinal or soft tissue windows”). In Figure 2-6B, intravenous contrast
medium was given during scanning. Note the change in the density of the aortic
arch (A) and the superior vena cava (S). Figure 2-6C is a left anterior oblique 
two-dimensionalreconstruction, from the same digital data. Note the radiodense
calcified (c) aortic plaque in Figures 2-6A and 2-6C.
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28 Felson’s Principles of Chest Roentgenology
FIGURE 2-7
FIGURE 2-8 A
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Two • Cross-Sectional Imaging Techniques 29
7
Axial images assume you are viewing the patient from
[above/below]. The patient’s right is on your left (as in the chest
x-ray). In Figure 2-7, the [right/left] lung is normal. The branching
structures that taper peripherally are the ______________. 
The radiolucent areas are the air-containing lung parenchyma.
The ______________ lung contains a tumor. It absorbs [more/less]
radiation than normal lungs. The tumor is radio ____________.
8
Computers that are more powerful create images that are more
powerful. They create three-dimensional images that can be
viewed from any direction. Figure 2-8A is a three-dimensional
view of the aorta. Compare with the two-dimensional recon-
struction of the same aorta (Figure 2-6C). The same data 
set used for Figure 2-3 provides a three-dimensional view of 
the ____________ in Figure 2-8B. This is virtual bronchoscopy.
7
below
left
pulmonary vessels
right; more
dense
8
trachea (carina)
Radiography and CT produce images based on the differential absorption of 
ionizing radiation by different substances. MRI uses an entirely different set 
of physical properties. To oversimplify, the patient is exposed in a gantry to a
high-intensity magnetic field, and radiofrequency pulses are applied. Images are
based on the absorption and emission of radiofrequency energy. Different kinds
of pulses create different kinds of images so that a substance that appears white
on one set of images may appear black on a different set of images. Multiple sets
of images are acquired with each study, and the combined information from all
of the different images helps characterize tissues. These different sorts of images
may be referred to as weighted images depending on which characteristics 
of tissue are brought out by each “pulse sequence.” Images may be described as
relatively T1-weighted or T2-weighted. It is not necessary to learn what T1 and 
T2 mean, but it may be helpful to know that simple fluid tends to be bright on 
T2-weighted images and dark on T1-weighted images. (Note: Cerebrospinal fluid
is bright on T2-weighted images.)
FIGURE 2-8 B
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30 Felson’s Principles of Chest Roentgenology
FIGURE 2-9 A
FIGURE 2-9 B
FIGURE 2-10 A
FIGURE 2-10 B
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Two • Cross-Sectional Imaging Techniques 31
9
The gray scale (blacks, whites, and grays) of MRI [does/does not]
correspond to the densities of x-ray images. One would have to
know which __________ was used to understand the gray scale.
Fluid tends to brighten on [T1/T2].
9
does not
imaging sequence
T2
Figure 2-9 shows two MRI sequences of the same patient, with a right middle
mediastinal mass. In the axial image, Figure 2-9A, the paratracheal mass is
intermediate signal (i.e., gray) (white arrow). In the coronal image, Figure 2-9B,
the paratracheal mass is high signal (i.e., white) (white arrow). Note the low
signal (i.e., dark gray) in the lung and trachea and low signal in the spinal fluid
(black arrow).
MRI has the advantage of avoiding ionizing radiation and iodinated contrast
material. The gadolinium-based contrast materials used in MRI also are much
less likely to cause adverse reactions. MRI is contraindicated, however, for
patients with pacemakers, defibrillators, and a wide variety of implanted metal-
lic clips or devices. Each MRI sequence is relatively time-consuming, and multi-
ple sequences are necessary for each examination. Patients often experience
claustrophobia in the tubelike MRI gantry. MRI tends to be better able to answer
specific questions than to provide a broad survey of anatomy because of the
wide variety of available pulse sequences. It is generally less valuable for imag-
ing the lung than CT because the air within the lung provides relatively little MRI
signal. MRI is best used for imaging of the heart and vascular structures and to
answer a wide variety of neurologic, musculoskeletal, and abdominal imaging
questions.
10
In Figures 2-10A and 2-10B, MRI scans were acquired through
the left ventricle during the cardiac cycle. Left ventricular 
systole is depicted in [Figure 2-10A/Figure 2-10B]. How did 
you decide? _______________
10
Figure 2-10A
The left ventricular wall
is thicker; the chamber is
smaller
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32 Felson’s Principles of Chest Roentgenology
FIGURE 2-11 A
FIGURE 2-11 B
FIGURE 2-12
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Two • Cross-Sectional Imaging Techniques 33
11
US is particularly valuable for evaluating [pneumothorax/
empyema]. A simple pleural effusion (transudate) shows a low
and [heterogeneous/homogeneous] signal. Figures 2-11A and 2-11B
are US of the pleural space. The diaphragm (arrow) separates the
liver (L) from the pleural space. Note the signal difference between
the transudate (T) and an empyema (E).
11
empyema
homogeneous
In ultrasound (US) or sonography, a transducer directs high-frequency sound waves
into the body, much the way the Navy uses sonar. The sound waves reflect differ-
ently off different tissues. The transducer detects reflected sound waves and 
synthesizes them into diagnostic images. Fluid causes minimal reflection, so it
appears as a homogeneous low-signal area (low echogenicity). Soft tissue absorbs,
reflects, and deflects the signal, causing a heterogeneous echogenic area. Sound
waves travel poorly in air and bone. Bone-soft tissue and air-soft tissue interfaces
are hyperreflective. Air-filled lung and bone are difficult to evaluate with US. 
US is relatively inexpensive, portable, and especially suited for imaging pleural 
or pericardial fluid and cardiovascular structures in real time.
MRI and US are capable of rapid repetitive image acquisition. This permits 
evaluation of dynamic physiologic processes such as cardiac motion and blood
flow. Figure 2-12, an echocardiogram (US), shows the four cardiac chambers.
(LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle.)
12
Match the clinical problem with the best imaging modality:
A. pleural effusion ____________________ MRI
B. emphysema ________________________ US
C. cardiac function ____________________ neither
D. tumor invading mediastinum ________ either
12
A. US
B. neither
C. either
D. MRI
Now that you are in medicine, it is certain that at some family gathering, Aunt
Rose will ask you, “Exactly how safe is x-ray?” As with most important things,
there are no simple answers. Diagnostic levels of radiation are generally considered
safe for the individual, with the potential diagnostic benefits outweighing the barely
measurable, but real, population risks associated with diagnostic levels of 
ionizing radiation. The major risks are genetic damage and potential cancer
induction. Conventional chest radiographs produce very, very low radiation
exposure, whereas studies such as CT, fluoroscopy, and angiography give 
considerably higher doses. Radiation dose is cumulative over a lifetime (unlike
an old love affair, it doesn’t “wear off” with time). Patient radiation dose should
be kept to a minimum. This is especially true during the reproductive years,
during pregnancy, and during childhood because rapidly dividing cells are more
sensitive to radiation damage. The best way to reduce patient exposure is to
choose the correct imaging examination. If you are unsure, discuss it with the
radiologist.
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34 Felson’s Principles of Chest Roentgenology
FIGURE 2-13
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Two • Cross-Sectional Imaging Techniques 35
REVIEW
I
Conventional radiographs distinguish four basic tissue 
densities: __________, ________, ____________, and ___________.
[CT scans/radiographs] have bettercontrast discrimination.
II
US of a pericardial effusion (transudate) would be expected 
to be [homogeneous/heterogeneous] and have [low/high]
echogenicity, whereas a loculated pericardial infection would be
[homogeneous/heterogeneous] and of [low/high] echogenicity.
III
The CT scan in Figure 2-13 shows multiple intrathoracic densities.
Match the areas with their approximate Hounsfield units:
A. normal left lung _________ + 350 HU
B. pneumothorax __________ + 40 HU
C. lung mass ______________ 0 HU
D. calcified diaphragm _____ − 800 HU
E. pleural effusion _________ − 1000 HU
F. dome of diaphragm _____
G. vertebra _______________
IV
Who was Godfrey Hounsfield? ____________.
V
Diagnostic radiation should be held to a minimum in (check one
or more):
(a) children
(b) cancer patients
(c) pregnant women
(d) lawyers
I
air; fat; tissue (water);
metal (bone)
CT scans
II
homogeneous; low;
heterogeneous; high
III
A. − 800 HU
B. − 1000 HU
C. + 40 HU
D. + 350 HU
E. 0 HU
F. + 40 HU
G. + 350 or more
IV
He won the 1979 Nobel
Prize for Physiology or
Medicine for develop-
ing CT, shared with
Allan M. McCormack.
V
all, even lawyers
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36 Felson’s Principles of Chest Roentgenology
FIGURE 3-1 A
FIGURE 3-1 B
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37
THREE
THE NORMAL CHEST
X-RAY: READING
LIKE THE PROS
The keys to reading x-rays well are a good understanding of normal anatomy and an orderly
search pattern. This chapter reacquaints you with the normal anatomy and helps you
develop a search pattern that you can apply to every radiograph. By being systematic, you
will miss fewer important findings—not that experienced hands don’t miss findings; they
just miss fewer findings. Learn this ordered approach and then stick to it case after case.
You will look like a pro.
1
If you cannot tell a patient’s left from right, you will look like a
[pro/turkey]. A PA or an AP x-ray is always viewed as if you are
facing the patient from the [front/back].
2
You already know most of the anatomy; you just haven’t
thought about it in terms of a PA and a lateral projection. 
With projection images, all anatomic structures in the x-ray
beam are ____________. Mentally, you must fuse two projection
images (PA and lateral) into a three-dimensional understanding
of the anatomy.
3
Test yourself on Figures 3-1A and 3-1B. Study these diagrams
until you could give these answers in your sleep (perhaps you
are already doing that).
Posterior/anterior
A. ___________ D. ___________ G. ___________
B. ___________ E. ___________ H. ___________
C. ___________ F. ___________ J. ___________
Lateral
A. ___________ D. ___________ G. ___________
B. ___________ E. ___________ H. ___________
C. ___________ F. ___________ J. ___________
1
; front
2
superimposed
3
A. costophrenic sulcus
(angle)
B. left diaphragm
C. heart
D. aortic knob (arch)
E. trachea
F. hilum
G. carina
H. stomach bubble
J. ascending aorta
�Now turn the page, and redo with real films.
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38 Felson’s Principles of Chest Roentgenology
FIGURE 3-2 A
FIGURE 3-2 B
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Three • The Normal Chest X-Ray: Reading Like the Pros 39
4
Label radiographs in Figures 3-2A and 3-2B.
PA radiograph
A. __________ E. ___________
B. __________ F. ___________
C. __________ G. ___________
D. __________ H. ___________
Lateral radiograph
B. __________ H. ___________
C. __________ J. ___________
D. __________ K. ___________
E. __________
4
A. gas in splenic flexure
B. costophrenic sulcus
(angle)
C. heart
D. descending aorta
E. trachea
F. carina
G. hilum
H. aortic knob
J. ascending aorta
K. right diaphragm
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40 Felson’s Principles of Chest Roentgenology
FIGURE 3-3 A
FIGURE 3-3 B
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Three • The Normal Chest X-Ray: Reading Like the Pros 41
7
Arrange the following in viewing sequence:
A. mediastinum ________ D. lungs—bilateral ______
B. lung—unilateral ________ E. thorax ______
C. abdomen ________
Memory jog: Are There Many Lung Lesions?
7
Correct sequence:
A. 1—Abdomen
B. 2—Thorax (soft
tissues and bones)
C. 3—Mediastinum
D. 4—Lung—unilateral
E. 5—Lungs—bilateral
To maximize your accuracy, you must have an organized search pattern. Start
reading every radiograph—chest or otherwise—by scanning the areas of least
interest first, working toward the more important areas. You are less likely to
miss secondary but important findings this way. For the chest x-ray, start in the
upper abdomen, then look at the thoracic cage (soft tissues and bones), then the
mediastinal structures, and finally the lung. Look at each lung individually, then
compare left lung and right lung.
Abdomen: In Figure 3-3A, start in the right upper quadrant (*) and scan across
the upper abdomen several times. Normal gas-containing structures are the
stomach and the hepatic and splenic flexures of the colon. The liver is always
visible, and the spleen is often visible.
8
Scan the abdomen in Figure 3-3B.
A. The gas collection just below the heart = ___________.
B. The gas collection lateral to A = ____________.
C. The homogeneous density below the right diaphragm 
= ______________.
D. The right diaphragm is higher. This is [normal/abnormal].
8
A. stomach bubble
B. splenic flexure of
colon
C. liver
D. normal
Clinical Pearl: Upper abdominal disease (subphrenic abscess, perforated viscus,
pancreatitis, and cholecystitis) may mimic lung disease clinically. Similarly,
basilar lung disease (pneumonia, pleurisy) may mimic upper abdominal disease.
This is real!
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42 Felson’s Principles of Chest Roentgenology
FIGURE 3-4 A
FIGURE 3-4 B
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Three • The Normal Chest X-Ray: Reading Like the Pros 43
9
In Figure 3-4B, identify the following structures:
A. ____________
B. ____________
C. ____________
D. ____________
E. ____________
F. ____________
G. ____________
9
A. right breast
B. posterior rib
C. scapula
D. clavicle
E. anterior rib
F. stomach bubble
G. liver
Thorax: In Figure 3-4A, start at the right base (*), looking at the soft tissues 
(e.g., muscles, breast) of the chest wall, the ribs, and the shoulder girdle in
sequence. Finish by reversing the order down the left side. These structures are
represented in Figure 3-4B. Note that the posterior ribs tend to be horizontal,
while the anterior ribs descend from lateral to medial.
Tombstone of the Village Hypochondriac
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44 Felson’s Principles of Chest Roentgenology
FIGURE 3-5 A
FIGURE 3-5 B
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Three • The Normal Chest X-Ray: Reading Like the Pros 45
10
On Figure 3-5C, identify the following structures in the order of
your mediastinal search:
1. _____________
2. _____________
3. _____________
4. _____________
5. _____________
6. _____________
7. _____________
10
1. trachea
2. carina
3. aortic knob (arch)
4. ascending aorta
5. descending aorta
6. heart
7. right hilum
Mediastinum: An organized search of the mediastinum is complicated because
there are multiple overlapping structures. Start with a global look at the 
mediastinum for contour abnormalities (i.e., focal or diffuse widening). 
Figures 3-5A and 3-5B show three rapid searches of the mediastinum: A = for the
trachea and carina; B = for the aorta and heart; C = for the hilum.
Note that the left hilum is normally slightly higher than the right.
FIGURE 3-5 C
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46 Felson’s Principles of Chest Roentgenology
FIGURE 3-6 A
FIGURE 3-6 B
FIGURE 3-7 A
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Three • The Normal Chest X-Ray: Reading Like the Pros 47
11
See anything abnormal in Figure 3-7A? The abnormality is subtle.
Compare side to side. The change should be obvious (it is to me
anyway). There is a nodule in the _____________.
11
right midlung laterally,
over fourth anterior rib
(Who said this would be
easy?)
Lungs: Most chest x-rays areordered to evaluate lung disease, so the lungs are
examined last. The lungs are so important that we search them twice. Start in
the right costophrenic angle (*) as outlined in Figure 3-6A, examining the right
and then left lung. The second look involves a side-by-side comparison of the
lungs (Figure 3-6B). This also should give you a second look at costophrenic
angles and the hilum. Practice this search pattern in Figure 3-7A. Are There
Many Lung Lesions?
Clinical Pearl: The old x-ray is your best friend. Radiologists always look at old
films when available. You should, too. They help you detect new disease and
evaluate for change in preexisting disease. In Figure 3-7B, obtained 1 year earlier
than the x-ray in Figure 3-7A, the nodule was barely visible (arrows).
How do you tell who looked at the images last? A radiologist: The PAs and laterals
are in chronologic order. An internist: The PAs are in chronologic order, and the
laterals are in random order. A surgeon: All are in random order. An orthopedist:
Half are missing.
FIGURE 3-7 B
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48 Felson’s Principles of Chest Roentgenology
FIGURE 3-8 A FIGURE 3-8 B
FIGURE 3-9
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Three • The Normal Chest X-Ray: Reading Like the Pros 49
12
For the novice, subtle, and not so subtle, abnormalities are 
easy to miss. In searching the lungs, three helpful strategies 
to minimize oversights are (1) searching the lungs individually,
(2) searching the lungs ______________, and (3) taking advantage
of ______________, if available.
12
side-by-side
old radiographs
The lateral is a valuable but often ignored radiograph. Don’t ignore it! The
search pattern is identical (ATMLL). In Figure 3-8A, start by searching below the
diaphragm (A). Continue at the lower spine (B), searching the soft tissues and
bones posteriorly, then anteriorly (C). Return to the trachea and work your way
down the mediastinum (D). In Figure 3-8B, crisscross the superimposed lungs
and costophrenic angles (E).
13
Repeat the search in Figure 3-9. This patient is complaining 
of [dyspnea/cough/back pain] because of a ________________.
[Actually, you would need a frontal image to know it was inside,
not alongside the chest. This was inside.]
13
back pain; knife in back
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50 Felson’s Principles of Chest Roentgenology
FIGURE 3-10
FIGURE 3-11 A
FIGURE 3-11 B
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Three • The Normal Chest X-Ray: Reading Like the Pros 51
14
A bit of terminology about the lung parenchyma before we 
proceed. You have probably heard the terms “alveolar” and
“interstitial lung disease.” This terminology causes the most
confusion among nonradiologists and dyspepsia among semantic
purists. In the simplest terms, the lung parenchyma consists 
of air sacs and supporting structures. These air sacs are 
called ______________, they contain air, and they are [radiolucent/
radiodense] on x-ray. Figure 3-10 shows alveoli arranged into
acini around terminal airways. Several acini form a secondary
pulmonary lobule, the basic unit of lung function and gross
morphology.
15
Supporting the alveoli are vessels, lymphatics, bronchi, and
connective tissue. This support framework is known collectively
as the ______________ of the lung. On a normal chest x-ray, the
branching pulmonary arteries and veins are our only look at 
the interstitium. They appear white. They branch and taper and
become invisible in the outer third of the lung—not because
they don’t exist, but because they are _________________.
16
If a disease affects only the interstitium, the interstitial tissue
around the small vessels or interlobular septa [thickens/thins],
and they become [more visible/less visible] at the periphery 
of the lung. Because the air in the alveoli is hardly affected, 
the lung still appears well aerated.
14
alveoli; radiolucent
(black) (invisible)
15
interstitium
beyond the resolution
of the x-ray or CT (“too
tiny” for you nonscience
majors)
16
thickens
more visible
Figure 3-11A shows thickened interstitium and normal aeration. Compare with
normal interstitium in Figure 3-10.
17
If fluid or tissue (e.g., blood, edema, mucus, tumor) fills the air
sacs, the lungs become [radiodense/radiolucent]. The interstitial
markings are [more/less] visible within the alveolar consolidation.
The lungs appear homogeneously white. They are not aerated.
Figure 3-11B shows alveolar or airspace consolidation, whereas
Figure 3-11A shows _________________.
17
radiodense
less
interstitial thickening
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52 Felson’s Principles of Chest Roentgenology
FIGURE 3-12 A
FIGURE 3-12 B
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Three • The Normal Chest X-Ray: Reading Like the Pros 53
18
Let’s build on Figure 3-11. In Figure 3-11A, the alveoli are aerated
(black) and the interstitium is more prominent (white). The 
corresponding x-ray example of interstitial lung disease would
be [Figure 3-12A/Figure 3-12B]. Why? ___________. Figure 3-11B
and Figure 3-12B are a match. Both show _____________.
18
Figure 3-12A
Prominent markings,
aerated lungs
Airless lung obscuring
normal anatomy in the
lung apex (alveolar con-
solidation)
That’s it, alveolar and interstitial disease—grossly oversimplified—but a good place
to start. Try to analyze each abnormal x-ray with these patterns in mind.
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54 Felson’s Principles of Chest Roentgenology
FIGURE 3-13
FIGURE 3-14
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Three • The Normal Chest X-Ray: Reading Like the Pros 55
REVIEW
I
Chest x-ray reading sequence:
A = ______________
T = ______________
M = ______________
L = ______________
L = ______________
(Are There Many Lung Lesions?)
II
With the interstitial pattern, the lungs appear well [aerated/
consolidated], but the lung markings are __________________.
Conversely, with the alveolar pattern, the individual lung 
markings are _________________ because the surrounding lung
is ________________.
III
Search Figure 3-13 systematically. Then answer the following
questions below.
A. Which lung is more radiolucent? ________________
B. What is the cause of the density difference? __________
(Hint: Is this a male or female?)
IV
This patient has chest pain and some difficulty breathing. Search
Figure 3-14 systematically. Then answer the following questions.
A. The lungs are ______________.
B. The only radiographic finding is ______________.
C. The patient’s pain is due to _____________.
(If you got these answers, great, you searched systematically. 
If not, review questions 7-12.)
I
Abdomen
Thorax
Mediastinum
Lung—unilateral
Lungs—bilateral
II
aerated; thick (more
prominent); invisible
(hidden); airless (consol-
idated) (radiodense)
III
A. right (blacker, less
radiation absorption)
B. right mastectomy;
there is less x-ray
absorption and more
film blackening on
the right
IV
A. normal
B. free air under
diaphragms
C. perforated stomach
or bowel
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56 Felson’s Principles of Chest Roentgenology
FIGURE 4-1 A
FIGURE 4-1 B
FIGURE 4-1 C
FIGURE 4-1 D FIGURE 4-1 E
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57
FOUR
CHEST CT: PUTTING
IT TOGETHER
A chest x-ray is a two-dimensional summation image. We spend time synthesizing the 
superimposed anatomy on the PA and lateral into a three-dimensional understanding. CT is
the opposite task. The anatomy is not superimposed. We have to integrate the axial images
mentally to get the overall picture. Your knowledge of the radiographic anatomy will help
you understand CT scans. Conversely, CT anatomy will help you better understand 
radiographic anatomy. First, we need to master the CT anatomy and then develop ways 
to integrate the information.
Every CT scan starts with a scout view, a projection image that looks like a second-rate x-ray.
As you scroll through the axial images on a monitor, a line on the scout view tells you the
level you are at. Figure 4-1A shows that theaxial images (Figures 4-1B through 4-1E) were
done at the level of the aortic arch.
1
(a) The lungs are best seen on Figure 4-1 ____________.
(b) The mediastinum is best seen on Figures 4-1 ___________ 
and 4-1 ___________.
(c) The bones are best seen on Figure 4-1 _____________.
2
Figures 4-1B and 4-1E are mediastinal windows. Intravenous
contrast medium was administered in [Figure 4-1B/Figure 4-1E].
How did you know? __________________.
3
Let’s start by analyzing the mediastinum. It is easier to under-
stand the anatomy [with intravenous contrast medium/without
intravenous contrast medium]. So, we will learn with intravenous
contrast.
1
(a) C
(b) B and E
(c) D
2
Figure 4-1E
The vessels are whiter.
(That is, they absorb
more radiation after
intravenous contrast
injection.)
3
with intravenous con-
trast medium
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58 Felson’s Principles of Chest Roentgenology
FIGURE 4-2 A
FIGURE 4-2 B
FIGURE 4-2 C
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Four • Chest CT: Putting it Together 59
4
Figure 4-2A is called a(n) _________________. The three lines
indicate the scan locations of Figures 4-2B, 4-2C, and 4-2D.
Identify the following:
(a) ________________________
(b) ________________________
(c) ________________________
(d) ________________________
(e) ________________________
(f) ________________________
(g) ________________________
(h) ________________________
(i) ________________________
(j) ________________________
(*) ________________________
5
The thymus is a soft tissue triangle in front of the ascending aorta.
Like everything else after 40, it turns to _____________.
4
Scout view
(a) superior vena cava
(b) aortic arch
(c) thymus
(d) trachea
(e) ascending aorta
(f) descending aorta
(g) main pulmonary
artery
(h) right pulmonary
artery
(i) left ventricle
(j) right ventricle
(*) esophagus
5
fat
The pleura and pericardium also are seen on the mediastinal windows in 
Figure 4-2D. The pleura is seen as a very thin white line lining the thoracic cavity
(posterior arrow). The pericardium sits between two layers of fat as it encircles
the heart (anterior arrow). Normally, there is no visible fluid in the pleural
space, but there may be some fluid in the pericardial space.
Encyclopedia Britannica—unused. Have two teenagers who know
everything.
FIGURE 4-2 D
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60 Felson’s Principles of Chest Roentgenology
FIGURE 4-3 A
FIGURE 4-3 B
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Four • Chest CT: Putting it Together 61
6
Figure 4-3A shows [lung/mediastinal/bone] windows. The
anatomy is easy. The linear white branching structures are 
the _________. The black tubular structures with white borders
are the ___________. In the periphery, they [enlarge/disappear].
Small vessels and bronchi are beyond the resolution of the 
CT image.
7
When a CT image is perpendicular to a vessel or bronchus, 
it appears as a [circle/line].
8
The area between the vessels is the lung parenchyma. The lung
is mostly [soft tissue/water/air]. It is [radiodense/radiolucent]
and appears [black/white].
9
In Figure 4-3B, identify at lung windows:
(A) ______________________
(B) ______________________
(C) ______________________
(D) ______________________
(E) ______________________
10
In Figure 4-3B, the thin white lines (D) are the major fissures.
They are formed by the [visceral/parietal] pleura covering 
the individual lobes.
6
lung
arteries and veins
bronchi; disappear
7
circle
8
air; radiolucent (absorbs
little radiation)
black
9
(A) left pulmonary artery
(B) pulmonary artery or
vein
(C) right main stem
bronchus
(D) major fissures
(E) normal parenchyma
10
visceral
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62 Felson’s Principles of Chest Roentgenology
FIGURE 4-4 A
FIGURE 4-4 B
FIGURE 4-5
FIGURE 4-6
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Four • Chest CT: Putting it Together 63
11
Figures 4-4A and 4-4B are through the same anatomy. [Figure 4-4A/
Figure 4-4B] is a high-resolution image. To achieve the high 
resolution, the image is [1.25 mm/2.5 mm/5 mm] thick recon-
structed with an algorithm that [blurs/sharpens] edges. Note the
difference in detail.
12
Pop Quiz: Tissue Density on CT
A. Lung = [−800/−500/+500/+800] HU
B. Fluid = [−200/0/+50/+2000] HU
C. Liver = [−400/−40/+40/+400] HU
D. Bone = [−350/−35/+35/+350] HU
13
To look at the bones, we use _______________ windows.
14
The ribs are difficult to follow because they run obliquely
through the axial images. Other bones are easier to follow. On
Figure 4-5, identify at bone windows:
(A) ___________________
(B) ___________________
(C) ___________________
(D) ___________________
(E) ___________________
15
The upper abdomen is visible at mediastinal windows on the
images through the lung bases and the diaphragms (Figure 4-6).
It is an unrequested bonus, but is often helpful.
(A) ___________________
(B) ___________________
(C) ___________________
(D) ___________________
(E) ___________________
(F) ___________________
11
Figure 4-4A
1.25 mm
sharpens
12
A = −800
B = 0
C = +40
D = +350
13
bone
If you missed this, you
may want to return the
book for a refund.
14
(A) rib
(B) sternum
(C) scapula
(D) vertebral body
(E) spinal canal
15
(A) stomach
(B) liver
(C) spleen
(D) splenic flexure
(E) diaphragm
(F) left lower lobe (lung)
High-resolution CT: To maximize lung detail for evaluating fine interstitial lung
disease, we use two strategies: We take thinner sections (1.25 mm instead of 
2.5 or 5 mm), so there is less overlap with adjacent tissue (i.e., volumes averaging),
and we use CT image reconstruction algorithms that sharpen edges.
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64 Felson’s Principles of Chest Roentgenology
FIGURE 4-7
FIGURE 4-8 A
FIGURE 4-8 B
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Four • Chest CT: Putting it Together 65
16
The best of both worlds: With high-end CT equipment, the 
axial images are very thin (0.5-2 mm thick versus 5-10 mm thick).
High quality axial images can be reconstructed in any plane
desired, giving us alternative looks at the intrathoracic
anatomy. Review Figure 4-7. Plane A is the [axial/sagittal/coronal]
plane. Plane B is the [axial/sagittal/coronal] plane. Plane C is the
[axial/sagittal/ coronal] plane.
17
Figure 4-8A is a [lung/mediastinal/bone] window in the
[axial/coronal/sagittal] plane. It is lateral to the heart and great
vessels.
18
Figure 4-8B is a [lung/mediastinal/bone] window. It is
[axial/coronal/sagittal]. It is thought to be [the carina/the lung
only/both ventricles].
16
axial
sagittal
coronal
17
lung
sagittal (parasagittal)
18
lung
coronal
the carina
For Sale: Tombstone—great deal for anyone named K. P. Brzywanoski III.
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66 Felson’s Principles of Chest Roentgenology
FIGURE 4-9 A
FIGURE 4-9 B
FIGURE 4-10 A
FIGURE 4-10 B
FIGURE 4-10 C FIGURE 4-10 D
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Four • Chest CT: Putting it Together 67
19
We finished Chapter 3 by discussing the plain film appearance
of alveolar and ___________ patterns of disease. Figure 4-9A is a
diagram of air in the alveoli (black) and the normal interstitium
(white), which compares with a normal high-resolution CT scan
(Figure 4-9B).
20
With alveolar consolidation, the lung is [airless/well aerated].
The lung is [white/black]. It is said to be [radiodense/radiolucent].
21
With interstitial disease, lung aeration is [almost normal/markedly
diminished/absent]. The interstitial markings (pulmonary 
vessels, bronchi, and connective tissue) are [more/less] promi-
nent than normal.
22
Figure 4-10A represents alveolar consolidation, and Figure 4-10B
represents an interstitial pattern. Figure 4-10C represents 
an [alveolar/interstitial] pattern. Figure 4-10D represents an
[alveolar/interstitial] pattern. Figure 4-10E represents an 
[alveolar/interstitial] pattern.
19
interstitial
20
airless
white; radiodense
(absorbs radiation)
21
almost normal
more
22
interstitial
alveolar
interstitial
FIGURE 4-10 E
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68 Felson’s Principles of Chest Roentgenology
FIGURE 4-11 A
FIGURE 4-11 B
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Four • Chest CT: Putting it Together 69
REVIEW
I
For Figures 4-11A, 4-11B, and 4-11C:
A. Sagittal = _________________.
B. Coronal = _________________.
C. Axial = ____________________.
II
For Figures 4-11A, 4-11B, and 4-11C:
A. Lung window = __________________.
B. Mediastinal window = ____________.
C. Bone window = __________________.
III
For Figures 4-11A, 4-11B, and 4-11C:
A. There is a focal density in the ______________ lobe.
B. It is an example of [alveolar/interstitial] consolidation.
IV
What might this represent in a:
A. 20-year-old man? _________________
B. 68-year-old man? _________________
I
A. Figure 4-11B
B. Figure 4-11C
C. Figure 4-11A
II
A. Figure 4-11C
B. Figures 4-11A and 
4-11B
C. none
III
A. right upper
B. alveolar
IV
A. focal pneumonia 
or inflammatory
process
B. lung cancer
FIGURE 4-11 C
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70 Felson’s Principles of Chest Roentgenology
FIGURE 5-1 AB
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71
FIVE
LOBAR ANATOMY
A “fingertip” knowledge of lobar and segmental anatomy is indispensable for understanding
patterns of lung collapse and patterns of lung disease. Some diseases have lobar or segmental
distributions; others do not. Understanding the lobar anatomy also is important for planning
bronchoscopy, surgery, radiation therapy, and postural drainage.
1
The inner thoracic wall is lined by the _______________ pleura,
while each lobe is surrounded by the _______________ pleura.
The space between the visceral pleura and parietal pleura is
cleverly named the _______________.
2
The space between the lobes, where the _______________ pleu-
ral surfaces touch, is called the interlobar fissure. Because the
visceral pleura is less than 1 mm thick, the x-ray beam must
strike it parallel to its surface if it is to be visible on the radio-
graph. If a fissure is [parallel/perpendicular/oblique] to the 
x-ray beam, it will not be visible.
3
In Figure 5-1A, the x-ray beam is [perpendicular/parallel] to the
fissure or septum. The fissure [will/will not] be visible on the
radiograph.
In Figure 5-1B, the x-ray beam is [perpendicular/parallel/
oblique] to the visceral pleural surfaces. The fissure [will/will
not] be visible on the radiograph.
1
parietal
visceral
pleural space
2
visceral
perpendicular
or oblique
3
parallel
will
oblique
will not
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72 Felson’s Principles of Chest Roentgenology
FIGURE 5-2 A
FIGURE 5-2 B
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Five • Lobar Anatomy 73
4
We challenge you to test your anatomic recall:
(a) Which lung is smaller? _______________.
(b) Name the lobes of the right lung. _______________,
_______________ and _______________.
(c) Name the lobes of the left lung. _______________ and
_______________.
5
Figure 5-2A shows that, in the left lung, the upper lobe (U ) is
separated from the lower lobe (L) by the _______________
(arrows). The major fissure (touched up for easy visibility) is
[perpendicular/parallel] to the x-ray beam only in the lateral
projection. Figure 5-2B is a parasagittal CT reconstruction
showing the left major fissure (arrows).
6
The oblique (major, vertical) fissure is not visible on the normal
frontal projection because (choose one):
(a) It is often anatomically absent.
(b) It is not parallel to the x-ray beam.
(c) It has the same roentgen density as lung tissue.
7
In the right lung, the major (oblique) fissure separates the right
upper and middle lobes from the _______________. On the left,
it separates the _______________ and _______________.
4
(a) left, because heart is
on left
(b) upper, middle, lower
(c) upper (lingula is part
of left upper lobe),
lower
5
major (oblique) (vertical)
fissure
parallel
6
(b) It is not parallel to
the x-ray beam.
7
right lower lobe
left upper; left lower
lobes
The major fissure runs obliquely downward from about the level of the fifth 
thoracic vertebra to the diaphragm, where it ends at a point just short of the
anterior chest wall (Figures 5-2A and 5-2B).
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74 Felson’s Principles of Chest Roentgenology
FIGURE 5-3 A FIGURE 5-3 B
FIGURE 5-4 A
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Five • Lobar Anatomy 75
8
The minor (horizontal) fissure separates the right middle lobe
from the [right upper/right lower] lobe. In an erect patient, the
minor fissure is usually horizontal. It is [parallel/perpendicular]
to the floor. This fissure should be visible in [the frontal/the 
lateral/both] view(s) (Figure 5-3B and Figures 5-4A and 5-4B).
9
In many patients, the minor fissure is not perfectly horizontal.
The anterior portion or the entire fissure slopes downward or
is bowed, making it visible in the _______________ projection
only. In others, the minor fissure is anatomically incomplete
and not visible in one or both views.
8
right upper
parallel
both
9
lateral
The fissure normally appears as a thin white line (2 layers of pleura surrounded
by air) as in Figure 5-3A (arrowheads). There are two exceptions. If a lobe is con-
solidated, the fissure appears as an edge, delineating that lobe. In Figure 5-3A,
the lower fissure is a line (arrowheads), but the upper fissure is an edge
(arrows) because the upper lobe is consolidated or airless. If pleural fluid
enters a fissure, the fissure thickens. Note the thick major fissure (arrowheads)
and normal minor fissure (arrow) in Figure 5-3B.
Just to confuse you a little, a small percentage of people have a left minor 
fissure between the lingula and the rest of the upper lobe. Watch for it.
FIGURE 5-4 B
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76 Felson’s Principles of Chest Roentgenology
FIGURE 5-5
FIGURE 5-6 A
FIGURE 5-6 B
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Five • Lobar Anatomy 77
10
On the lateral film (Figure 5-5), the minor fissure starts posteriorly
at the _______________ fissure and ends on the _______________
wall. This often helps you distinguish the right from the left
major fissure on the lateral view.
10
right major; anterior
chest
11
Identify the following fissures on Figures 5-6A and 5-6B:
(a) I = _______________.
(b) II = _______________.
(c) III = _______________.
12
Identify the following in Figures 5-6A and 5-6B:
(a) 1 and 2 = _______________.
(b) 3 and 5 = _______________.
(c) 3 and 4 = _______________.
(d) 5 = _______________.
(e) 6 = _______________.
(f) 7 = _______________.
11
(a) I = minor fissure
(b) II = right major 
fissure
(c) III = left major fissure
12
(a) 1 and 2 = upper lobes
(b) 3 and 5 = right lower
and middle lobes
(c) 3 and 4 = lower lobes
(d) 5 = right middle lobe
(e) 6 = lingula
(f) 7 = left diaphragm
In the lateral view, it still may be difficult to tell the two major fissures apart.
Here is a simple method: The left major fissure ends on the left diaphragm
(Figure 5-5) (arrow). The left diaphragm is usually lower, usually has the stomach
bubble immediately beneath it, and is not visible anteriorly because the bottom
of the heart rests on it.
Note: On the frontal view (Figure 5-6A), the superior portions of the lower lobes
rise to the level of the aortic arch (dotted lines). The upper portion of the lower
lobes (superior segment) is superior to the hilum.
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78 Felson’s Principles of Chest Roentgenology
FIGURE 5-7 A
FIGURE 5-7 B
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Five • Lobar Anatomy 79
13
In Figures 5-7A and 5-7B, there is [alveolar consolidation/inter-
stitial thickening] located in the _______________ lobe. The
major fissure (arrow) forms the [superior/posterior] right
middle lobe boundary. The superior margin of the right middle
lobe is the _______________ fissure (arrowhead).
13
alveolar consolidation
right middle
posterior
minor
Clinical Pearl: Lobar pneumonia is usually bacterial in origin, caused by
Streptococcus pneumoniae or Klebsiella. Mycoplasmaand Legionella infections
also may cause lobar consolidation.
On radiographs, fissures are seen when parallel to the x-ray beam. On CT, struc-
tures are best seen when perpendicular to the scan plane. The major fissures
(arrows) are usually visible on axial CT images (Figure 5-8). The minor fissure is
parallel to the scan plane and not visible.
FIGURE 5-8
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80 Felson’s Principles of Chest Roentgenology
FIGURE 5-9 A
FIGURE 5-9 B
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Five • Lobar Anatomy 81
14
What about other fissures? There are three accessory fissures
seen occasionally in normal individuals. The azygos fissure
(Figure 5-9A) is formed by an anomalous development of the
azygos vein. The vein “migrates through” the medial right
upper lobe, dragging visceral and parietal pleura with it. The
azygos lobe is separated from the rest of the upper lobe by the
azygos _______________ (arrow). Figure 5-9B shows a CT scan of
an azygos fissure and lobe.
15
The azygos fissure separates a variable amount of the upper
medial region of the _______________ lobe. This portion of the
lung is called the _______________ lobe. This information is of
[great/little] clinical importance but interesting nonetheless.
14
fissure
15
right upper
azygos
little
Four doctors are duck hunting. As the ducks fly over, the internist says, “It looks
like a duck, smells like a duck, and quacks like a duck. I just need a second opin-
ion.” By the time he is ready, the ducks are gone. The radiologist says, “It looks
like a duck, smells like a duck, and quacks like a duck. I need another view.” 
By the time he is ready, the ducks are gone. The surgeon just shoots and says,
“Holy mackerel, what did I just shoot?” The pathologist says, “I think they were
ducks, but I will need more tissue.”
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82 Felson’s Principles of Chest Roentgenology
FIGURE 5-10 A
FIGURE 5-10 B
FIGURE 5-11
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Five • Lobar Anatomy 83
16
Figure 5-10A shows the position of another accessory fissure
(arrows), the inferior accessory fissure. It separates the medial
basal segment of the _______________ lobe from the remainder
of the lobe. Figure 5-11 shows the inferior accessory fissure
(arrow).
17
The azygos and inferior accessory fissures run in an anterior-
posterior plane. They are visible in [the frontal/the lateral/both]
view(s).
18
The third accessory fissure is the superior accessory fissure. 
In Figures 5-10A and 5-10B, this fissure (arrowheads) is in the
same plane and posterior to the _______________ fissure. 
It should be visible in [the frontal/the lateral/both] view(s). 
A right superior accessory fissure superimposes on the minor
fissure in the _______________ view.
19
The superior accessory fissure divides the right _______________
lobe into two portions: the four basal segments and the [superior/
inferior/apical] segment.
16
right lower
17
the frontal
18
minor
both
frontal
19
lower
superior
Train yourself to look for the fissures on every chest image. They help to localize
disease in the lung. As we shall see, displacement of the fissures is the most reliable
sign of lobar collapse.
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84 Felson’s Principles of Chest Roentgenology
FIGURE 5-12 A
FIGURE 5-12 B
FIGURE 5-13 A
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Five • Lobar Anatomy 85
REVIEW
I
Identify the fissures in Figures 5-12A and 5-12B:
(1) _______________
(2) _______________ or _______________
(3) _______________
(4) _______________
(5) _______________
(6) _______________
(7) _______________
II
The only fissures visible on the frontal and lateral view are the
_______________ fissure and the _______________ fissure. Why?
_______________.
III
An unlucky seamstress gasped at the wrong moment. Carefully
scan Figures 5-13A and 5-13B, then answer the following 
questions:
A. What is the abnormality? _______________
B. In what lobe is it located? _______________
I
(1) azygos
(2) minor; superior
accessory
(3) inferior accessory
(4) right major
(5) minor
(6) superior accessory
(7) left major
II
minor; superior accessory
Parallel to beam in 
both projections (both
horizontal)
III
A. aspirated a pin
B. right lower lobe
FIGURE 5-13 B
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86 Felson’s Principles of Chest Roentgenology
FIGURE 6-1
FIGURE 6-2
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87
SIX
THE SILHOUETTE SIGN
If part of the lung is radiodense (alveolar pattern, consolidated, water density, airless), it
can affect our ability to see adjacent structures. We can use these changes to help us detect
and localize disease in the lung. This chapter discusses how disease in different lobes
affects the appearance of adjacent organs.
1
There are four basic radiographic densities. In order of 
increasing radiodensity, they are gas, _______________,
_______________, and _______________.
1
fat
soft tissue (water);
metal (bone)
2
water (soft tissue)
air
Figure 6-1 shows an upright test tube containing, from top down, air, oil (fat),
water, and metal. Calcium is the prime example of metal density normally found
in the body. Note the sharp interface between each density. (Arrow = air/fat
interface; arrowhead = fat/water interface.)
In Figure 6-2, the heart, aorta, and diaphragms have sharp margins because they
are all water density, adjacent to air density. The inner stomach wall is visible
because air contacts the soft tissue wall. Converseley, the liver and right
diaphragm are not seen separately because they are both of water density.
2
Anatomic structures are recognized on an x-ray by their den-
sity differences. These four basic densities keep the radiologist
in business. Figure 6-2 is a normal chest x-ray. The heart and 
muscles are _______________ density. The lung and stomach
bubble are _______________ density. The fat planes between
the muscles are barely visible. The “L” marker is metal (lead)
density and the ribs are metal density.
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88 Felson’s Principles of Chest Roentgenology
A B C
FIGURE 6-3
FIGURE 6-4
FIGURE 6-5
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Six • The Silhouette Sign 89
3
Let us reinforce this concept. Figure 6-3 shows three x-rays of a
model of the heart and aorta. In Figure 6-3A, the heart and
ascending aorta are in one empty box, and the descending
aorta is in a second empty box, behind the first. In Figure 6-3B,
some water has been poured into the anterior box. The lower
heart borders have disappeared. The descending aorta is [visi-
ble/not visible]. In Figure 6-3C, the water has been removed and
placed in the posterior box. The lower heart border is
[visible/not visible]. The lower aortic border is not visible
because _______________.
3
visible
visible
aorta now contacts
water, rather than air
4
air
soft tissue (water)
soft tissue
5
A, B, C
similar
In Figure 6-4, the left diaphragm is visible, but the right is not because the adjacent
right lower lobe is consolidated (airless)—the silhouette sign. The right heart
border, still in contact with aerated right middle lobe, is visible. The left heart
border is normal.
The heart, aorta, and blood—as well as the liver, spleen, and muscles—all are
soft tissue density. So is diseased airless lung. Two substances of the same den-
sity, in direct contact, cannot be differentiated from each other on an x-ray. This
phenomenon, the loss of the normal radiographic silhouette (contour), is called
the silhouette sign.
4
In Figure 6-4, the trachea, which is _______________ density,
can be differentiated from the mediastinum, which is
_______________ density. The liver and diaphragm cannot be
separated because both are _______________ density and in
direct contact.
5
In Figure 6-5, which structures are visible?
A. Right diaphragm
B. Right heart
C. Left diaphragm
D. Left heart
An interface is not visible when two areas of [similar/
different] radiodensity touch.
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90 Felson’sPrinciples of Chest Roentgenology
FIGURE 6-6 A
FIGURE 6-6 B
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Six • The Silhouette Sign 91
6
Now that you know what the silhouette sign is, what are you
going to do with it? The silhouette sign helps diagnose and
localize lung disease. If you know the position of intrathoracic
structures, you can precisely localize the lung disease. The
heart and ascending aorta are [anterior/posterior] structures.
Conversely, the descending aorta is a(n) [anterior/posterior]
structure. The aortic arch crosses the middle mediastinum from
_______________ on the right to _______________ on the left.
6
anterior
posterior
anterior; posterior
Figure 6-6A is a lateral view of the chest with an atherosclerotic (calcified) aortic
wall. The heart and ascending aorta (A) are anterior, and the descending aorta
(D) is posterior. Figure 6-6B is a CT scan taken through the aortic arch as it
passes from right anterior to left posterior. In Figure 6-6C, the ascending aorta 
(A) is anterior, and the descending aorta (D) is posterior. (P = pulmonary artery.)
FIGURE 6-6 C
7
The diaphragms contact the _______________ surface of the
lung. The _______________ lobes contact the diaphragm.
8
There is even a “normal” silhouette sign on the lateral chest 
x-ray. In Figure 6-6A, we see two diaphragms posteriorly, but
only one anteriorly. The heart sits on the [right/left] diaphragm,
obscuring the anterior diaphragm. How can this be useful?
_______________.
7
inferior
lower
8
left
It helps to distinguish the
left and right diaphragms
on the lateral
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92 Felson’s Principles of Chest Roentgenology
FIGURE 6-7
FIGURE 6-8 A
FIGURE 6-8 B
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Six • The Silhouette Sign 93
9
Let’s wrap this up. State the anterior or posterior location of
each of the following:
(a) right heart border = _______________
(b) descending aorta = ________________
(c) left heart border = _________________
(d) ascending aorta = _________________
(e) aortic knob (arch) = _______________
10
Each lobe produces a characteristic silhouette sign of which we
can take advantage. The right middle lobe and lingula lie in
anatomic contact with the _______________. All are [anterior/
posterior] structures. In the chest x-ray in Figure 6-7, the heart
border is not visible on the _______________. There must be
consolidation (water density) in the _______________ lobe.
9
(a) anterior
(b) posterior
(c) anterior
(d) anterior
(e) mid posterior
10
heart
anterior
right (silhouette sign)
right middle
11
visible
Diaphragms are adjacent
to aerated lower lobes
12
posterior; major
diaphragms
In Figure 6-8A, there is a silhouette sign of the left heart border. In Figure 6-8B,
the CT scan shows the consolidated lingula adjacent to the left heart.
11
In Figures 6-7 and 6-8A, the diaphragms are [visible/invisible].
Why? _______________.
12
Let’s look at the lower lobes. They sit inferior and
[anterior/posterior] to the [major/minor] fissure. They are not
in anatomic contact with the heart borders, which are anterior
structures. Instead, the lower lobes sit on the _______________,
which are inferior structures.
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94 Felson’s Principles of Chest Roentgenology
FIGURE 6-9
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Six • The Silhouette Sign 95
13
If only the right diaphragm is obscured, the disease is in the
_______________. If the right heart border and the diaphragm
are obscured, there is consolidation of the _______________ and
_______________.
14
Airspace disease in either lower lobe overlaps the hilum and
the heart border, but does not obscure their silhouette because
they are _______________.
15
The descending aorta is not visible when there is
_______________ consolidation, as in Figure 6-9. Compare with
Figures 6-7 and 6-8.
13
right lower lobe
right middle lobe
right lower lobe
14
not in direct contact
15
left lower lobe
Figure 6-9 shows bilateral disease. On the right, there is a silhouette sign of the
right heart and the diaphragm, indicating right middle and lower lobe disease.
The left diaphragm is not visible because of a left lower lobe consolidation. The
left heart border is sharp; the lingula is aerated.
Clinical Pearl: In the ICU, left lower lobe atelectasis or pneumonia is frequent.
Check the diaphragm and descending aorta through the heart on every film for
a silhouette sign.
Woman in labor: “Can’t. Shouldn’t. Didn’t. Won’t.”
Husband: “Doctor, what’s wrong with my wife?”
Obstetrician: “Contractions!”
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96 Felson’s Principles of Chest Roentgenology
FIGURE 6-10
FIGURE 6-11
FIGURE 6-12
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Six • The Silhouette Sign 97
16
The upper right heart border and [ascending/descending]
aorta are anterior structures on the right. The descending aorta
is _______________ on the left. The trachea and the aortic knob
are located in the [anterior/mid/posterior] thorax.
17
The right upper lobe occupies the anterior and midthorax
above the _______________ fissure and anterior to the
_______________ fissure. Right upper lobe consolidation causes
a silhouette sign of the [ascending/descending] aorta and the
right tracheal lung interface. Figure 6-10 shows right upper lobe
consolidation obscuring the upper mediastinum and ascending
aorta.
18
The left upper lobe occupies the anterior and mid upper thorax.
Left upper lobe consolidation (upper division) obliterates the
_______________ atrium, the aortic knob, and the _______________
and _______________ mediastinum. Figure 6-11 shows the 
silhouette sign in left upper lobe consolidation.
19
You have seen that a silhouette sign helps localize disease.
Sometimes it actually helps detect disease. Study Figure 6-12
carefully. There are two subtle silhouette signs indicating dis-
ease in the _______________ and _______________. Note: Both
heart borders are indistinct. You would need a lateral film or CT
scan to confirm.
16
ascending
posterior
mid
17
minor
major
ascending
18
left; anterior
middle
19
right middle lobe; lingula
A positive silhouette sign is very helpful. A negative silhouette sign does not
ensure that a given lobe is disease-free because it may be partially aerated and
not cause a silhouette sign. Be careful!
You have learned that the silhouette sign applies to radiodense lung lesions. 
It also applies to soft tissue density mediastinal and pleural lesions. It applies
whenever two structures of the same density are in contact.
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98 Felson’s Principles of Chest Roentgenology
FIGURE 6-13
FIGURE 6-14
FIGURE 6-15
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Six • The Silhouette Sign 99
20
Figure 6-13 shows a mediastinal mass obscuring the ascending
aorta and the tracheal-lung interface. This large mass must be
in the _______________ and _______________ mediastinum.
What does it do to the tracheal width? _______________.
21
We learned there is even a normal silhouette sign on the 
lateral radiograph that we can use to our advantage. The heart
sits predominantly on the [anterior/posterior] [left/right]
diaphragm. Both structures are of _______________density. The
[anterior/posterior] part of the left diaphragm is usually not 
visible. On the lateral, the right diaphragm is visible through
the heart because _______________. This helps distinguish the
left from the right diaphragm on the lateral.
20
anterior; middle
It narrows the tracheal
width
21
anterior; left
soft tissue (water)
anterior
it contacts aerated lung
Now that everything is clear—here come the exceptions. (1) The silhouette sign
may be misleading on an underpenetrated radiograph (a film that is too light).
Figure 6-14 is an underpenetrated film. The left diaphragm and descending aorta
are not visible through the heart. If you cannot see the spine through the heart, the
film is underpenetrated, and a silhouette sign may be misleading. (2) Sometimes
the right heart borderoverlies the spine and does not protrude into the right
lung. The density of the spine hides the lung-heart interface. You can’t hit ’em if
you can’t see ’em.
Figure 6-15 shows two silhouette signs of the left diaphragm. The anterior one is
due to the heart, and the posterior one is due to pneumonia (P) in the left lower
lobe. Only the middle third of the left diaphragm is visible (*). The entire right
diaphragm is visible.
The silhouette sign is nearly always an abnormal finding. It is usually due to
lung disease. It may be present even when you cannot see the disease causing it.
On every chest film you see from now on, look for the silhouette sign.
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100 Felson’s Principles of Chest Roentgenology
FIGURE 6-16
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Six • The Silhouette Sign 101
REVIEW
I
From the following descriptions of PA films, localize the lesion.
(a) Lung consolidation obscures the left heart border:
_______________
(b) Lung consolidation obliterates the aortic knob:
_______________
(c) A right lung base pneumonia fails to obliterate the heart:
_______________
(d) A right lung base pneumonia obliterates the heart:
_______________
(e) A pneumonia obscures the descending aorta:
_______________
II
Let’s review exceptions or false (+) silhouette signs.
A. A pseudosilhouette sign of the diaphragm may occur on
an [over/under]penetrated radiograph. The radiograph
is too [light/dark].
B. If the heart is positioned slightly to the left, the right
heart border may not be seen because _______________.
C. On the lateral radiograph, the heart normally obscures
the _______________.
III
In Figure 6-16, the patient has pneumococcal pneumonia.
Without a lateral, determine which lobe(s) is(are) consolidated.
_______________
How did you decide? _______________.
I
(a) lingula
(b) left upper lobe
(c) right lower lobe
(probably)
(d) right middle lobe
(e) left lower lobe
II
A. under; light
B. it overlaps the spine
C. anterior left
diaphragm
III
right middle lobe, right
lower lobe, lingula
Right and left heart sil-
houette signs and right
diaphragm silhouette
sign. Left diaphragm is
visible
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102 Felson’s Principles of Chest Roentgenology
FIGURE 7-1 A
FIGURE 7-1 B
FIGURE 7-1 C
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103
SEVEN
THE AIR
BRONCHOGRAM SIGN
On the normal chest x-ray, we see air in the trachea and proximal bronchi because they are
surrounded by the soft tissue (water density) of the mediastinum. In the lungs, however,
the bronchi are not visible. The only branching structures visible in the lungs are the 
pulmonary vessels (water density) surrounded by air.
1
The linear markings seen in the lungs are basically blood vessels,
which are __________ density. Because bronchi have very thin
walls, contain air, and are surrounded by air-filled alveoli, the
intraparenchymal bronchi [are/are not] visible on a normal
chest x-ray.
1
water (soft tissue)
are not
In Figure 7-1A, the branching pulmonary vessels are visible in the lung. The trachea
and proximal main bronchi (arrows) are surrounded by mediastinal soft tissue
and are visible. The peripheral bronchi are not visible. On CT, the bronchi are
normally visible through much of the lung. In Figure 7-1B, right lower lobe
bronchi appear tubular (in plane) and left lower lobe bronchi appear circular
(perpendicular to plane). Figure 7-1C, a coronal CT reconstruction, shows the
distal trachea, carina, and intraparenchymal bronchi (in plane).
2
To visualize the bronchi, we used to instill an opaque material
(iodinated oil) into the bronchial lumen. The “positive” contrast
bronchogram is seldom performed now because patients
[loved/hated] having thick oily goop dumped into their bronchi.
2
hated
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104 Felson’s Principles of Chest Roentgenology
FIGURE 7-2 A
FIGURE 7-2 B
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Seven • The Air Bronchogram Sign 105
3
Do we ever see normal bronchi on a chest x-ray? Sure we do!
When the lung is consolidated and the bronchi contain air, the
dense lung delineates the air-filled bronchi. Visualization of air
in the intrapulmonary bronchi on a chest roentgenogram is
called the air bronchogram sign. The presence of an air bron-
chogram indicates [normal/abnormal] lung.
3
abnormal
Figure 7-2A shows a bronchogram with iodinated contrast medium filling normal
medial bronchi and dilated lateral bronchi (bronchiectasis). CT has replaced
bronchography. In a different patient, Figure 7-2B shows multiple dilated bronchi
in cross section on the left and relatively normal bronchi on the right. Figure 7-2C
is a coronal CT scan that shows the left lower lobe bronchiectasis.
FIGURE 7-2 C
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106 Felson’s Principles of Chest Roentgenology
FIGURE 7-3 A FIGURE 7-3 B
FIGURE 7-4 FIGURE 7-5
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Seven • The Air Bronchogram Sign 107
4
Figure 7-3A simulates the normal lung with straws. Straw V
(vessel) contains water, and straw B (bronchus) contains air.
They are x-rayed in air. Straw _____________ is easily seen.
Straw _________ is much less visible because of ____________.
5
Figure 7-3B portrays a diseased (consolidated) lung; the straws
are immersed in water. Straw B is now ________, the ________
sign. Straw V now disappears, the ________ sign. If you missed
this, review questions 1-5.
4
V
B; air inside and 
outside the thin-walled
straw
5
visible; air bronchogram
silhouette
Figure 7-4 is a scout view of a patient with left lower lobe pneumonia. The bronchi
appear as branching black tubes in the consolidated lung behind the heart. 
In Figure 7-5, the CT scan shows a right middle lobe air bronchogram. Mild 
consolidation elsewhere does not give an air bronchogram.
6 6
“Doctors without 
borders”
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108 Felson’s Principles of Chest Roentgenology
FIGURE 7-6 FIGURE 7-7
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Seven • The Air Bronchogram Sign 109
7
Soft tissue and air density are involved in the air bronchogram
and silhouette sign. If an air-filled bronchus is to be seen, 
it must be surrounded by ____________ density. Conversely, if 
a pulmonary vessel is to be seen, it must be surrounded 
by _________. Not seeing the lung vessels is a variation of the
silhouette sign.
7
soft tissue (water)
(increased)
air
Figure 7-6 is a radiograph of a patient with generalized alveolar consolidation.
Many bronchi are visible, but the pulmonary vessels are not. Arrows indicate air
bronchograms in both upper lobes and the right lower lobe.
8
What good is the air bronchogram sign? Well, for one thing,
bronchi are pulmonary structures; visualization of the bronchi
(air bronchogram) indicates a ____________ lesion, rather than
a pleural or mediastinal lesion. It means that the bronchi 
contain ___________ and the adjacent lung is _____________.
8
pulmonary
air; consolidated (radio-
dense)
Figure 7-7 shows a dense area of consolidation with air-filled bronchi (arrows).
Because there is an air bronchogram sign, we know the lesion is in the lung 
and not in the mediastinum. Individual vessels are not visible because they are
surrounded by water density.
9
The air bronchogram may be seen in pneumonia, pulmonary
edema, pulmonary infarction, and certain chronic lung lesions.
As long as the bronchi are __________ and the surrounding lung
is radiopaque (water density), a(n) _______________ sign will be
present.
9
air-filled
air bronchogram
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110 Felson’s Principles of Chest Roentgenology
FIGURE 7-8
FIGURE 7-9
FIGURE 7-10
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Seven • The Air Bronchogram Sign 111
10
Do we always see an air bronchogram with pulmonary parenchy-
mal consolidation? “Always,” of course, is _________ the answer
in medicine. If a bronchus is obstructed or filled with secretions,
a pulmonary lesion [would/would not] show an air bronchogram.10
never
would not
Patchy peripheral lung consolidation or interstitial disease usually does not cause
enough opacity to produce an air bronchogram. Conditions that hyperinflate the
lungs do not cause air bronchograms.
11
A. In pneumonia, if the bronchi are filled with secretions,
there [would/would not] be an air bronchogram within
the lesion.
B. If a cancer obstructs a bronchus, an air bronchogram
[would/ would not] be visible.
C. Interstitial fibrosis [would/would not] cause an air 
bronchogram.
D. Asthma [would/would not] cause an air bronchogram.
11
A. would not
B. would not
C. would not
D. would not
In Figure 7-8, there is no air bronchogram in the collapsed right upper lobe because
the bronchi are full of mucous plugs. Compare with Figure 7-7. In Figure 7-9, there
is no air bronchogram in the consolidated lingula because a tumor obstructs
the proximal bronchus, and the bronchial air has been replaced by secretions
or resorbed.
12
The presence of an air bronchogram indicates a ___________
lesion. The absence of an air bronchogram indicates the 
lesion may be [pulmonary/extrapulmonary/either pulmonary or 
extrapulmonary].
12
lung
either pulmonary or
extrapulmonary
Clinical Pearl: The heart shadow often obscures left lower lobe disease on an AP
or PA radiograph. Sometimes an air bronchogram seen through the cardiac
shadow is the most definitive sign of left lower lobe consolidation. In Figure 7-10,
air bronchograms (arrows) are visible through the density of the heart. There is
also a silhouette sign of the medial diaphragm.
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112 Felson’s Principles of Chest Roentgenology
FIGURE 7-11
FIGURE 7-12
FIGURE 7-13
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Seven • The Air Bronchogram Sign 113
13
So it’s easy! Remember, consolidated lobes may not show an air
bronchogram if:
A. The bronchi are full of secretions [true/false].
B. There is an aspirated foreign body in the bronchus
[true/false].
C. There is not complete lung consolidation [true/false].
D. The patient has only emphysema [true/false].
13
A. true
B. true
C. true
D. true
Clinical Pearl: An air bronchogram indicates open airways, strong evidence 
that the lung disease is not due to an obstructing tumor in a smoker.
14
Are there any other uses of the air bronchogram? If you see 
air-filled bronchi that are very crowded together, this is evidence
of lung [overexpansion/collapse]. The crowded air bronchograms
suggest this is [obstructive/nonobstructive] atelectasis. In
Figure 7-6, the bronchi are normally spaced, whereas in 
Figure 7-7, they are crowded.
15
Several diseases may cause bronchiectasis. Instead of tapering,
the bronchi ____________, as they course peripherally.
14
collapse (atelectasis)
nonobstructive
15
widen (dilate)
Bronchiectasis is difficult to diagnose and illustrate on an x-ray. Figure 7-11
shows dilated bronchi (arrows) at the lung base. Figure 7-12 shows dilated, thick-
ened bronchi. Bronchi running in the axial plane are tubular (straight arrows),
and bronchi running across (perpendicular to) the axial plane are circular
(curved arrow). Figure 7-13 shows dilated bronchi completely filled with secre-
tions in plane (straight arrows) and in cross section (curved arrow).
Anagram: Rearrange the letters in DORMITORY to form two words that better
define it (answer on next page).
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114 Felson’s Principles of Chest Roentgenology
FIGURE 7-14 A FIGURE 7-14 B
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Seven • The Air Bronchogram Sign 115
REVIEW
I
Any tubular structure (bronchus, vessel), viewed longitudinally,
looks _____________. The same structure seen on end appears
__________. The inside of the bronchus is radiolucent because
__________, whereas the inside of a vessel is ____________
because it contains blood.
II
Which of the following conditions may show an air bronchogram?
(a) tuberculosis
(b) empyema
(c) emphysema
(d) mediastinal bronchogenic cyst
(e) bacterial pneumonia
(f) adult respiratory distress syndrome (ARDS)
III
A. Bronchi crowded together indicate _______________.
B. Dilated bronchi indicate ______________.
C. If an air bronchogram is visible, an endobronchial tumor
is ________________.
IV
Figures 7-14A and 7-14B are two postoperative patients with
shortness of breath.
A. Both show consolidation of the ____________ lobe.
B. The sharp demarcation between normal and abnormal
lung is the ______________.
C. Air is seen in the bronchi of [Figure 7-14A/Figure 7-14B].
This is the ______________ sign.
D. There is no air bronchogram sign in Figure 7-14B because
of _______________.
E. Which patient would benefit little from endobronchial
suction or bronchoscopy? ______________
I
linear, tubular
circular
it contains air;
radiodense or radiopaque
(water density)
II
(a) tuberculosis
(e) bacterial pneumonia
(f) ARDS
III
A. collapse, atelectasis
B. bronchiectasis
C. very unlikely
IV
A. right lower
B. major fissure
C. Figure 7-14A; air
bronchogram
D. mucus in the bronchi
E. Figure 7-14A (no
mucus to suction)
Anagram: DORMITORY = Dirty Room
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116 Felson’s Principles of Chest Roentgenology
FIGURE 8-1
a
b
c
FIGURE 8-2 A
d
e
FIGURE 8-2 B
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117
EIGHT
SIGNS OF LUNG AND
LOBAR COLLAPSE
Detecting signs of collapse within the lung is important in the diagnosis of lung disease. 
For us, it is also a good way to reinforce the anatomy. In general, the term “collapse” is used
to describe marked decreased volume of a lung, a lobe, or a segment. “Atelectasis” 
or “volume loss” is often used to describe less severe changes. The terms are fuzzy and
interchangeable (hard to believe). First, let’s look at the patterns of collapse on x-ray and CT
and then possible mechanisms.
1
When a whole lung collapses, the volume diminishes, and adjacent
structures move toward that lung. In Figure 8-1, the left lung is 
consolidated and collapsed. The trachea is [midline/left of 
midline/right of midline]. The heart has disappeared because
[it shifted left/it shifted right/there is Nocardia]. If the diaphragm
were visible, it would be [elevated/depressed/in a normal 
position].
2
The fissures that divide the lobes are formed by [two parietal
pleural layers/two visceral pleural layers/one visceral pleural
layer/one parietal pleural layer].
3
Because fissures demarcate the boundaries of the lobes, the
best sign of lobar collapse is shift of the fissures. Look at
Figures 8-2A and 8-2B and decide which lobe has collapsed.
(a) ________________________
(b) ________________________
(c) ________________________
(d) ________________________
(e) ________________________
1
left of midline
it shifted left
elevated
2
two visceral pleural
layers
3
(a) right upper lobe
(b) right middle lobe
(c) right lower lobe
(d) left upper lobe
(e) left lower lobe
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118 Felson’s Principles of Chest Roentgenology
FIGURE 8-3 B
FIGURE 8-3 A
FIGURE 8-4 A
FIGURE 8-4 B
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Eight • Signs of Lung and Lobar Collapse 119
4
Let’s try this for real. In Figure 8-3, there is consolidation of 
the ____________ lobe. The sharp inferior margin is caused by
the ____________. It is [elevated/depressed/normal] in position.
The accompanying CT scan shows collapse of the right upper
lobe, and the arrow points to an endobronchial tumor obstructing
the right upper lobe bronchus.
5
In Figure 8-4A, the position of the minor fissure is [inferior/
superior/unchanged]. The position of the major fissure is 
[anterior/posterior/unchanged]. There is a triangular density
over the heart. This is the collapsed __________ lobe.
In Figure 8-4B, there is a silhouette sign of the _________, caused
by ___________.
6
The diagnosis of right middle lobe collapse is often easier 
on the [frontal/lateral] view. Changes on the frontal radiograph
are often subtle. A triangular density, similar to right middle
lobe collapse,may be present on the lateral, with collapse 
of the ______________.
4
right upper
minor fissure; elevated
5
inferior
anterior
right middle
right heart border; 
right middle lobe 
consolidation
6
lateral
lingula
Figure 8-5 shows collapse of two lobes on the right. The minor fissure is elevated.
The right upper lobe is partially collapsed. There is a silhouette sign of the right
diaphragm, and the heart has moved to the right, indicating right lower lobe 
collapse. The right middle lobe remains aerated. We see the undersurface of 
the minor fissure and the right heart border because the right middle lobe is 
aerated.
FIGURE 8-5
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120 Felson’s Principles of Chest Roentgenology
FIGURE 8-6 A
FIGURE 8-6 B
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Eight • Signs of Lung and Lobar Collapse 121
7
In Figure 8-6A, let’s start with the lateral. The arrows point
to the [minor fissure/major fissure/azygos fissure]. The fissure
is displaced [anteriorly/posteriorly/unchanged]. On the frontal
view (Figure 8-6B), there is a mass in the left hilum, and the left
diaphragm is ________________. This is a case of total collapse
of the ______________________.
7
major fissure
anteriorly
elevated
left upper lobe (includ-
ing lingula)
The left upper lobe and lingula share a common bronchus. It is common for an
endobronchial lesion (tumor, foreign body, mucus) to obstruct them together. In
Figure 8-6A, the upper arrow is at the level of the upper lobe, and the lower
arrow is at the level of the lingula.
8
Similarly, the bronchus intermedius on the right supplies 
the right _________ and _________ lobes. These two lobes often
collapse together. Figure 8-7 shows dense consolidation at the
right base. The minor fissure is [elevated/depressed/normal].
There are silhouette signs of the ___________ and __________.
The right [upper/middle/lower] lobe(s) is(are) collapsed.
9
The [left upper lobe/lingula/left lower lobe] share a common
bronchus. On the right, the middle and lower lobes share a
common bronchus, called the _____________. A complete obstruc-
tion of either bronchus causes collapse of [one/two/three] lobes.
8
middle; lower
depressed
diaphragm; right heart;
middle and lower
9
left upper lobe and 
lingula
bronchus intermedius
two
Movement of the fissures is the most reliable sign of lobar collapse. Crowding 
of pulmonary vessels or bronchi and movement of parenchymal landmarks 
(e.g., nodules, granulomas, surgical clips) also can indicate volume loss.
FIGURE 8-7
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122 Felson’s Principles of Chest Roentgenology
FIGURE 8-8
FIGURE 8-9 A FIGURE 8-9 B
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Eight • Signs of Lung and Lobar Collapse 123
10
If a lobe or segment is atelectatic, but still contains some air,
the vascular markings would be visible, but in a [smaller/larger]
volume. If the lung is consolidated, the air bronchogram sign
might show us the bronchi. In either case, the vessels or bronchi
would appear [further apart/crowded together].
10
smaller
crowded together
Figure 8-8 shows crowded air bronchograms in left lower lobe collapse (arrows).
The collapsed lung is difficult to see behind the heart. There is a silhouette sign
of the left diaphragm.
11
In Figure 8-9A, there is a nodule in the right upper lobe. In
Figure 8-9B, after a needle biopsy, the nodule position is
[unchanged/more lateral/more medial]. The nodule has moved
because the lung volume is [static/increased/decreased]. The
nodule moved medially because there is now air in the pleural
space (pneumothorax) (arrow). (Yes, I did the biopsy.) Moving
“marker” structures may indicate volume loss.
12
The best and most frequent sign of lobar collapse is _________.
Two less frequent signs of lung collapse are _______________
and ________________.
11
more medial
decreased
12
fissure movement
crowded bronchi and
vessels
moving marker structures
The above-mentioned signs are direct signs of lobar collapse. There are several
less specific signs, such as shift of adjacent structures and change in lung 
density.
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124 Felson’s Principles of Chest Roentgenology
FIGURE 8-10
FIGURE 8-11
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Eight • Signs of Lung and Lobar Collapse 125
13
Hilar depression indicates collapse of a(n) [upper/lower] lobe.
Hilar elevation indicates collapse of a(n) [upper/lower] lobe.
Middle lobe or ____________ atelectasis usually does not shift
the hilum. Hilar shift is a reliable indirect sign of atelectasis.
13
lower
upper
lingular
To appreciate hilar displacement, one must know the relative positions of the
normal hila. In more than 97% of individuals, the left hilum (L) is slightly higher
than the right (R) (Figure 8-10). In the remaining 3%, the hila are at the same
level. Figures are based on 1000 normal chest x-rays studied by Dr. Felson when
he had nothing better to do (World War II noncombat overseas assignment, wife
in the U.S., and pre-television).
14
The indirect signs rely on shift of structures [toward/away
from] the collapsed lung. For instance, in lobar atelectasis, the
diaphragm is often [elevated/depressed]. By the way, which
diaphragm is usually higher? ___________.
Similarly, mediastinal structures may shift. With upper lobe 
collapse, the trachea shifts toward the lesion (see Figure 8-5).
With [lower/upper] lobe collapse, the heart may shift toward
the side of collapse (see Figure 8-5).
14
toward
elevated
the right, by a few cen-
timeters
lower
Volume loss usually changes the density of the lung. The airless, atelectatic lung
is more radiopaque, and adjacent lobes may hyperinflate to fill the void. This
“compensatory hyperinflation” causes the aerated lobe to be more radiolucent.
15
In Figure 8-11:
A. The left upper lobe is ____________ radiolucent than the
right upper lobe.
B. The left hilum is [higher than/lower than/the same level
as] the right.
C. The ______________ diaphragm is elevated.
D. There is an air bronchogram in the _______________.
E. Diagnosis: __________________
15
A. more
B. the same as
C. left
D. left lower lobe
E. left lower lobe 
collapse
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126 Felson’s Principles of Chest Roentgenology
FIGURE 8-12 A
FIGURE 8-12 B
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Eight • Signs of Lung and Lobar Collapse 127
16
If the airway is obstructed, air distal to the obstruction is
___________. Obstruction may be central (i.e., a lesion blocking
a main, lobar, or segmental bronchus) or peripheral (e.g.,
multiple small mucous plugs, blood clots) in small bronchi. 
Air distal to any obstruction is resorbed, and that portion of 
the lung _____________.
17
When the obstruction is central, it may be due to a lesion in the
bronchus causing intrinsic obstruction or an external lesion
compressing the bronchus, causing extrinsic obstruction.
(1) In Figure 8-12A, the right upper lobe collapse (C) is due
to _________, causing [intrinsic/extrinsic] obstruction.
(2) In Figure 8-12B, there is bronchial narrowing that is due 
to [intrinsic/extrinsic] obstruction.
16
resorbed
collapses (becomes
atelectatic)
17
(1) endobronchial
obstruction; intrinsic
(2) extrinsic (tumor
around bronchus)
The natural tendency of the lung is to collapse. Various physiologic mechanisms
keep the lung expanded. When one or more fails, the lung tends to lose volume.
There are five basic mechanisms that cause volume loss: (1) resorption of air as
a result of obstruction of a bronchus; (2) relaxation of the lung as a result of air
or fluid in the pleural space; (3) scarring, causing lung contraction; (4) decreased
surfactant reducing lung distensibility (adhesive atelectasis); and (5) hypoventila-
tion as a result of central nervous system depression or pain. 
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128 Felson’s Principles of Chest Roentgenology
FIGURE 8-13 A
FIGURE 8-13 B
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Eight • Signs of Lung and Lobar Collapse129
18
Figures 8-13A and 8-13B show postoperative atelectasis.
(1) Central obstructive atelectasis is seen in Figure 8- ______.
How did you decide? ___________. The most likely cause
is _________.
(2) In Figure 8-13B, there is postoperative collapse of
____________. Air bronchograms are [present/absent].
Collapse must be due to peripheral mucous plugging 
or hypoventilation.
19
Figure 8-14 is a coronal CT reconstruction showing a large
[pneumothorax/hydrothorax]. The central lucency (C) is the
collapsed right lung. The mechanism is known as ____________
or __________ atelectasis. Fluid in the pleural space or ________
in the pleural space causes this type of atelectasis.
18
(1) 13A; no air bron-
chogram; mucus in
airway
(2) both lower lobes;
present
19
hydrothorax
passive; relaxation; 
air
Clinical Pearl: In children, central obstruction is often due to a mucous plug or
an aspirated foreign body. In adults younger than 40 years old, it is usually due
to a mucous plug, a foreign body, or a low-grade endobronchial tumor (adenoma,
carcinoid). In adults older than age 40, bronchogenic carcinoma is a frequent
cause of postobstructive collapse.
FIGURE 8-14
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130 Felson’s Principles of Chest Roentgenology
FIGURE 8-15
FIGURE 8-16
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Eight • Signs of Lung and Lobar Collapse 131
20
Pulmonary fibrosis, either local (e.g., tuberculous scarring,
radiation fibrosis) or generalized (e.g., silicosis, sarcoidosis),
results in diminution in volume. In Figure 8-15, the [right/left]
hilum is [elevated/depressed/normal]. The minor tissue is 
elevated (arrows). The trachea is ________. These signs indi-
cate collapse of the ____________ lobe. This is termed
___________ atelectasis.
21
Surfactant diminishes surface tension in the alveoli, making it
easier to inflate the lung. Diminished surfactant promotes
volume loss. This is termed _____________ atelectasis. Name a
disease or condition that causes adhesive atelectasis: ________.
20
right
elevated
shifted right
right upper; cicatriza-
tion (scarring)
21
adhesive; respiratory
distress syndrome of
the newborn, adult 
respiratory distress syn-
drome (ARDS), uremia,
cardiac bypass surgery
Clinical Pearl: Hypoventilation atelectasis is frequent after general anesthesia
or heavy sedation. It most often involves the lung base.
22
State the mechanism of atelectasis for the following conditions:
(a) An aspirated peanut causes [intrinsic/extrinsic] obstruc-
tion, an example of [central/peripheral] resorptive
atelectasis.
(b) A sedative overdose causes _________ atelectasis.
(c) A hemothorax causes _________ atelectasis.
(d) Radiation fibrosis causes __________ atelectasis.
(e) Adenopathy from lymphoma causes [intrinsic/extrinsic]
bronchial compression leading to [central/peripheral]
resorptive atelectasis.
Atelectasis also can occur at the segmental level or in random
small areas of the lung parenchyma. This usually presents as a
linear band of dense lung, often referred to as plate or bandlike
atelectasis. Figure 8-16 shows bandlike atelectasis at the lung
base caused by hypoventilation.
22
(a) intrinsic; central
(b) hypoventilation
(c) relaxation (passive)
(d) cicatricial
(e) extrinsic; central
Anagram: Twelve plus one = ___________________.
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132 Felson’s Principles of Chest Roentgenology
FIGURE 8-17 A
FIGURE 8-17 B
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Eight • Signs of Lung and Lobar Collapse 133
REVIEW
I
Figure 8-17A is an x-ray of a patient 8 hours after general 
surgery. This is a chance for you to pull together what you have
learned in the last several chapters.
A. Which lobes are collapsed? _________ and __________.
B. Direct signs? ___________.
C. Indirect signs? __________.
D. Air bronchograms are [present/absent], indicating
___________.
E. Silhouette sign—where? ___________.
II
Figure 8-17B is an x-ray of another patient, several hours after
surgery.
A. Which lobes are collapsed? ___________ and __________.
B. Direct signs? _____________.
C. Indirect signs? ____________.
D. Air bronchograms are [present/absent].
E. Silhouette sign—where? ______________ and __________.
I
A. right middle lobe;
right lower lobe
B. minor fissure down
C. mediastinal shift,
upper lobe hyperin-
flated, right middle
lobe and right lower
lobe radiopaque
D. absent; mucus in
major bronchi
E. diaphragm, right
heart
II
A. left upper lobe; 
lingula
B. none
C. elevated diaphragm,
heart shifted left,
increased density
D. absent
E. left heart border;
mediastinum
Anagram: Twelve plus one = eleven plus two.
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134 Felson’s Principles of Chest Roentgenology
FIGURE 9-1 A
FIGURE 9-1 B
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135
NINE
PATTERNS OF LUNG
DISEASE
We have already seen how disease can consolidate or collapse a segment or lobe. We now
look at other patterns of diffuse and focal lung disease. The lung reacts to disease in a
limited number of ways. The interstitium can thicken or thin, and the alveoli can fill 
with fluid or extra air. These changes may be focal or diffuse. They may be acute or chronic.
This leads to 16 possible combinations (interstitium = thick/thin) × (alveoli = fluid/air)
× (location = focal/diffuse) × (time = acute/chronic). Relax. We concentrate only on the most
common combinations. These four basic variables help us analyze the chest x-ray and form
a differential diagnosis.
1
First, a brief review. For each chest radiograph, we ask, 
“Are There Many Lung Lesions?”
A = _____________
T = _____________
M = _____________
L = _____________
L = _____________
Review the search patterns outlined in Chapter 3, if necessary.
2
Conceptually, the lung has two components, the supporting
structures (e.g., arteries, veins, bronchi), known as the
_____________, and the air sacs known as the _____________. 
Air sacs form acini, and several acini form a _____________.
Review Figures 9-1A and 9-1B.
3
On a normal chest x-ray (Figure 9-1A), the “interstitium” is
basically the branching _____________. As they branch, they
disappear peripherally because they are _____________.
1
A = abdomen
T = thorax (bones and
soft tissue)
M = mediastinum
L = lung—unilateral
L = lung—bilateral
2
interstitium; alveoli
secondary pulmonary
lobule
3
pulmonary vessels
beyond the resolution
of the x-ray
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136 Felson’s Principles of Chest Roentgenology
FIGURE 9-2 A
FIGURE 9-3 A
FIGURE 9-3 B
FIGURE 9-2 C
FIGURE 9-2 B
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Nine • Patterns of Lung Disease 137
4
The normal air-filled alveoli (air sacs) are too small to resolve,
but in total they appear uniformly [radiolucent/radiodense].
5
Match the following descriptions with the CT patterns shown in
Figures 9-3A and 9-3B.
(1) normal = _____________
(2) alveolar filling disease = _____________
(3) linear (reticular) interstitial thickening = _____________
(4) nodular interstitial thickening = _____________
4
radiolucent black
5
(1) B
(2) C
(3) A
(4) D
Most lung diseases result in increased radiodensity of the lung. If the intersti-
tium thickens, it can be seen more peripherally on the x-ray or CT scan. If the
interstitial thickening is generalized, the pattern is linear (reticular) (Figure 9-2A).
If the thickening is discrete, it forms multiple nodules (Figure 9-2B). If the alveoli
fill with fluid, the fluid-filled area becomes radiodense, and the interstitium is
enveloped in the dense white lung and is not visible (Figure 9-2C).
In your mind’s eye (whatever that is), fuse the patterns in Figure 9-2 with those
in Figure 9-3.
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138 Felson’s Principles of Chest Roentgenology
FIGURE 9-4 A FIGURE 9-4 B
FIGURE 9-4 C
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Nine • Patterns of Lung Disease 139
6
Match the patterns listed with the patterns illustrated in
Figures 9-4A, 9-4B, and 9-4C.
(1) alveolar filling disease =_____________
(2) reticular (linear) interstitial thickening = _____________
(3) nodular interstitial thickening = _____________
7
Let us start to look at the specific patterns. In interstitial lung
disease, if the peribronchovascular tissue thickens, the vessels
or “markings” appear [more/less] prominent. At the same time,
the alveoli are still _____________. The basic appearance is one
of aerated lung but with too many “markings.”
8
Figures 9-4A and 9-4B show prominent interstitial markings,
which may be in one area of the lung (focal) or generalized
(diffuse).
1. In Figure 9-4A, the dominant pattern is [linear/nodular]
and [diffuse/focal].
2. In Figure 9-4B, the dominant pattern is [linear/nodular]
and [diffuse/focal].
9
In general, acute and chronic interstitial lung diseases look
similar. If the markings are hazy (ill defined) and not distorted
(i.e., normal branching pattern), the disease is probably
[acute/chronic]. If the lung markings are sharp (well defined)
and distorted (i.e., angular, irregular, bowed), the disease is
probably [acute/chronic].
6
(1) Figure 9-4C
(2) Figure 9-4A
(3) Figure 9-4B
7
more
aerated
8
1. linear
focal
2. nodular
diffuse
9
acute
chronic
Clinical Pearl: Most diffuse interstitial lung disease is chronic and usually due
to fibrosis. Acute diffuse interstitial lung disease is usually due to pulmonary
edema and viral/mycoplasmal pneumonia.
Clinical Pearl: The most reliable method of distinguishing acute from chronic is
by viewing past films or, heaven forbid, taking a history. Neither is cheating. 
It is synthesizing information to arrive at the best possible answer for the patient.
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140 Felson’s Principles of Chest Roentgenology
FIGURE 9-5 A
FIGURE 9-6 A
FIGURE 9-5 B
FIGURE 9-6 B
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Nine • Patterns of Lung Disease 141
10
Figure 9-5A shows diffuse interstitial lung disease. The “intersti-
tial” markings are [increased/decreased], whereas the alveoli
are [aerated/airless]. It is chronic because the markings are
[distorted/not distorted] and [distinct/indistinct]. In Figure 9-5B,
the CT scan shows distorted and sharp interstitium and aerated
lung.
11
Match the patterns with the likely cause:
Pattern
1. Interstitial markings are thickened = _____________
2. Interstitial markings are very sharp = _____________
3. Interstitial markings are indistinct = _____________
4. Interstitial markings are distorted = _____________
5. Interstitial markings change over several days = ________
Likely Cause
(A) acute
(B) chronic
(C) acute or chronic
10
increased
aerated
distorted; distinct
11
1. C
2. B
3. A
4. B
5. A
Another form of fibrosis is “honeycombing.” The fibrosis forms multiple small
cysts, often stacked up one on another, just beneath the pleura. Figures 9-6A and
9-6B show an x-ray and CT scan with honeycombing.
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142 Felson’s Principles of Chest Roentgenology
FIGURE 9-7
FIGURE 9-8
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Nine • Patterns of Lung Disease 143
12
In Figure 9-7, there is [alveolar/interstitial] disease. The normal
interstitial markings [are/are not] visible within the consoli-
dated areas. This concept is similar to the [silhouette sign/air
bronchogram sign] because water density lung is in direct
contact with the water density pulmonary vessels (interstitium).
13
Alveolar consolidation causes a silhouette sign with the
diaphragm, heart, or aorta only if they are _____________. The
silhouette sign is usually [present/absent] in interstitial disease
because _____________ is adjacent to these structures.
14
The air bronchogram (remember the air bronchogram?) is usu-
ally seen in [alveolar/interstitial] disease because the major air-
ways are [open/plugged] but surrounded by consolidated
(water density) lung. In interstitial disease, the bronchi are still
surrounded by _____________.
12
alveolar
are not
silhouette sign
13
in direct contact
absent
aerated lung
14
alveolar
open
aerated lung
We have just learned that most diffuse interstitial lung disease is chronic. 
Most alveolar disease (airspace consolidation), whether focal, multifocal, or
diffuse, is acute. With alveolar disease, the airspaces are filled with fluid 
(e.g., edema, blood, mucus, pus, or cells), making the lung appear airless 
(radiodense, opaque, consolidated). The alveolar pattern may be relatively
homogeneous (a lobe or segment) or patchy and scattered throughout the lung.
Figure 9-8 shows airspace consolidation of the right upper lobe, an air bron-
chogram (arrows), and a silhouette sign of the upper heart and mediastinum—
three important signs of alveolar filling disease. There is also focal
consolidation of the right lower lobe without an air bronchogram or silhouette
sign.
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144 Felson’s Principles of Chest Roentgenology
FIGURE 9-9
FIGURE 9-10 A
FIGURE 9-10 B
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Nine • Patterns of Lung Disease 145
15
To recap:
(a) With alveolar consolidation, the air bronchogram is
absent if _____________.
(b) With alveolar consolidation, the silhouette sign is absent
if _____________.
(c) The air bronchogram and silhouette signs are usually
signs of _____________.
16
Figure 9-9 is an example of multifocal alveolar disease. Within
the areas of consolidation, the interstitial markings are [visible/
not visible]. Air bronchograms are more frequently absent in
[large/small] areas of alveolar consolidation. The age of the
lesion is assessed most accurately with _____________. History
is helpful but less reliable.
15
(a) fluid fills the
bronchi (or central
obstruction)
(b) The consolidation is
not in direct contact
with water density
structure
(c) alveolar (airspace)
consolidation
16
not visible
small
old radiographs
Clinical Pearl: The most frequent causes of acute diffuse alveolar disease
(airspace filling disease) are bacterial pneumonia and severe pulmonary
edema. The most frequent cause of acute focal alveolar consolidation is also
infection. Subacute alveolar consolidation is often granulomatous infection
(tuberculosis, fungal).
To make life difficult, some diseases have alveolar consolidation and interstitial
thickening. Figure 9-10A shows focal left upper lobe alveolar consolidation 
and diffuse interstitial thickening in a patient with silicosis. Figure 9-10B shows
the two patterns nicely. Note the interstitium is sharp and distorted.
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146 Felson’s Principles of Chest Roentgenology
FIGURE 9-11 A FIGURE 9-11 B
FIGURE 9-12
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Nine • Patterns of Lung Disease 147
17
In Figure 9-11A, there are two focal [alveolar/interstitial]
opacities on the right. They have [distinct/indistinct] margins.
18
(1) In Figure 9-11A, the larger opacity (A) measures greater
than 3 cm. It is termed a _____________.
(2) In Figure 9-11A, the smaller opacity (B) measures 1.2 cm
and is termed a _____________.
(3) In Figure 9-11B, just above the diaphragm, there is a
_____________.
19
When any alveolar lesion (infiltrate, mass, nodule) becomes
necrotic or caseous, the liquefied material is usually expecto-
rated and replaced with _____________. The center of the cavity
becomes [radiodense/radiolucent].
17
alveolar
distinct
18
(1) mass
(2) nodule
(3) spot on the lung
19
air
radiolucent
An important form of focal alveolar consolidation is the mass or nodule 
(the famous “spot on the lung”). If a very focal area of consolidation has 
well-defined borders and measures greater than 3 cm, it is referred to as a
“mass.” If it is less than 3 cm, it is called a “nodule.”
Clinical Pearl: In young patients, chronic alveolar consolidation, nodules, and
masses are most often due to indolent infection or inflammatory lung disease. 
In patients older than age 40, cancer becomes a major concern.
Figure 9-12 shows multiple masses, two of which are cavitary (arrows).
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148 Felson’s Principles of Chest Roentgenology
FIGURE 9-13 A
FIGURE 9-14 FIGURE 9-15 A FIGURE 9-15 B
FIGURE 9-13 B
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Nine • Patterns of Lung Disease 149
20
If the necrotic material is only partially expelled, air and fluid
remain in the cavity. When the patient is erect, the fluid settles
to the bottom, and the air rises to the top. This air-fluid level 
is visible only when the x-ray beam is [parallel/perpendicular]
to the air-fluid interface. An air-fluid level is not seen in
[erect/supine] radiographs, because _____________.
21
Figures 9-13A and 9-13B show x-rays of a Styrofoam cup half 
full of water. Which was taken with a horizontal x-ray 
beam? _____________. How did you decide? _____________. 
In Fig. 9-13B, the cup margin (arrow) is very sharp, but the
water margin (arrowhead) is less sharp. The top of the water
column is wider than the bottom. One is looking down at two
edges not quite superimposed.
22
In granulomatous infections, if caseous material is not expelled,
it may heal and organize into a granuloma. Granulomas
frequently calcify. Figure 9-15A shows a nodule in the left 
mid lung. It is [more dense/less dense] than the rib; therefore 
it is of _____________ density. This is most likely a [healed
scar/cancer/active tuberculosis]. Figure 9-15B shows the same
granuloma on CT.
20
parallel
supine; x-ray beam is
perpendicular to air-
fluid level
21
Figure 9-13A; parallel to
interface, see air-fluid
level
22
more dense
calcium, metallic
healed scar
Question: Is a glass half full or half empty? (1) It depends on who is pouring 
and who is drinking. (2) It is neither. The glass is just too big. (3) Half full = 1/2 ×
1 = 1/2. Half empty = 1/2 × 0 = 0, obviously wrong. (From geekswithblogs.net.)
Figure 9-14 shows an air-fluid level (arrow) in a cavitary right upper lobe
pneumonia. Compare with Figure 9-12, where there is no fluid in the cavities.
Clinical Pearl: Heavy calcification is an important sign of benign disease in 
the lung. Healed tuberculosis and histoplasmosis are the most frequent causes 
of lung granulomas. The adjacent hilar lymph nodes often calcify (Figure 9-15B).
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150 Felson’s Principles of Chest Roentgenology
FIGURE 9-16 A FIGURE 9-16 B
FIGURE 9-16 C
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Nine • Patterns of Lung Disease 151
23
On the frontal view, diaphragmatic changes indicate hyper-
inflation. In Figure 9-16A, the diaphragms are flat and
[normal/high/low]. They are lower than the _____________
posterior rib. The diaphragms are normally at the [7th-8th/
9th-10th//11th-12th] posterior rib.
24
Hyperinflation also is seen on the lateral. In Figure 9-16B, 
the sternum is [normal/bowed/sunken]. The “retrosternal 
clear space” (R), the area between the ascending aorta and 
the sternum, is [normal/increased/decreased]. The AP diame-
ter is increased (i.e., barrel chest). The diaphragms are
_____________ and _____________.
25
The combination of hyperinflation and _____________ indicates
emphysema.
In Figure 9-16C, note the cystic spaces and distortion caused by
the thin walled bulla.
23
low (depressed); 10th;
9th-10th (below 10th =
hyperinflation)
24
bowed
increased
flat; depressed (low)
25
bullae (sparse or
distorted markings or
lung destruction)
Few conditions cause the lung to be more radiolucent. If the lung is hyperin-
flated, it becomes hyperlucent because a fixed amount of tissue is spread over a
larger volume. If the interstitium is destroyed (e.g., bulla formation), the lung
becomes more hyperlucent because there is less tissue to absorb radiation.
Bullae or sparse markings replace normal branching vessels (Figure 9-16A).
In real life, these nice neat patterns of lung disease often overlap. However, this
approach provides a way of organizing your descriptions to form a differential
diagnosis.
Anagram: Snooze alarms = _____________.
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152 Felson’s Principles of Chest Roentgenology
FIGURE 9-17 A
FIGURE 9-17 B
FIGURE 9-17 C
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Nine • Patterns of Lung Disease 153
REVIEW
I
Radiologic signs of diffuse interstitial lung disease:
1. “Pulmonary markings” are [more/less] visible.
2. The lung appears [aerated/not aerated].
3. An air bronchogram is [often/seldom] visible.
4. The silhouette sign [is/is not/may be] visible.
5. Two signs of chronic disease include _____________ and
_____________.
II
Radiographic signs of alveolar filling disease or airspace con-
solidation:
1. Vessels are [more/less] visible in the area of disease.
2. The diseased lung appears [aerated/not aerated].
3. An air bronchogram [is/is not/may be] visible.
4. A silhouette sign [is/is not/may be] visible.
III
In Figures 9-17A and 9-17B, the patient has two diseases.
A. The patient has what generalized lung disease?
_____________.
B. There is also a _____________ in the _____________ lobe
(arrowheads on Figure 9-17B).
C. He has had one too many [drinks/cigarettes/lovers].
D. On Figure 9-17C, how does CT confirm your suspicions
about his x-ray findings and his personal habits? (Use all
the information on the film!) _____________.
E. The mass is almost certainly _____________.
I
1. more
2. aerated
3. seldom
4. is not
5. distortion, honey-
combing, sharp
margins, no serial
change
II
1. less
2. not aerated
3. may be
4. may be
III
A. chronic obstructive
pulmonary disease
(COPD) (emphysema)
B. mass, right upper
C. cigarettes
D. right upper lobe
mass, bulla, ciga-
rettes and lighter in
left breast pocket
E. lung cancer
Anagram: Snooze alarms = Alas, no more Z’s!
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154 Felson’s Principles of Chest Roentgenology
FIGURE 10-1 A
FIGURE 10-1 B
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155
TEN
THE MEDIASTINUM
The mediastinum is the area between the right and left lung, bounded by the medial 
parietal pleura. Mediastinal diseases can be difficult to detect on chest x-ray because most
diseases are of soft tissue density and are surrounded by other soft tissue structures.
Mediastinal lesions may cause local or diffuse widening; displace, compress, or invade
adjacent structures; or cause a silhouette sign with adjacent structures.
1
Let’s review the mediastinal borders. On Figure 10-1A, identify
the following:
A = _____________
B = _____________
C = _____________
D = _____________
E = _____________
F = _____________
G = _____________
(The left and right pulmonary arteries (L and R), which define
the hilum, are outside the mediastinum, in the lung.)
2
There is considerable overlap of the mediastinal structures in
the PA view. The lateral view is often helpful for localization. 
In Figure 10-1B, identify the following:
A = _____________
B = _____________
C = _____________
D = _____________
G = _____________
L = _____________
R = _____________
The lucent area (X) between the sternum and the ascending
aorta is called the _____________.
1
A = ascending aorta
B = aortic knob (arch)
C = descending aorta
D = right heart
E = superior vena cava
F = right tracheal wall
G = left heart
2
A = ascending aorta
B = aortic knob
C = descending aorta
D = right heart
G = left heart
L = left pulmonary artery
R = right pulmonary
artery
retrosternal clear space
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156 Felson’s Principles of Chest Roentgenology
FIGURE 10-2 A
FIGURE 10-2 B
FIGURE 10-2 C
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Ten • The Mediastinum 157
3
Let us review the CT anatomy of the mediastinum discussed in
Chapter 4. Figures 10-2A, 10-2B, and 10-2C are three CT scans.
They are at [mediastinal/lung/bone] windows. Intravenous
contrast medium [has/has not] been given.
4
Figure 10-2A is through the aortic arch. Identify:
A = _____________
B = _____________
C = _____________
D = _____________
* = _____________
F = _____________
5
Figure 10-2B is just below the carina. Identify:
E = _____________
F = _____________
G = _____________
H = _____________
J = _____________K = _____________
r = _____________
6
Figure 10-2C is through the heart. Identify:
L = _____________
M = _____________
N = _____________
O = _____________
P = _____________
7
The mediastinum completely separates the left and right
pleural spaces in every animal but the _____________. (“Man is
the missing link between animals and human beings.”—Konrad
Lorenz)
3
mediastinal; has
4
A = ascending aorta
B = descending aorta
C = superior vena cava
D = trachea
* = aortic arch
F = esophagus
5
E = main pulmonary
artery
F = left pulmonary
artery
G = ascending aorta
H = descending aorta
J = right main stem
bronchus
K = right hilum
(pulmonary vessels)
r = normal-sized
lymph nodes
6
L = right ventricle
M = left ventricle
N = descending aorta
O = dome of
diaphragm (liver)
P = esophagus
7
Lymph nodes of less than 1 cm are frequently seen on CT in normal individuals.
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158 Felson’s Principles of Chest Roentgenology
FIGURE 10-3 A
FIGURE 10-4 A FIGURE 10-4 B
FIGURE 10-3 B
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Ten • The Mediastinum 159
8
The most frequent sign of mediastinal disease is mediastinal
widening. Most masses cause [focal/generalized] widening.
Infiltrating diseases, such as hemorrhage or infection, usually
cause [focal/generalized] widening.
9
Figures 10-3A and 10-3B show two cases of mediastinal disease.
Which is likely due to tumor? _____________. Why?
_____________. Which is likely due to hemorrhage?
_____________. Why? _____________.
10
A mediastinal mass displaces the medial pleura toward the
lung. The interface with the lung is usually [sharp/indistinct]
and [concave/convex].
11
Masses in an enclosed space such as the mediastinum also 
may displace, compress, or invade adjacent mediastinal struc-
tures. In Figure 10-4A, the trachea is [midline/displaced], and its
lumen is [open/narrow]. In Figure 10-4B, the trachea is
[midline/displaced], and the lumen is [open/narrow].
8
focal
generalized
9
Figure 10-3A
tumor is focal
Figure 10-3B
hemorrhage is diffuse
10
sharp
convex (toward the
lung)
11
displaced
narrow
midline; narrow
(compressed)
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160 Felson’s Principles of Chest Roentgenology
FIGURE 10-5
FIGURE 10-6
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Ten • The Mediastinum 161
12
Finally, a mediastinal mass may obscure an adjacent structure
of the same density, the _____________ sign. This helps to
locate the mass. Figure 10-5 shows a large mass obliterating the
_____________ border. Because the trachea is in the middle
mediastinum, this is a _____________ mediastinal mass. Note
tracheal displacement and marked narrowing (arrows).
13
The radiologist divides the mediastinum into three compart-
ments based on the lateral chest x-ray. In Figure 10-6, an imagi-
nary line separates the anterior (I) and middle mediastinum (II).
The line sits in front of the trachea but behind the
_____________. A second line, 1 cm back from the anterior 
edge of the vertebral bodies, separates the _____________
mediastinum from the _____________ mediastinum.
14
The anterior mediastinal compartment sits between the sternum
and a line drawn anterior to the _____________ and posterior to
the _____________. On the lateral x-ray, the upper portion is the
area of the retrosternal clear space.
12
silhouette
right tracheal (right
mediastinal)
middle
13
heart
middle
posterior
14
trachea
heart
For convenience of differential diagnosis, the mediastinum is divided into three
compartments: anterior, middle, and posterior. There are several methods of
dividing the mediastinum. None is perfect because structures and diseases often
cross these artificial divisions. Felson’s is the simplest (and we like simple).
(“Get the facts first and then distort them as you please.”—Mark Twain)
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162 Felson’s Principles of Chest Roentgenology
FIGURE 10-7 A
FIGURE 10-7 B
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Ten • The Mediastinum 163
15
The lateral radiograph is often helpful in assigning disease to
one of the mediastinal compartments. In Figure 10-7A, the mass
sits in the _____________ mediastinum. It fills the retrosternal
clear space. (Compare with Figure 10-1B.)
16
What lesions cause anterior mediastinal masses? “Snow White
and the Seven Dwarfs” dwell in the forest. “Big White and the
Five T’s” dwell in the anterior mediastinum. Big White is the
_____________ and the five T’s are named Thyroid, Thymus,
Teratoma, Thoracic aorta (ascending), and Terrible lymphoma.
(Big White is discussed in Chapter 12.)
17
The anterior edge of the middle mediastinum is a line anterior
to the _____________ in the upper chest and posterior to the
_____________ in the lower chest. The posterior margin of the
middle mediastinum is formed by a line drawn _____________.
18
A review:
(1) Most mediastinal masses cause a _____________ widen-
ing of the mediastinum.
(2) Most mediastinal infiltration (blood, infection) causes a
_____________ widening of the mediastinum.
(3) In both cases, the interface with the lung is usually
[sharp/indistinct] and [toward/away from] the lung.
(4) Secondary signs of mediastinal disease include invasion,
_____________, _____________, and a _____________ sign.
15
anterior
16
heart
17
trachea
heart
1 cm behind anterior
edge of vertebral
bodies
18
(1) focal
(2) diffuse
(3) sharp; toward
(convex)
(4) displacement,
compression,
silhouette
Figures 10-3A and 10-7A show a thymic mass in the same patient. Generally, it is
difficult to differentiate one anterior mediastinal mass from another on the
chest x-ray. CT is often helpful in delineating boundaries. In Figure 10-7B, CT
shows a homogeneous anterior mediastinal thymic mass with sharp margins,
just anterior to the ascending aorta.
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164 Felson’s Principles of Chest Roentgenology
FIGURE 10-8 A
FIGURE 10-8 B
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Ten • The Mediastinum 165
19
Which of the following structures are located in the middle
mediastinum?
esophagus
lymph nodes
spinal nerves
heart
arch and descending aorta
trachea
20
In Figure 10-8A, there is a lobulated mass obscuring the right
tracheal border. The trachea is located in the _____________
mediastinum. This is a _____________ mediastinal mass. The
mass is _____________ toward the lung and is lobulated, but has
sharp borders.
21
The three major middle mediastinal organs are esophagus, tra-
chea, and aorta (arch and descending). Most middle mediastinal
masses arise, however, from the _____________.
19
esophagus
lymph nodes (in all
three compartments)
arch and descending
aorta
trachea
20
middle
middle
convex
21
lymph nodes
Figure 10-8B is a CT scan showing the enlarged lymph nodes to the right of 
and anterior to the trachea (T), in the middle mediastinum. The trachea is not
compressed.
Clinical Pearl: Enlarged lymph nodes are the most frequent cause of a middle
mediastinal mass. Middle mediastinal adenopathy is most often due to sarcoido-
sis in young patients and lung cancer in older patients.
To discourage thieves, the farmer posted a sign: “Caution, one of these cabbages
has been poisoned.” The next morning, he found the sign read: “Caution, two of
these cabbages have been poisoned.”
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166 Felson’s Principles of Chest Roentgenology
FIGURE 10-9 A
FIGURE 10-10 A
FIGURE 10-9 C
FIGURE 10-9 B
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Ten • The Mediastinum 167
22
In the middle mediastinum, if one suspects an esophageal
lesion, the appropriate examination would be [CT/barium swal-
low/MRI]. If one suspects a solid tumor, adenopathy, or a tra-
cheal lesion, the appropriate examination would be [CT/barium
swallow/MRI]. Figures 10-9A and 10-9B show an air-containing
mass behind the heart. Figure 10-9C is a lateral view of a barium
swallow (esophagram) showing the large hiatal hernia (stom-
ach above diaphragm). (E = esophagus; S = stomach.)
23
Don’t forget thatvascular structures also traverse the medi-
astinum. The ascending aorta is in the [anterior/middle/poste-
rior] mediastinum on the right, and the aortic arch is in the
[anterior/middle/posterior] mediastinum as it crosses from right
to left. The descending aorta usually sits anterolateral to the
anterior margin of the vertebral bodies. In Felson’s classification,
the descending aorta is a _____________ mediastinal structure.
As it elongates with age, it usually overlaps the spine on the lateral.
22
barium swallow
CT (or MRI)
23
anterior
middle
middle
FIGURE 10-10 B
Primary tracheal lesions are rare, but keep your eye on the trachea because 
it is often deviated or narrowed by adjacent lesions.
In Figure 10-10A, an aneurysmal aortic arch projects as a mass. Note the calci-
fied (atherosclerotic) intima of the aortic arch (upper arrow). The tortuous
descending aorta is lateral to the heart (lower arrow). Figure 10-10B shows the
tortuous descending aorta (arrow) overlapping the spine. A feeding tube shows
the normal course of the esophagus—a middle mediastinal structure.
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168 Felson’s Principles of Chest Roentgenology
FIGURE 10-11 A
FIGURE 10-11 B
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Ten • The Mediastinum 169
24
The posterior mediastinum sits between a line _____________
and the posterior ribs. More simply, the posterior mediastinum
is the paravertebral area.
25
In Figure 10-11A, a large mass overlies the spine. It may be in the
lung or in the _____________. The arrows point to a destroyed
and collapsed vertebral body, suggesting that this mass is in
the _____________. Figure 10-11B shows multiple myeloma of the
vertebral body producing the paraspinous mass and expanding
the vertebral body and adjacent rib (arrow = normal rib).
24
1 cm behind anterior
edge of the vertebral
bodies
25
posterior mediastinum
posterior mediastinum
Figure 10-12, an MRI image, shows a neural tumor. The vertebral body (V) is
intact, but a soft tissue mass (M) protrudes through the neural foramen into the
posterior mediastinum. The descending aorta (x) is normal.
Clinical Pearl: Most posterior mediastinal masses are from the nerves or their
coverings (e.g., neurofibroma, meningocele) in younger patients. Multiple
myeloma and metastatic spine diseases are more common in older patients.
Name the three birds of the mediastinum:
(1) esopho-goose; (2) azi-goose; (3) thoracic-duck
FIGURE 10-12
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170 Felson’s Principles of Chest Roentgenology
FIGURE 10-13 A
FIGURE 10-13 B
FIGURE 10-13 C
FIGURE 10-14
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Ten • The Mediastinum 171
26
Infection, hemorrhage, adenopathy, and infiltrating tumor may
involve several mediastinal compartments. This usually causes
a [focal/generalized] mediastinal widening.
27
The mediastinum sits [central/lateral] to the medial parietal
pleura. The hilum sits [inside/outside] the mediastinal pleura.
On the normal chest x-ray, the visible structures we call the
hilum are really the _____________. They taper as they course
peripherally. Normal hilar nodes are not visible on the chest 
x-ray. In Figure 10-14, there is bilateral hilar adenopathy. 
The hila are lumpy because of the enlarged nodes.
26
generalized
27
central
outside
pulmonary vessels
(arteries, veins)
In Figure 10-13A, there is diffuse widening of the mediastinum after trauma. 
In Figure 10-13B, the CT scan shows fluid (blood) surrounding the aortic 
arch. Figure 10-13C is a multiplanar reconstruction of the aorta, showing a 
post-traumatic pseudoaneurysm (arrow).
Clinical Pearl: The most common cause of a hilar mass is adenopathy or an
adjacent tumor.
The chest x-ray is reasonably sensitive in detecting mediastinal lesions.
Additional imaging usually is required to characterize the abnormality. This is
where your clinical understanding of the patient ’s history and physical findings
defines the next appropriate imaging test. There are many different examinations
to choose from. It is often helpful to check with the radiologist. You may even get
different answers from different radiologists.
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172 Felson’s Principles of Chest Roentgenology
FIGURE 10-15 A
FIGURE 10-15 C
FIGURE 10-15 B
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Ten • The Mediastinum 173
REVIEW
I
A. There are _____________ jokers in a deck.
B. There are _____________ stooges.
C. There are _____________ horsemen.
D. There are _____________ T’s in the anterior medi-
astinum.
The T’s are _____________, _____________, _____________,
_____________, and _____________.
II
For each named structure, give the mediastinal compartment:
1. esophagus: ____________________
2. heart: _________________________
3. thymus: _______________________
4. trachea: _______________________
5. thyroid: _______________________
6. spinal nerves: __________________
7. lymph nodes: __________________
8. aorta, ascending: _______________
9. aorta, descending: ______________
10. aortic arch: ____________________
III
Figure 10-15A is a PA radiograph of a middle-aged man.
1. The mediastinum is [normal/diffusely widened/focally
widened].
2. The trachea is _____________ and [narrowed/not
narrowed].
3. These findings suggest [tumor/infection] of the [anterior/
middle/posterior] mediastinum.
4. [The right hilum/The left hilum/Both hila] is/are big.
I
A. 2
B. 3
C. 4
D. 5
thyroid; thymus;
teratoma; thoracic
aorta; terrible
lymphoma
II
1. middle
2. anterior
3. anterior
4. middle
5. anterior
6. posterior
7. all three
8. anterior
9. middle
10. middle
III
1. focally widened
(right and left)
2. displaced; not
narrowed
3. tumor; middle
4. The right hilum
Figures 10-15B and 10-15C are axial and coronal images through the medi-
astinum and hilum. Note large nodes (N). This patient has lymphoma.
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174 Felson’s Principles of Chest Roentgenology
FIGURE 11-1 A
FIGURE 11-1 C
FIGURE 11-1 B
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175
ELEVEN
THE PLEURAL AND
EXTRAPLEURAL SPACES
The pleural cavity is a true space between the visceral and parietal pleura. The extrapleural
space, a potential space, lies between the rib cage and the adherent parietal pleura. Each
produces characteristic radiographic signs of disease, with the usual overlapping of signs.
1
The periphery of the base of each pleural cavity forms a deep
gutter around the dome of the corresponding hemidiaphragm.
This is called the costophrenic sulcus or angle. The deepest
and most caudal portion of the _____________ angle (sulcus) is
posterior. The lateral costophrenic sulcus is also fairly deep.
2
The [anterior/posterior/lateral] costophrenic angle is deepest
and seen only on the _____________ radiograph. It is not visible
on the PA radiograph because the dome of the diaphragm is
[above/below] it. On the PA view, fluid is best detected in the
_____________ costophrenic angles.
3
Romeo, shown in Figures 11-1A and 11-1B, slammed the back
door just as the husband fired. The bullet, almost spent, just
penetrated his chest wall and dropped harmlessly into the
pleural space. Figures 11-1A and 11-1B illustrate the depth of
the _____________ costophrenic angles and the hazards of sex.
(Editor’s note: Things were simpler in Dr. Felson’s time.)
1
costophrenic
2
posterior
lateral
above
lateral
3
posterior
In Figure 11-1A (upright film), the bullet in the posterior costophrenic angle
appears to lie in the abdomen. In Figure 11-1B (lateral film), the bullet is clearly
in the costophrenic angle. In Figure 11-1C (supine film), several days later, the
bullet has shifted in the pleural space.
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176 Felson’s Principles of Chest Roentgenology
FIGURE 11-2 A FIGURE 11-2 B FIGURE 11-2 C
FIGURE 11-3 A FIGURE 11-3 B FIGURE 11-3 C
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Eleven • The Pleural and Extrapleural Spaces 177
4
Free pleural fluid (e.g., blood, exudate, transudate) is heavier
thanthe air-filled lung and sinks to the base of the pleural 
cavity in the [upright/supine] position. It causes the normally
deep _____________ and _____________ costophrenic angles to
appear shallow or blunted. In Figure 11-2A, the lateral
costophrenic sulcus is normal. In Figure 11-2B, the lateral
costophrenic angle is _____________ because of a small effu-
sion. Additional fluid tracks up the pleural space, forming a
meniscus, as shown in Figure 11-2C. Figures 11-2A, 11-2B, and
11-2C are all the same patient.
5
On the lateral x-ray, the signs are exactly the same. In 
Figure 11-3A, both costophrenic angles are _____________. 
In Figure 11-3B, the left costophrenic sulcus is _____________. 
In Figure 11-3C, fluid forms a _____________, posteriorly.
6
In Figure 11-3C, only the [left/right] diaphragm is visible. 
Why? _____________.
4
upright;
posterior; lateral
shallow (blunt)
5
sharp (normal)
shallow (blunt)
meniscus
6
right
right contacts air in lung,
and left contacts pleural
fluid
Pleural fluid is often seen tracking up the major fissure on the lateral examina-
tion, a helpful secondary sign of pleural effusion (arrows on Figures 11-3B 
and 11-3C).
Clinical Pearl: The lateral film is more sensitive than the PA film for the
detection of small effusions. If there is a discrepancy between them, believe the
lateral. Figure 11-2 and Figure 11-3 are of the same patient. Compare each set 
of PA and lateral examinations.
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178 Felson’s Principles of Chest Roentgenology
FIGURE 11-4 A
FIGURE 11-4 B
FIGURE 11-4 C
FIGURE 11-4 D
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Eleven • The Pleural and Extrapleural Spaces 179
7
As you get older, gravity is less and less a friend. In radiology,
however, gravity can be a friend. What view would be most
helpful in proving that Figure 11-4A has a subpulmonic effusion?
_____________. The affected side should be [up/down] to display
the layered fluid.
8
Let’s review the signs of pleural effusion on the PA radiograph.
A small effusion _____________ the costophrenic angle. A larger
effusion forms a _____________ laterally, or hides in a
_____________ location. Remember, these are seen only in the
[upright/supine] position.
7
left lateral decubitus;
down
8
blunts (fills)
meniscus
subpulmonic
upright
In Figure 11-4A, the apparent elevation of the left hemidiaphragm is actually
subpulmonic fluid. The true diaphragm lies in normal position, but is obscured
by a parallel layer of free fluid. In the upright position, free fluid often collects
between the lung base and the top of the diaphragm. This “subpulmonic effusion”
makes the “diaphragm” appear elevated.
Figure 11-4B is a left lateral decubitus view of the patient shown in Figure 11-4A.
The free fluid has redistributed to the dependent side of the left pleural cavity,
between the lung and chest wall. Figure 11-4C, a CT scan, shows a gravity-
dependent pleural effusion layered posteriorly (E). In Figure 11-4D, ultrasound
shows a free subpulmonic effusion (E) (arrow = diaphragm.)
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180 Felson’s Principles of Chest Roentgenology
FIGURE 11-5
FIGURE 11-6 A
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Eleven • The Pleural and Extrapleural Spaces 181
9
We are now faced with the practical problem of recognizing
subpulmonic fluid because it so closely simulates an
_____________. On the left, the stomach bubble is normally
separated from the lung base by only the thin diaphragm.
Figure 11-5 shows the normal distance between the stomach
and the lung (arrow). In Figure 11-6A, with left subpulmonic
fluid, the gas bubble lies [farther from/closer to] the lung base.
This is known as the “stomach bubble sign.”
10
Compare Figures 11-5 and 11-6A.
A. In Figure 11-6A, the left costophrenic angle is
_____________, but a _____________ sign tells us there is
a left effusion.
B. What are the signs of pleural effusion on the right?
_____________.
9
elevated
hemidiaphragm
farther from
10
A. sharp; stomach
bubble
B. right costophrenic
angle blunt,
diaphragm changes
shape
FIGURE 11-6 B
There is no stomach bubble on the right. We often have to rely on the change of
shape of the right “diaphragm” to diagnose subpulmonic effusion. In Figure 11-5,
the apex of each diaphragm is in the mid clavicular line. With subpulmonic
effusion, often the apex of the “diaphragm” moves to a more lateral position or
changes shape, a helpful sign on either side.
In Figure 11-6B, the lateral x-ray shows blunting of both costophrenic angles 
posteriorly and a stomach bubble sign. There is also fluid in a major fissure
(arrow).
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182 Felson’s Principles of Chest Roentgenology
FIGURE 11-7
FIGURE 11-8 A FIGURE 11-8 B
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Eleven • The Pleural and Extrapleural Spaces 183
11
With a subpulmonic effusion:
1. The “diaphragm” appears _____________.
2. The apex of the “diaphragm” may shift [laterally/
medially].
3. The costophrenic angle may be shallow or show a
_____________.
4. The stomach may be _____________.
5. How would you confirm suspicions on the PA image?
_____________.
12
In the AP supine position, the fluid gravitates [anteriorly/
posteriorly] and causes the affected hemithorax to appear
[more/less] radiodense. The supine patient in Figure 11-7 has a
[left/right] pleural effusion. The supine view is [more/less]
sensitive than the erect view in detecting effusion.
13
When one hemithorax is totally opaque, is it usually due to con-
solidation and atelectasis, or is it due to a large _____________?
If the “white lung” is due to atelectasis, the mediastinum shifts
[toward/away from] the lesion. If the “white lung” is due to pleu-
ral fluid, it shifts [toward/away from] the lesion.
14
Compare the “white lungs” of Figures 11-8A and 11-8B.
A. Figure 11-8A is due to _____________. Why?
_____________.
B. Figure 11-8B is due to _____________. Why?
_____________.
15
Encapsulated (loculated) pleural effusion is attributable to
pleural adhesions, preexisting or developing after the appear-
ance of the fluid. It [does/does not] shift with changing
positions.
11
1. high, changes shape
2. laterally
3. meniscus
4. distant from lung
5. lateral or lateral
decubitus film
12
posteriorly
more
left; less (considerably)
13
pleural effusion
toward
away from
14
A. pleural effusion;
contralateral shift
B. atelectasis; ipsilat-
eral shift
15
does not
Clinical Pearl: Every student wants to know how much fluid one can see on a
radiograph. The erect PA requires greater than 175 mL; the erect lateral, 75 mL;
the decubitus, greater than 5 mL; the supine, more than several hundred
milliliters. Now you know. (Does the name Pavlov ring a bell?)
Clinical Pearl: If there is a “white hemithorax” but no shift, both atelectasis and
effusion may be present. There is a balance between collapse and pleural fluid,
or a tumor “anchors” the mediastinum, preventing a shift.
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184 Felson’s Principles of Chest Roentgenology
FIGURE 11-9 A
FIGURE 11-10 A
FIGURE 11-9 B
FIGURE 11-10 B
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Eleven • The Pleural and Extrapleural Spaces 185
16
Loculated fluid may simulate lung disease. See Figure 11-9A, 
an example of loculated pleural fluid. The borders of an encap-
sulation are generally [concave/convex] toward the lung. 
The margin forms an [obtuse/acute] angle with the chest 
wall when seen in profile (arrows). An air bronchogram is
[present/absent].
17
Occasionally, fluid accumulates in a fissure. It may look like 
a lung mass. Because it splits the fissure, this “pseudotumor” 
is often [lenticular/spherical] in shape.
18
Intrafissural effusion (“pseudotumor”) is bounded by visceral
pleura, and its margins appear [sharp/hazy] when seen in pro-
file (on edge). The encapsulated effusion in the minor fissure
should have sharp margins in [the PA/the lateral/both] view(s).
The margins of the “mass” in the major fissure should besharp
in [the PA/the lateral/both] views(s). (Remember, the beam
must be parallel to the fissure to see it.)
16
convex
obtuse
absent
17
lenticular
18
sharp
both
lateral
Figure 11-9B, a CT scan of the loculated fluid, shows a similar appearance
(arrows). There is a second smaller loculation as well. Compare this with the
free effusion of Figure 11-4C.
Figures 11-10A and 11-10B show the minor fissure “pseudotumor” (A) has sharp
margins in the PA and lateral. The two loculated collections in the major fissure
(B and C) are completely sharp only in the lateral projection. On the frontal
image, portions of the major fissure pseudotumors are indistinct.
Clinical Pearl: “Pseudotumors” are most commonly encountered in congestive
heart failure. As the congestive heart failure resolves, the loculated fluid
disappears (“vanishing tumor”).
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FIGURE 11-11 A
FIGURE 11-12 A
FIGURE 11-12 B
FIGURE 11-11 B
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Eleven • The Pleural and Extrapleural Spaces 187
19
Air in the pleural space is [more/less] radiolucent than the lung.
With a pneumothorax, the visceral pleura is seen as a thin white
line between air in the lung and air in the _____________. When
the lung is consolidated, the pneumothorax appears as a(n)
[line/edge] adjacent to the air in the pleural space.
20
In a supine patient, air collects [anteriorly/posteriorly] and
[inferiorly/superiorly]. In Figure 11-12A, we see what two signs
of pneumothorax? _____________ and _____________. Note the
subpulmonic air. Figure 11-12B shows air anterior to the lung
on a CT scan of a supine patient.
21
The supine film is [more/less] sensitive than the erect film for
detecting pneumothorax. If the patient cannot sit or stand, 
the _____________ position may be substituted. The side in
question should be [up/down].
19
more
pleural space
edge
20
anteriorly
inferiorly
hyperlucent pleural space
(no lung markings); vis-
ceral pleural line (arrows)
21
less
decubitus
up
Figure 11-11A shows the pleura on end between the pleural air and the aerated
lung (arrows). Figure 11-11B shows the pleural air against the edge of the
consolidated upper lobe (arrow). There are no lung markings in the air-filled
pleural space. There is also air in the subcutaneous tissues (arrowhead).
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188 Felson’s Principles of Chest Roentgenology
FIGURE 11-13
FIGURE 11-14 A
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Eleven • The Pleural and Extrapleural Spaces 189
22
Occasionally, air enters the pleural space with each breath but
cannot escape, increasing the intrapleural pressure. The increased
pressure [elevates/depresses] the diaphragm, collapses the
lung, and shifts the mediastinum [toward/away from] the
pneumothorax. This is known as a “tension pneumothorax.”
23
Tension pneumothorax compromises pulmonary venous return
and is a medical emergency. In Figure 11-13, we see the pleural
line and air in the pleural space, signs of pneumothorax. The
three radiographic signs that indicate a tension pneumothorax
are _____________, _____________, and _____________. The ribs
on that side may be further apart.
24
A hydropneumothorax is air and fluid in the pleural space. On
the erect film, the lower pleural space fills with _____________,
the upper pleural space fills with _____________, and an
_____________ is visible at their interface.
22
depresses (flattens)
away from
23
collapsed lung; depressed
diaphragm; shifted medi-
astinum
24
fluid
air
air-fluid level
FIGURE 11-14 B
Clinical Pearl: Rapid decompression of a tension pneumothorax can be
lifesaving. Learn the clinical signs so that you can diagnose and treat it without 
an x-ray. Signs include rapid onset of respiratory failure, decreased breath
sounds, deviated trachea, and jugular venous distention.
In Figures 11-14A and 11-14B, the left lung was removed for cancer. There is fluid
in the lower pleural space, air in the upper pleural space, and an air-fluid level.
The air bubble in the stomach is elevated, indicating diaphragmatic elevation
because the lung has been removed.
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190 Felson’s Principles of Chest Roentgenology
FIGURE 11-15
FIGURE 11-16 A
FIGURE 11-16 B
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Eleven • The Pleural and Extrapleural Spaces 191
25
The extrapleural space is a potential space that lies between
the rib cage and the pleural space. Lesions that arise in
structures within or bordering the extrapleural space (e.g., ribs,
muscle, connective tissue) may lift the adjacent [parietal/
visceral] pleura and push it toward the lung. A typical
extrapleural lesion is convex with a [sharp/hazy] interface with
the lung. It forms an [acute/obtuse] angle with the chest wall
when viewed in tangent.
26
A focal intrapleural lesion (encapsulated fluid) and an
extrapleural lesion can form [acute/obtuse] angles with the
chest wall and a [sharp/hazy] lung interface. The presence of a
rib lesion indicates a(n) [pleural/extrapleural] origin. If none is
visible, it may be difficult to separate the two.
27
Cross-sectional imaging helps separate extrapleural from
intrapleural lesions by eliminating overlap of structures. Figure
11-16A, a computed radiograph, shows a mass that forms an
[acute/obtuse] angle with the chest wall. The CT scan in Figure
11-16B shows that this mass is [intrapleural/extrapleural]. How
did you decide? _____________.
25
parietal
sharp
obtuse
26
obtuse
sharp
extrapleural
27
obtuse
extrapleural; expansile
irregular rib lesion, soft
tissue mass
Figure 11-15 illustrates an extrapleural lesion. The convex margin facing the
lung is sharp, and the borders are tapered (obtuse angle with chest wall). The
lesion looks similar to encapsulated fluid (see Figure 11-9A). The rib fractures
(arrowheads in Figure 11-15) indicate the extrapleural origin.
Clinical Pearl: Most extrapleural lesions are due to rib fractures (see Figure 11-15)
and rib metastasis (see Figure 11-16B).
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192 Felson’s Principles of Chest Roentgenology
FIGURE 11-17 A
FIGURE 11-17 B
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Eleven • The Pleural and Extrapleural Spaces 193
REVIEW
I
A. What are the three patterns seen with free pleural effusions
seen on an erect film?
(1) _____________.
(2) _____________.
(3) _____________.
B. List four clues to a subpulmonic effusion:
(1) _____________.
(2) _____________.
(3) _____________.
(4) _____________.
II
To diagnose a pneumothorax, one must see:
(1) _____________.
(2) _____________.
III
Figures 11-17A and 11-17B are supine x-rays of a young woman
who was in an auto accident.
A. On the left, there is [increased/decreased] radiodensity,
which is most likely due to _____________.
B. On the right, there is [increased/decreased] radiolu-
cency, which is due to _____________.
C. The mediastinum is [normal/focally widened/generally
widened], which is most likely due to _____________.
D. Her choice of jewelry indicates _____________.
I
A.
(1) blunt costophrenic
angle
(2) meniscus
(3) subpulmonic
effusion
B.
(1) high “diaphragm”
(2) stomach bubble
sign
(3) “diaphragm” apex
shifts, changes
shape
(4) shallow
costophrenic angle
or thickened fissure
II
(1) peripheral
hyperlucency
(intrapleural air)
(2) visceral pleural line
or edge
III
A. increased; layered
pleural fluid (blood)
B. increased;
pneumothorax
(see visceral pleural
line)
C. generally widened;
hemorrhage
D. . . . . . .
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194 Felson’s Principles of Chest Roentgenology
FIGURE 12-1 A
FIGURE 12-1 B
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195
TWELVE
CARDIOVASCULAR
DISEASE
To analyze cardiovascular disease fully, the heart, pulmonary vessels, lungs, and pleural
space all must be studied. Every beginner should be able to recognize the cardiovascular
structures, cardiomegaly, and left heart failure. If you can, you will be ahead of most of 
your peers.
1
Figure 12-1A is an x-ray of theheart and great vessels. On the
left side, there are four bulges (moguls to you skiers). They are:
1. _____________.
2. _____________.
3. left atrial appendage.
4. _____________.
2
The right heart border is formed by the right atrium (5).
The right ventricle does not form a lateral border on the frontal
view. Above the right heart border is the _____________ (6).
Above the ascending aorta, the _____________ (7) is parallel to
the upper mediastinum.
3
On the lateral film, the right heart is anterior, and the left heart
is posterior. Label the cardiovascular structures on the lateral
(Figure 12-1B).
1. _____________.
3. _____________.
4. _____________.
6. _____________.
8. _____________.
9. _____________.
1
1. aortic arch
2. main pulmonary
artery
4. left ventricle
2
ascending aorta
superior vena cava
3
1. aortic arch
3. left atrium
4. left ventricle
6. ascending aorta
8. right ventricle
9. descending aorta
(proximal)
Two medical students spotted a bear while walking in the woods. Student #1
took out sneakers from his backpack and put them on. “You can’t outrun 
a bear,” said Student #2. Said Student #1, “I don’t have to, I just have to 
outrun you.”
Note: The normal left atrial appendage is concave, not convex.
Note: In reality, the right heart is anterior and the left heart is posterior—not left
and right.
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196 Felson’s Principles of Chest Roentgenology
FIGURE 12-2
FIGURE 12-3 A
FIGURE 12-3 B
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Twelve • Cardiovascular Disease 197
4
Sometimes the terminology is confusing. Review the following:
A. The left heart sits [anterior/posterior] to the right heart.
B. On the frontal view, the normal right heart border is
formed by the _____________ only.
C. On the frontal view, the left atrial appendage is normally
[concave/convex].
5
In Figure 12-2, the cardiothoracic ratio is _____________. The
upper limit of normal is _____________. These measurements
are unreliable on an AP image because of _____________.
6
The “heart” may be enlarged because of intrinsic cardiac disease
or appear enlarged by surrounding pericardial fluid. The x-ray
does not distinguish between cardiac _____________ and pericar-
dial _____________. For this reason, many prefer the term
“cardiac silhouette” to “heart size.”
7
If the left atrium enlarges, it protrudes [laterally/medially] 
and [anteriorly/posteriorly]. On the frontal view, its margin
becomes [concave/convex].
4
A. posterior
B. right atrium
C. concave
5
0.43 (12/28)
0.50
cardiac magnification
6
enlargement
fluid
7
laterally
posteriorly
convex (mogul 3)
Determining cardiac enlargement is easy. Measure the horizontal width of the
heart and divide it by the widest internal diameter of the thorax. The normal
cardiothoracic ratio is less than 0.5. (Oversimplified, but useful.)
Clinical Pearl: The cardiothoracic ratio is based on population standards. 
For a given patient, an increase of greater than 1 cm in cardiac diameter from 
a prior film is a more reliable index of cardiac enlargement than the cardiotho-
racic ratio. In general, a radiologist with a ruler is a radiologist in trouble,
but these measurements work fairly well on erect, inspiratory PA radiographs.
Figures 12-3A and 12-3B show an enlarged left atrium. The upper left heart
border bulges laterally (arrow on Figure 12-3A) and posteriorly (arrow on 
Figure 12-3B). Compare with Figures 12-1A and 12-1B.
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198 Felson’s Principles of Chest Roentgenology
FIGURE 12-4 A
FIGURE 12-5 A
FIGURE 12-4 B
FIGURE 12-5 B
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Twelve • Cardiovascular Disease 199
8
In Figures 12-4A and 12-4B, the white arrow points to 
the _____________. The black arrowhead points to the
_____________, and the white arrowhead points to the
_____________. The aorta is so tortuous that even the aortic
arch is visible.
9
To review: A large left atrium bulges _____________ on the PA
film and _____________ on the lateral film. A large left ventricle
bulges _____________ on the PA and _____________ on the lat-
eral x-rays.
8
left ventricle
descending aorta
ascending aorta
9
laterally
posteriorly
laterally and inferiorly
posteriorly and inferiorly
With left ventricular enlargement on the frontal view, the left heart border
moves laterally, and the cardiac apex moves inferolaterally. On the lateral view,
the left heart border moves inferoposteriorly.
Detecting right heart enlargement is more difficult. In the frontal projection, the
normal right heart protrudes slightly to the right of the spine, and an enlarged
heart protrudes further to the right (soft science, at best). In the lateral projec-
tion, the right heart enlarges anteriorly and superiorly. The normal right heart
contacts the lower one third of the sternum, whereas the enlarged right heart
contacts the lower one half. Compare the enlarged right heart (Figures12-5A and
12-5B) with the enlarged left heart in Figures12-4A and 12-4B.
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200 Felson’s Principles of Chest Roentgenology
FIGURE 12-6 A
FIGURE 12-7 A FIGURE 12-7 B
FIGURE 12-6 B
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Twelve • Cardiovascular Disease 201
10
Many heart diseases also alter the pulmonary vessels. In a
normal erect patient, gravity causes most blood to flow to the
[apex/base]. In Figure 12-6A, the upper lobe vessels are
[larger/smaller] than the lower lobe vessels at approximately
the same distance from the hilum. In a supine patient, what
happens to blood flow? _____________.
11
In Figure 12-6B, the upper lobe vessels are [larger/smaller] than
the lower lobe vessels. This is called cephalization or vascular
redistribution. Cephalization, not heart size, is the key to
diagnosing elevated left heart pressure. Compare Figure 12-6A
and Figure 12-6B until cephalization is absolutely clear.
12
Look at Figures 12-7A and 12-7B. Which patient has prominent
upper lobe vessels as a result of an atrial septal defect?
_____________.
10
base
smaller
apex = base, evens out
11
larger
12
Figure 12-7A
Clinical Pearl: Left heart failure and mitral valve stenosis are the most frequent
causes of redistribution or cephalization. A shunt (e.g., atrial or ventricular
septal defect) causes all vessels to enlarge.
The patient in Figure 12-6B is in left heart failure. There is enlargement of the
upper lobe vessels (cephalization). This is mild left heart failure because the
vessel margins remain distinct (i.e., no edema).
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202 Felson’s Principles of Chest Roentgenology
FIGURE 12-8 A
FIGURE 12-8 B
FIGURE 12-8 C FIGURE 12-9
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Twelve • Cardiovascular Disease 203
13
As the left atrial pressure increases, interstitial edema develops.
The edema causes the vessel margins to become [sharper/less
sharp] and the peripheral interstitial markings to become
[more/less] prominent. Figure 12-8A shows mild left heart failure.
The upper and lower lobe vessels are equal, and there is no
edema.
14
In Figure 12-9, there is evidence of severe edema. The edema
tends to be more severe in the gravity-dependent [upper/
lower] lungs. With alveolar edema, the pulmonary vessels may
not be visible. Why? _____________.
15
In left heart failure, the cardiac silhouette often enlarges. In
addition:
A. In mild failure, there is _____________ of the vessels but
no edema.
B. Moderate failure causes indistinct vessel margins as a
result of [alveolar/interstitial] edema. _____________
lines and pleural effusions may be present.
C. Severe failure causes [alveolar/interstitial] edema and
pleural effusions.
13
less sharp
more
14
lower
water density lung
around water density
vessels
15
A. cephalization
B. interstitial; Kerley B
C. alveolar
Figure 12-8B shows moderate heart failure in the same patient as in Figure 12-8A
with large but hazy upper lobe vessels and prominent interstitium. Fluid thick-
ens the interlobular septa, causing short linesperpendicular to the pleural
surface. These are “Kerley B” lines indicating interstitial edema (arrows). 
Figure 12-8C is a close-up of Kerley B lines (arrows) in a different patient.
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204 Felson’s Principles of Chest Roentgenology
FIGURE 12-10
FIGURE 12-11
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Twelve • Cardiovascular Disease 205
16
Let us go back to Kerley lines. Kerley B lines indicate fluid in 
the _____________. Kerley also described A and C lines. He was
obviously a splitter, rather than a lumper. We will not worry
about A and C lines. Figure 12-10 is a CT scan of Kerley B lines
(arrows).
17
Figure 12-11 is a portable radiograph.
1. It is taken [supine/erect].
2. The cardiothoracic ratio is _____________.
3. The upper lobe pulmonary vessels are _____________.
4. Patient [is/is not/can’t tell] in heart failure.
18
Name the physiologist whose law described the relationship
between edema, hydrostatic pressure, and oncotic pressure:
_____________. Figure 12-12 is a _____________.
16
interlobular septa
17
1. supine (arrow
points down)
2. not valid
(magnification)
3. prominent, but this
is normal in a
supine patient
4. can’t tell
18
Starling; Starling resistor
FIGURE 12-12
Clinical Pearl: With cephalization alone, lung auscultation is usually normal.
With interstitial edema, crackling rales are audible. With alveolar edema, rales
are audible.
Determining cardiomegaly and cephalization is unreliable on supine films.
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206 Felson’s Principles of Chest Roentgenology
FIGURE 12-13
FIGURE 12-14
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Twelve • Cardiovascular Disease 207
19
Figure 12-13 is a PA radiograph:
A. Cardiothoracic ratio is _____________.
B. Is there cephalization? _____________.
C. Is there edema? _____________.
D. Is there a pleural effusion? _____________.
E. There are no significant signs of left heart failure.
Perhaps the large cardiac silhouette is due to a
_____________.
19
A. greater than 50%,
high
B. no
C. no
D. no
E. pericardial effusion
FIGURE 12-15
Figure 12-14, an echocardiogram, shows a large pericardial effusion (P). Figure 12-15,
a CT scan of a different patient, shows a pericardial effusion (P), bilateral pleu-
ral effusions, and left lower lobe consolidation (atelectasis). Echocardiography,
CT, and MRI accurately depict pericardial effusions, but echocardiology is most
cost-effective.
Clinical Pearl: Marked generalized enlargement of the cardiac silhouette, 
with no or mild signs of left heart failure, is most likely due to pericardial
effusion. Cardiomyopathy and multivalvular heart disease may have a similar
radiographic presentation.
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208 Felson’s Principles of Chest Roentgenology
FIGURE 12-16 FIGURE 12-17
FIGURE 12-18
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Twelve • Cardiovascular Disease 209
BONUS SECTION
Patients with heart or lung disease often wind up in the 
ICU with many support tubes and catheters. These should be
evaluated on every x-ray before your standard search.
20
In Figure 12-16, the apparatus is correctly positioned. (L =
electrocardiogram lead on skin.)
A. Endotracheal tube (E) with its tip [at the carina/in the
mid trachea/in the cervical trachea].
B. Central venous catheter (C) is in the _____________.
C. Nasogastric tube tip (N) is in the _____________.
21
In Figure 12-17 (arrowheads):
A. The endotracheal tube is in the _____________.
B. The central venous pressure catheter is in the
_____________.
22
Figure 12-18 (L = electrocardiogram lead): X-ray request: “Check
nasogastric tube position.” The tube is _____________.
20
A. in the mid trachea
B. superior vena cava
C. stomach
21
A. right main bronchus
B. superior vena cava
22
coiled in a hiatal hernia
Congratulations!
You are done. (“He who laughs, lasts!”—Leo Rosten). There is no review quiz.
Take a break! When you come back, challenge yourself to the dozen great quiz
cases in the last section. Also, be sure to read Felson’s “Ten Axioms for a
Lifetime of Learning in Medicine” (next page). The CD on the back cover is worth
a look.
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210 Felson’s Principles of Chest Roentgenology
Felson’s 10 Axioms for a 
Lifetime of Learning in Medicine
1. If you like it, you’ll learn it; so learn to like it.
2. Principles are as important as facts. If you master the principles, you can make
up the facts.
3. You learn better when you know your goals. If you don’t now where you’re
going, says the Talmud, all roads will take you there. But if you do know, you’ll
get there much quicker.
4. Follow your cases. I’ve learned and remembered more by follow-up than any
other way. It’s hard work, but as Confucius say, “He learneth most who worketh
most.” Or was it Knute Rockne?
5. Like sex, learning is better if you are actively involved. When you read, talk back
to the author. Be skeptical. Don’t follow the authorities too closely or you may
become a Brown Nose Duck; he can fly as fast as the leader, but can’t stop as
quick.
6. Reinforcement is essential for acquiring knowledge. But don’t reinforce by
simple repetition; use some other method than the original way you learned it.
See a case, look it up; read an article, find a case or ask a question.
7. Reward is important for learning. Show off what you know. Brag a little. Speak
up in class. Tell your spouse or sweetheart; tell your colleagues; don’t bother to
tell your friends—you won’t have any.
8. Different people learn best by different methods. Figure out your own best method
and cater to it, whether it be reading, listening, observing, or doing, or a combina-
tion of these. Don’t depend on great teachers. They are as rare as great students.
9. Quick retrieval of once-acquired information is crucial. The home computer is
ideal but other good retrieval methods are available. Create your own personal
modification and keep improving it. Without a recall system you’re a “loser,” an
old man with a stuck zipper.
10. Divide your study time into prime time, work time, and sleepy time. Biorhythms
vary widely among students, so develop your own study schedule. Don’t watch
television during prime time and don’t read medicine during sleepy time.
Felson, B. Humor in Medicine, 1989; RHA Inc., Cincinnati, Ohio.
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211
QUIZ
A DOZEN GREAT
CASES
CHALLENGE Each case tests your ability to apply the fundamental principles
we have just gone over and over.
SUGGESTIONS 1. Read the history.
2. Evaluate the x-ray with your routine scanning pattern
(ATMLL), making all the pertinent observations.
3. Then, and only then, answer all questions before you turn to
the answers on the next page.
Beware of “satisfaction of search.” There is a tendency when reading x-rays 
to be so thrilled that you have actually found an abnormality that you then
relax your search. Don’t! Many patients have several abnormalities that you can
combine to arrive at a diagnosis.
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Quiz • A Dozen Great Cases 213
Case 1
History: This is a young man with cancer (Figure Q-1).
Metal nipple markers have been placed to distinguish nipples, which sometimes show on 
x-rays, from real pulmonary nodules.
1. Is the lung abnormal? _____________ If so, where? _____________ What? ____________
2. Are there any changes to suggest pleural effusion? [yes/no]
3. What type of surgery did the patient have? ____________ (Hint: Is anything missing?)
4. Diagnosis: Can you combine the history and x-ray findings to suggest a diagnosis?
_____________
FIGURE Q-1
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214 Felson’s Principles of Chest Roentgenology
Case 1
1. Yes, below the right nipple marker, where the ribs cross, there is a pulmonary
nodule.
2. No. The costophrenic angles are sharp. The stomach bubble sign is absent.
Diaphragms are normally shaped.
3. The right shoulder has been amputated. A systematicapproach helps avoid
embarrassing misses.
4. Diagnosis: Patient had a shoulder amputation, most likely for cancer. The nodule is
most likely a pulmonary metastasis. The amputation was for osteosarcoma.
“Intuition is the source of scientific knowledge.”—Aristotle
“Aristotle could have avoided the mistake of thinking that women have fewer
teeth than men by the simple device of asking Mrs. Aristotle to open her
mouth.”—Bertrand Russell
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Case 2
History: This is a 30-year-old epileptic with high fever and chills for 5 days (Figures Q-2A
and Q-2B).
1. There is an abnormality in the _____________ lobe.
2. Describe the lesion in detail. _____________
3. The arrow points to a(n) _____________.
4. Diagnosis: Put the x-ray findings and history together for a logical diagnosis.
_____________
FIGURE Q-2 A FIGURE Q-2 B
Quiz • A Dozen Great Cases 215
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216 Felson’s Principles of Chest Roentgenology
Case 2
1. right upper lobe (it sits on the major fissure and above the minor fissure)
2. There is a mass or focal alveolar consolidation with a central cavity, air-fluid level.
3. air-fluid level
4. Diagnosis: This is a lung abscess in an epileptic who probably aspirated during
a seizure. Tuberculosis, another reasonable possibility, is usually more indolent.
Aspiration most often involves the gravity-dependent portions of the lung in a supine
patient (posterior segments of the upper lobes and the superior and posterior basal
segments of the lower lobes).
“It’s what you learn after you know it all that counts.”—Earl Weaver
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Case 3
History: This hypotensive patient has a gunshot wound to the left chest (Figure Q-3).
Identical paper clips mark the entrance and exit wounds.
1. This radiograph is most likely [erect/supine] (PA/AP).
2. Describe the major radiologic findings of the left hemithorax. _____________
3. The mediastinum is [shifted right/shifted left/not shifted].
4. Are proximal air bronchograms visible? _____________ What does this tell you?
_____________
5. The police tell us that he was shot from the front. Is the entry wound midline or 
left-sided? (Remember, they are identical paper clips.) _____________
6. Diagnosis: _____________
FIGURE Q-3
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218 Felson’s Principles of Chest Roentgenology
Case 3
1. supine (AP)—patient is hypotensive
2. The left hemithorax is opaque laterally. The partially aerated lung is visible medially.
3. shifted right (contralateral side)
4. Yes. The air bronchogram on the left tells us that the major airways are open. 
There is no central endobronchial obstruction, and the surrounding lung is almost
airless (water density).
5. Left-sided. This is an AP supine film, so the anterior clip would be magnified. Because
identical paper clips were used, the bullet must have entered the left chest (magnified
clip) and exited in the midline.
6. Diagnosis: Left hemothorax from gunshot wound. Relaxation atelectasis. Increased
pressure in left hemithorax causing contralateral mediastinal shift.
“Why shouldn’t truth be stranger than fiction? Fiction has to be believable.”—
Mark Twain
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Case 4
History: This middle-aged man was admitted to the ICU with fever, chills, and a white blood
cell count of 19,000/mm3.
Figure Q-4A was obtained shortly after admission. There is a drain in the right pleural space
laterally.
1. A indicates a _____________ catheter in [satisfactory/unsatisfactory] position.
2. B indicates an _____________ tube in [satisfactory/unsatisfactory] position.
3. Describe the lung abnormalities. _____________
4. Diagnosis: _____________
5. Several hours later, he became more short of breath. Figure Q-4B shows what
additional finding? _____________
FIGURE Q-4 A FIGURE Q-4 B
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220 Felson’s Principles of Chest Roentgenology
Case 4
1. central venous pressure catheter; satisfactory
2. endotracheal tube; unsatisfactory (too high)
3. Bilateral dense consolidation, air bronchograms, silhouette signs of diaphragms,
blunt right costophrenic angle.
4. Diagnosis: Pneumonia.
5. Tension pneumothorax on right—air in pleural space, low right diaphragm, heart
shifted to the left.
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Case 5
History: This is a 50-year-old woman with pain on inspiration.
Figure Q-5A is a baseline image obtained 10 months earlier. Figure Q-5B is the current
image.
1. In Figure Q-5A, the [right/left] lung is more radiolucent. Explain the discrepancy.
_____________
2. Ten months later, there have been striking changes (Figure Q-5B). The cardiac 
size (cardiac silhouette) is _____________, whereas the pulmonary vessels [show
cephalization/are normal]. [The right/The left/Both] costophrenic angle(s) is(are)
blunted.
3. Diagnosis: Combining the history and your radiographic observations, the current
image shows _____________ and _____________, most likely caused by _____________.
FIGURE Q-5 A
FIGURE Q-5 B
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222 Felson’s Principles of Chest Roentgenology
Case 5
1. The left lung is more lucent. There has been a left mastectomy. The breast is miss-
ing, and there are clips in the axilla. There is less soft tissue on the left, so there is
less absorption of radiation.
2. enlarged; are normal. The right costophrenic angle is blunt and there is a small
meniscus. The right diaphragm also has changed shape (subpulmonic effusion).
3. Diagnosis: Pericardial effusion and right pleural effusion caused by metastatic breast
cancer.
“I like only two kinds of men: domestic and imported.”—Mae West
“She may be good for nothing, but she’s not bad for nothing.”—Mae West
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Case 6
History: This is a young man without symptoms (Figures Q-6A and Q-6B).
1. There is a strange cardiomediastinal shape on the [right/left]. It causes a silhouette
sign of what three cardiovascular structures? _____________, _____________, and
_____________
2. Is there an abnormality visible on the lateral film? _____________
3. Allowing for some overlap, there is a mass predominantly in the [anterior/middle/
posterior] mediastinal compartment.
4. Diagnosis: Formulate a differential diagnosis. _____________
FIGURE Q-6 A
FIGURE Q-6 B
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224 Felson’s Principles of Chest Roentgenology
Case 6
1. left. left atrium, pulmonary artery, and aortic arch (knob) (left upper mediastinum).
2. Density in retrosternal clear space, between sternum and trachea.
3. anterior and middle. This is a large anterior and middle mediastinal mass on the left.
The lateral radiograph shows the mass predominantly in the anterior mediastinum.
The silhouette sign indicates anterior mediastinum (left atrium) and middle medi-
astinum (pulmonary artery, aortic knob).
4. Diagnosis: Remember the “5 T’s”:
Thyroid. This mass is too low.
Thoracic aortic aneurysm. The ascending thoracic aorta is on the right and looks normal
(i.e., not aortic aneurysm).
Terrible lymphoma. This is usually lobulated and bilateral.
Thymoma and Teratoma are the best choices. (Large masses commonly cross mediastinal
boundaries.) This was a thymoma.
“If law school is so hard to get through, how come there are so many
lawyers?”—Calvin Trillin
“Health food makes me sick.”—Calvin Trillin
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Case 7
History: These are two older women, both with a cough (Figures Q-7A and Q-7B).
1. Both women have [interstitial/alveolar] consolidation of the _____________ lobe.
2. What forms the sharp lower edges of their lesions? _____________ Reason for sharp
edge? _____________
3. Patient [A/B] has a right hilar mass as well.
4. Patient [A/B] has a right pleural effusion.
5. Patient [A/B] has consolidation as a result of a central obstruction.How did you
know? _____________
6. Diagnosis: Patient [A/B] has a lung cancer.
FIGURE Q-7 A FIGURE Q-7 B
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226 Felson’s Principles of Chest Roentgenology
Case 7
1. alveolar consolidation—right upper lobe
2. The minor fissure is the sharp lower border. The upper lobe is consolidated, and the
middle lobe is well aerated.
3. A
4. A
5. A. There is no air bronchogram.
6. Diagnosis: Patient A has a carcinoma obstructing the right upper lobe bronchus 
(i.e., no right upper lobe air bronchogram) and a hilar mass and effusion. Patient B
has alveolar infiltrate or airspace consolidation with patent airways as a result of a
community-acquired pneumonia.
“An onion can make people cry but there’s never been a vegetable that can make
people laugh.”—Will Rogers
“We are all here for a spell; get all the good laughs you can.”—Will Rogers
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Case 8
History: This is a 60-year-old patient with increasing shortness of breath over several days
(Figures Q-8A and Q-8B). His file contains an x-ray done 6 months earlier, when he was
asymptomatic (Figure Q-8C).
1. What has happened to the heart size in the 6-month interval? _____________
2. What has happened to the pulmonary vessels? _____________
3. How do the costophrenic angles compare? _____________
4. What accounts for the right mid lung densities? _____________
5. Diagnosis: _____________
FIGURE Q-8 A
FIGURE Q-8 C
FIGURE Q-8 B
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228 Felson’s Principles of Chest Roentgenology
Case 8
1. The heart is bigger.
2. The pulmonary vessels are bigger and slightly less sharp as a result of interstitial
edema.
3. There is fluid in the right costophrenic angle.
4. Fluid trapped in the major and minor fissures (pseudotumors). Figure Q-8B shows
the markedly thickened fissures.
5. Diagnosis: The patient is in left heart failure (congestive heart failure).
“One day my father took me aside and left me there.”—John Vernor
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Case 9
History: This is an older man with shortness of breath. Figures Q-9A and Q-9B are admis-
sion x-rays.
1. What is the diagnosis on admission? _____________
2. Two days later, the patient developed increasing dyspnea. In Figure Q-9C, how have
the lungs changed? _____________
3. Diagnosis: _____________
FIGURE Q-9 A
FIGURE Q-9 C
FIGURE Q-9 B
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230 Felson’s Principles of Chest Roentgenology
Case 9
1. Emphysema (chronic obstructive pulmonary disease). Hyperinflated, sparse upper
lobe markings.
2. Left diaphragm silhouette sign, dense retrocardiac area, elevated left diaphragm
(compare position of stomach bubble).
3. Diagnosis: Left lower lobe consolidation—most likely atelectasis. Pneumonia probably
would take longer to develop.
“He’s crazy; he thinks he’s a chicken.” “Why don’t you take him to a psychia-
trist?” “I can’t, we need the eggs.”—Woody Allen
“Schizophrenia beats dining alone.”—Oscar Levant
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Case 10
History: This is an older man with cough for 4 months.
1. In Figure Q-10A, there is an abnormality in or over the [right hilum/left hilum/
anterior mediastinum].
2. In Figure Q-10B, this abnormality is seen _____________.
3. Figures Q-10A and Q-10B show diaphragms are _____________. This indicates
_____________.
4. Diagnosis: _____________
FIGURE Q-10 A
FIGURE Q-10 B
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232 Felson’s Principles of Chest Roentgenology
Case 10
1. right hilum
2. superimposed on the descending aorta. It is in the right lower lobe.
3. low and flat. This indicates hyperinflation, probably chronic obstructive pulmonary
disease
4. Diagnosis: Right lower lobe mass, probably cancer in a smoker
CT shows the mass adjacent to the right hilum
“If you do nothing, how do you know when you are finished?”—Anonymous
FIGURE Q-10 C
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FIGURE Q-11 A
FIGURE Q-11 B
Quiz • A Dozen Great Cases 233
Case 11
History: This is an older man from the cardiology clinic, complaining of dyspnea for days
and the sudden onset of chest discomfort and fever (Figures Q-11A and Q-11B).
1. The cardiac silhouette is _____________.
2. The pulmonary vessels are _____________.
3. Diagnosis: What is his cardiac diagnosis most likely? _____________
4. Diagnosis: What explains his acute symptoms? _____________
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234 Felson’s Principles of Chest Roentgenology
Case 11
1. large
2. enlarged (cephalization) and mildly indistinct
3. Diagnosis: mild left ventricular failure explains dyspnea for days.
4. Diagnosis: Free air under the diaphragm (from perforated ulcer) explains sudden
chest discomfort and fever.
“There is nothing wrong with sobriety in moderation.”—John Ciardi
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Case 12
History: The patient was described as follows (Figure Q-12): “Swimming lopsided and looks ill.”
1. The _____________ lung is consolidated.
2. This is an [alveolar/interstitial] pattern.
3. The patient swam _____________ side down because _____________.
4. The patient is a _____________.
FIGURE Q-12
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236 Felson’s Principles of Chest Roentgenology
Case 12
1. left (compare with normally aerated right lung)
2. alveolar (the left lung is airless [water density])
3. left side down because the left lung is heavier than the right lung
4. Trachemys scripta—terrapin (turtle)
Dr. Timothy T. Klostermeier of Wilmington, Ohio, nursed the sick turtle back to
health with daily subcutaneous shots of tetracycline for 2 weeks. (Radiology
1996;199:58; with permission.)
This case validates the “purple cow” theory of education. If you understand
“purple,” and you understand “cow,” you will recognize a purple cow the first
time you see one.
“It’s not over ‘til it’s over.”—Lawrence A. Berra (Yogi Berra)
“It’s over!”—Lawrence R. Goodman, M.D.
You are done! For those looking for more unknown cases, board review cases,
and a few other goodies, there is a CD in the back cover.
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INDEX
A
Abdomen
gas-containing structures of, 38f, 39, 40f, 41
on computed tomography, 62f, 63
search pattern for, 40f, 41
Abscess, pulmonary, 215f, 216
Accessory fissures, 80f, 81, 82f, 83
Acini, 50f, 51, 134f, 135. See also Alveoli
Acute alveolar disease. See Alveolar filling disease
Adenopathy
hilar, 170f, 171, 172f, 173
mediastinal, 164f, 165
Adhesive atelectasis, 131
Air
in lung, 19, 20f, 21, 66f, 67, 86f, 87. See also Air
bronchogram sign
pleural. See Pneumothorax
subcutaneous, 186f, 187
subpulmonic, 186f, 187
under diaphragm, 54f, 55
Air bronchogram sign, 102–115
absence of, 110f, 111, 113, 114f, 115
definition of, 105, 106f, 107, 109
in alveolar filling disease, 108f, 109, 143
in left lower lobe collapse, 122f, 123
in left lower lobe pneumonia, 106f, 107
interpretation of, 112f, 113
model analogue of, 106f, 107
on computed tomography, 106f, 107
through cardiac shadow, 110f, 111
vs. silhouette sign, 106f, 107. See also
Silhouette sign
Air trapping, expiratory film for, 14f, 15
Air-fluid level, 148f, 149
after lung removal, 188f, 189
in hydropneumothorax, 188f, 189
in pneumonia, 148f, 149
Alveolar edema, 202f, 203
Alveolar filling disease, 50f, 51, 52f, 53, 136f, 137, 138f,
139
acute, 145
diffuse interstitial disease and, 144f, 145
focal, 146f, 147
lobar sites of. See Consolidation
multifocal, 144f, 145
on computed tomography, 6f, 67, 136f, 137
signs of, 142f, 143, 145, 153
Alveoli, 50f, 51, 52f, 53, 134f, 135
air in, 66f, 67, 137
edema of, 202f, 203
filling of, 136f, 137. See also Alveolar filling 
disease
Aneurysm, aortic arch, 166f, 167
Anterior mediastinum, 160f, 161, 173. See also
Mediastinum
mass of, 162f, 163
Anteroposterior (AP) view, 2f, 3, 16f, 17
Aorta
ascending
in left heart enlargement,198f, 199
in mediastinal search, 45, 45f
in right upper lobe consolidation, 96f, 97
on computed tomography, 58f, 59, 91, 91f, 
156f, 157
on lateral x-ray, 38f, 39, 90f, 91, 154f, 155, 
194f, 195
on normal x-ray, 36f, 37, 154f, 155
descending
in left heart enlargement, 198f, 199
in left lower lobe consolidation, 95
in mediastinal search, 45, 45f
mediastinal location of, 166f, 167, 167f
on computed tomography, 58f, 59, 91, 91f, 
156f, 157
on lateral x-ray, 90f, 91, 154f, 155, 194f, 195
on normal x-ray, 154f, 155
post-traumatic pseudoaneurysm of, 170f, 171
three-dimensional view of, 28f, 29
Aortic knob (arch)
aneurysm of, 166f, 167
in mediastinal search, 45, 45f
on computed tomography, 26f, 27, 58f, 59, 90f, 91,
156f, 157
on lateral x-ray, 38f, 39, 154f, 155, 194f, 195
on normal x-ray, 36f, 37, 38f, 39
Apical lordotic position, 17
Artifacts, 4f, 5
Ascending aorta. See Aorta, ascending
Aspiration, of abscess, 215f, 216
of pin, 84f, 85, 85f
Atelectasis, 113, 229f, 230. See also Collapse
adhesive, 131
bandlike, 130f, 131
cicatricial, 130f, 131
hypoventilation, 130f, 131
mechanisms of, 131
mediastinal shift and, 182f, 183
obstructive
central, 126f, 127, 129, 129f, 131
peripheral, 127
passive (relaxation), 129, 129f
postoperative, 128f, 129
resorptive, 127
structure shift in, 124f, 125, 182f, 183
Atrial septal defect, 200f, 201
Atrium. See also Heart
left, 194f, 195, 199
enlargement of, 196f, 197
right, 194f, 195
Axial plane, 64f, 65, 68f, 69
Azygos fissure, 80f, 81, 84f, 85
Azygos lobe, 80f, 81
Note: Page numbers followed by f refer to figures.
237
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238 Index
B
Barium swallow, 166f, 167
Bleeding, mediastinal, 158f, 159, 170f, 171, 192f, 193
Bone, 19
density of, 27, 87
on computed tomography, 56f, 57, 62f, 63
Breast, 42f, 43
postmastectomy absence of, 54f, 55
Bronchiectasis, 104f, 105, 105f, 112f, 113
Bronchus (bronchi). See also specific lobes
air-filled. See Air bronchogram sign
contrast-aided examination of, 103, 104f, 105
dilation of, 104f, 105, 105f, 112f, 113
focal air trapping in, 14f, 15
obstruction of, 126f, 127, 128f, 129. 
See also Collapse
on computed tomography, 60f, 61, 102f, 103
right main stem, 60f, 61
tumor of, 110f, 111
Bronchus intermedius, 121, 121f
Bullae, 150f, 151
Bullet, in pleural space, 174f, 175
C
Calcification
aortic arch, 166f, 167
in granulomatous infection, 148f, 149
on oblique view, 6f, 7
Cancer
lung. See Lung cancer
metastatic, 190f, 191, 213f, 214
Cardiac cycle, magnetic resonance imaging of, 30f, 31
Cardiac shadow, air bronchogram through, 110f, 111
Cardiac silhouette, 197. See also Heart
Cardiothoracic ratio, 196f, 197
Cardiovascular disease, 194–209. See also Heart
Carina, 36f, 37, 38f, 39, 45, 45f
on computed tomography, 64f, 65
Catheter, 4f, 5, 208f, 209
Cavitary mass, 146f, 147, 148f, 149
Central venous catheter, 4f, 5, 208f, 209
Cephalization, 200f, 201
Chronic obstructive pulmonary disease (COPD), 20f,
21, 150f, 151, 152f, 153. See also Emphysema
Clavicle, 42f, 43
Collapse, 116–134
air bronchogram and, 122f, 123
bronchial obstruction and, 126f, 127, 128f, 129
fibrosis and, 130f, 131
hilar displacement and, 124f, 125
hydrothorax and, 129, 129f
left lower lobe, 116f, 117, 122f, 123, 124f, 125, 128f, 129
left lung, 116f, 117
left upper lobe, 116f, 117, 120f, 121, 132f, 133
lingula, 119, 120f, 121, 132f, 133
mechanisms of, 126f, 127
moving marker structures and, 122f, 123
postoperative, 129, 129f, 132f, 133
right lower lobe, 116f, 117, 119, 119f, 121, 121f, 128f,
129, 132f, 133
right lung, 129, 129f
right middle lobe, 116f, 117, 118f, 119, 121, 121f, 132f,
133
right upper lobe, 116f, 117, 118f, 119, 119f, 126f, 127,
130f, 131
signs of, 116f, 117, 121, 122f, 123, 124f, 125
Colon
density of, 86f, 87
splenic flexure of, 40f, 41
Computed tomography, 22f, 23, 56–69
air bronchogram sign on, 106f, 107
aorta on, 58f, 59, 91, 91f, 156f, 157
aortic arch on, 26f, 27, 58f, 59, 90f, 91, 156f, 157
axial, 24f, 25
bones on, 56f, 57, 62f, 63
bronchi on, 102f, 103
bronchiectasis on, 104f, 105, 105f
bullae on, 150f, 151
contrast media in, 26f, 27, 56f, 57
coronal, 24f, 25
densities on, 26f, 27, 34f, 35, 63
emphysema on, 150f, 151, 152f, 153
granuloma on, 148f, 149
heart on, 156f, 157
high-resolution, 62f, 63, 66f, 67
honeycombing on, 140f, 141
Hounsfield units for, 26f, 27, 34f, 35, 63
hydrothorax on, 129, 129f
interstitial thickening on, 136f, 137
linear, 136f, 137, 138f, 139
nodular, 136f, 137, 138f, 139
Kerley B lines on, 204f, 205
loculated pleural effusion on, 184f, 185
lung cancer on, 28f, 29, 152f, 153, 231f
lungs on, 56f, 57, 60f, 61, 64f, 65
lymph nodes on, 156f, 157
major fissure on, 79, 79f
mediastinal trauma on, 170f, 171
mediastinum on, 25, 25f, 26f, 27, 56f, 57, 58f, 59, 
156f, 157
oblique, 22f, 26f
pericardial effusion on, 207, 207f
planes for, 64f, 65, 68f, 69, 69f
pleural air on, 186f, 187
pleural effusion on, 178f, 179
pneumothorax on, 186f, 187
pulmonary vessels on, 28f, 29
sagittal, 24f, 25
scout view for, 56f, 57, 58f, 59
superior vena cava on, 26f, 27
thymic mass on, 162f, 163
upper abdomen on, 62f, 63
Congestive heart failure. See Heart failure
Consolidation. See also Alveolar filling disease
left lower lobe, 94f, 95
left upper lobe, 96f, 97, 101, 144f, 145
lingula, 92f, 93, 100f, 101, 110f, 111
multifocal, 145
right lower lobe, 94f, 95, 100f, 101, 114f, 115, 121,
121f, 142f, 143
right middle lobe, 78f, 79, 92f, 93, 94f, 95, 100f, 101,
118f, 119
right upper lobe, 68f, 69, 69f, 96f, 97, 118f, 119, 142f, 143
Contrast media
bronchial, 103, 104f, 105
CT, 26f, 27, 56f, 57
esophageal, 166f, 167
COPD. See Chronic obstructive pulmonary disease
(COPD)
Coronal plane, 64f, 65, 69, 69f
Costophrenic sulcus (angle), 36f, 37, 38f, 39, 174f, 175
shallow (blunt), 176f, 177, 179, 181, 181f
Cross-sectional imaging, 22f, 23–35. See also Computed
tomography; Magnetic resonance imaging;
Ultrasonography
axial, 22f, 23
coronal, 22f, 23
oblique, 22f, 23
sagittal, 22f, 23
CT. See Computed tomography
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Index 239
D
Decubitus position
for effusion, 8f, 9
for pneumothorax, 10f, 11
left lateral, 8f, 9
right lateral, 10f, 11, 16f, 17
Densities
on computed tomography, 26f, 27, 34f, 35
on plain film, 27, 86f, 87, 88f, 89
Descending aorta. See Aorta, descending
Diaphragm, 2f, 8f, 9, 40f, 41, 92f, 93
atelectasis-related shift of, 125
density of, 88f, 89
free air under, 54f, 55
height of, 12f, 13
hyperinflation and, 150f, 151
left, 36f, 37, 76f, 77, 88f, 89
elevated appearance of, 8f, 9
on lateral view, 90f, 91
silhouette sign and, 90f, 91, 98f, 99, 122f, 123
medial, silhouette sign and, 110f, 111
on computed tomography, 62f, 63
on lateral view, 90f, 91
right, 38f, 39f, 88f, 89
on lateral view, 90f, 91
silhouette sign and, 88f, 89, 90f, 91, 119, 119f
subpulmonic fluid and, 178f, 179, 180f, 181, 183
E
Echocardiogram, 32f, 33
pericardial effusion on, 206f, 207
Edema
alveolar, 202f, 203
interstitial, 202f, 203
Effusion
pericardial. See Pericardial effusion
pleural. See Pleural effusion
Electrocardiogram lead, 208f, 209
Emphysema, 20f, 21, 150f, 151, 152f, 153. See also
COPD (chronic obstructive pulmonary disease)
Empyema, 32f, 33
Endotracheal tube, 208f, 209
Esophagram, 166f, 167
Esophagus
feeding tube in, 167, 167f
on computed tomography, 58f, 59, 156f, 157
Expiratory film, 12f, 13
air trapping on, 14f, 15
pneumothorax on, 17
Extrapleural space, 175, 190f, 191
F
Fat, 86f, 87
density of, 27, 86f, 87
Feeding tube, 167, 167f
Felson’s axioms, 210
Fibrosis, pulmonary, 130f, 131
Fissure(s)
accessory, 80f, 81, 82f, 83
azygos, 80f, 81, 84f, 85
inferior accessory, 80f, 81, 84f, 85
interlobular, 70f, 71
major (oblique), 72f, 73, 84f, 85
edge appearance of, 74f, 75
fluid in, 74f, 75, 176f, 177, 184f, 185, 227f, 228
in left upper lobe collapse, 120f, 121
in right middle lobe collapse, 118f, 119
in right middle lobe consolidation, 78f, 79
Fissure(s) (Continued)
line appearance of, 74f, 75
on computed tomography, 60f, 61, 79, 79f
on lateral view, 76f, 77
shiftof, 116f, 117, 118f, 119, 120f, 121
thickness of, 74f, 75
minor (horizontal), 74f, 75, 75f, 84f, 85
downward slope of, 75
fluid in, 184f, 185, 227f, 228
in right lower lobe collapse, 121, 121f
in right middle lobe collapse, 118f, 119, 121, 121f
in right middle lobe consolidation, 78f, 79
in right upper lobe collapse, 118f, 119
on lateral view, 76f, 77
shift of, 116f, 117, 118f, 119, 119f, 120f, 121
superior accessory, 80f, 81, 84f, 85
Fluid
alveolar. See Alveolar filling disease
density of, 20f, 21
fissural, 74f, 75, 176f, 177, 184f, 185, 227f, 228
pericardial, 197, 206f, 207, 221f, 222
pleural. See Pleural effusion
subpulmonic, 178f, 179, 180f, 181, 183
Fluoroscopy, 17
Foreign body, aspiration of, 84f, 85, 85f
Fracture, rib, 190f, 191
G
Gas. See also Air
density of, 86f, 87
in abdominal structures, 38f, 39, 40f, 41
Granuloma, 148f, 149
Gravity, 178f, 179
Grid, 18f, 19, 19f
Gunshot wound, 174f, 175, 217f, 218
H
Heart, 36f, 37, 38f, 39, 45, 45f
density of, 86f, 87, 88f, 89
enlargement of, 196f, 197, 198f, 199, 233f, 234
lateral view of, 194f, 195
left, 194f, 195
border bulge of, 196f, 197
enlargement of, 196f, 197, 198f, 199, 233f, 234
mediastinum relationship to, 154f, 155
left shift of, 116f, 117
on computed tomography, 156f, 157
right, 88f, 89, 194f, 195
enlargement of, 197, 198f, 199
mediastinum relationship to, 154f, 155
shift of, 116f, 117, 125
size of, 3, 11, 12f, 13, 196f, 197
ultrasonography of, 32f, 33, 206f, 207
Heart failure
case study of, 227f, 228
cephalization in, 200f, 201, 205
edema with, 202f, 203, 205
left, 200f, 201, 202f, 203, 227f, 228
pleural effusion in, 203, 206f, 207
pseudotumor in, 185
supine view of, 204f, 205
Hemithorax, white, 136f, 137, 182f, 183
Hemorrhage, mediastinal, 158f, 159, 170f, 171, 192f, 193
Hemothorax, gunshot wound and, 217f, 218
Hernia, hiatal, 166f, 167
Hilum, 36f, 37, 38f, 39, 171
adenopathy of, 170f, 171
displacement of, 125, 130f, 131
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240 Index
Hilum (Continued)
left, 124f, 125
right, 44f, 45, 124f, 125, 156f, 157
Honeycombing, 140f, 141
Hounsfield units, 26f, 27, 34f, 35, 63
Hydropneumothorax, 189
Hydrothorax, 129, 129f. See also Pleural effusion
Hyperinflation, 150f, 151
compensatory, 125
Hyperlucency, 150f, 151
Hypoventilation atelectasis, 130f, 131
I
Inferior accessory fissure, 80f, 81, 84f, 85
Inspiration, 11, 12f, 13
Interlobular fissure, 70f, 71
Interstitium, 50f, 51, 66f, 67, 134f, 135
acute disease of, 139, 141
chronic disease of, 139
diffuse disease of, 138f, 139, 140f, 141, 153
alveolar consolidation and, 67, 67f, 144f, 145
edema of, 202f, 203
focal disease of, 138f, 139
on computed tomography, 66f, 67, 67f
thickening of, 136f, 137, 138f, 139
Intrafissural effusion, 74f, 75, 176f, 177, 184f, 185, 227f,
228
Intrapleural air. See Pneumothorax
K
Kerley B lines, 202f, 203, 204f, 205
L
Lateral decubitus position
left, 8f, 9
right, 10f, 11, 16f, 17
Lateral view, 4f, 5
aorta on, 38f, 39, 90f, 91, 154f, 155, 194f, 195
diaphragm on, 90f, 91
fissures on, 76f, 77
heart on, 194f, 195
mediastinum on, 160f, 161, 162f, 163
“normal” silhouette sign on, 90f, 91
of esophagram, 166f, 167
pleural fluid on, 8f, 9, 176f, 177
search pattern for, 48f, 49
structures on, 36f, 37, 38f, 39
Left anterior oblique position, 7
Left atrial appendage, 194f, 195, 197
Left lateral decubitus position, 8f, 9, 178f, 179
Left lower lobe, 72f, 73, 76f, 77, 92f, 93
bronchiectasis of, 105, 105f
collapse of, 116f, 117, 122f, 123, 124f, 125, 128f, 129
consolidation in, 94f, 95
on computed tomography, 62f, 63
pneumonia of, 98f, 99, 106f, 107
Left upper lobe, 72f, 73, 76f, 77
air bronchogram sign in, 108f, 109
collapse of, 116f, 117, 120f, 121, 132f, 133
consolidation in, 96f, 97, 101, 144f, 145
Linear artifact, 4f, 5
Lingula, 76f, 77
collapse of, 119, 120f, 121, 132f, 133
consolidation in, 92f, 93, 96f, 97, 100f, 101, 110f, 111
Liver, 40f, 41, 42f, 43
density of, 88f, 89
on computed tomography, 62f, 63
Lobes. See Left lower lobe; Left upper lobe; Lingula;
Right lower lobe; Right middle lobe; Right upper
lobe
Lordotic view, 17
Lower lobes. See Left lower lobe; Right lower lobe
Lung(s)
abscess of, 215f, 216
air in, 19, 20f, 21, 86f, 87. See also Air bronchogram
sign
alveoli of. See Alveoli
atelectasis. See Atelectasis
blackness of, 12f, 13, 14f, 15, 27
bronchus of. See Bronchus (bronchi)
collapse of. See Collapse
consolidation in. See Consolidation
density of, 86f, 87
fissures of. See Fissure(s)
interstitium of. See Interstitium
lobes of. See Left lower lobe; Left upper lobe;
Lingula; Right lower lobe; Right middle lobe;
Right upper lobe
mass of, 146f, 147. See also Lung cancer
cavitary, 146f, 147, 148f, 149
fissural fluid simulation of, 184, 185f
hilar, 170f, 171, 172f, 173, 231f, 232
size of, 146f, 147 vs. nodule, 146f, 147
nodule of, 122f, 123
metastatic, 213f, 214
multiple, 136f, 137
on computed tomography, 136f, 137, 138f, 139
size of, 146f, 147 vs. nodule, 146f, 147
normal, 54f, 55
search pattern for, 46f, 47, 47f, 48f, 49
spot on, 146f, 147
white, 136f, 137, 182f, 183
Lung cancer, 147, 152f, 153
case study of, 225f, 226, 231f, 232
on computed tomography, 28f, 29, 152f, 
153, 231f
Lymph nodes
hilar, 170f, 171, 172f, 173
mediastinal, 156f, 157, 164f, 165
Lymphoma, 172f, 173
M
Magnetic resonance imaging, 22f, 23, 29
cardiac cycle on, 30f, 31
contraindications to, 31
gray scale of, 31
mediastinum on, 30f, 31
of neural tumor, 169, 169f
Magnification, 3
Main stem bronchus, right, 156f, 157
Major fissures. See Fissure(s), major (oblique)
Mass
mediastinal. See Mediastinum, mass of
over spine, 168f, 169
pulmonary, 146f, 147. See also Lung cancer
cavitary, 146f, 147, 148f, 149
fissural fluid simulation of, 184, 185f
hilar, 170f, 171, 172f, 173, 231f, 232
size of, 146f, 147
thymic, 158f, 160, 162f, 163, 223f, 224
Mastectomy, 54f, 55
Mediastinum, 154–173
adenopathy of, 164f, 165
anterior, 160f, 161, 162f, 163, 173
borders of, 154f, 155
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Index 241
Mediastinum (Continued)
compartments of, 160f, 161
density of, 88f, 89
five T’s of, 163, 173, 224
hemorrhage in, 158f, 159, 170f, 171, 192f, 193
lateral view of, 160f, 161, 162f, 163
lymph nodes of, 156f, 157, 164f, 165
magnetic resonance imaging of, 30f, 31
mass of
anterior compartment, 162f, 163
lateral view of, 162f, 163
middle compartment, 160f, 161, 164f, 165, 167,
172f, 173
posterior compartment, 168f, 169, 169f
silhouette sign and, 98f, 99, 160f, 161
tracheal displacement by, 158f, 159, 160f, 161,
172f, 173
middle, 160f, 161, 163, 164f, 165, 166f, 167, 173
on computed tomography, 25, 25f, 26f, 27, 56f, 57,
58f, 59, 156f, 157
posterior, 160f, 161, 168f, 169, 169f, 173
search pattern for, 44f, 45, 45f
shift of, 188f, 189
trauma to, 170f, 171
vascular structures of, 166f, 167, 168f
widening of
diffuse, 158f, 159, 163, 170f, 171, 192f, 193
focal, 158f, 159, 163, 172f, 173
Meniscus, 176f, 177, 179
Metal, density of, 20f, 21, 27, 86f, 87
Metallic artifact, 4f, 5
Metastasis
pulmonary, 213f, 214
rib, 190f, 191
Minor fissures. See Fissure(s), minor (horizontal)
Mitral valve stenosis, 201
MRI. See Magnetic resonance imaging
Multiple myeloma, 168f, 169
Muscle, density of, 86f, 87
N
Nasogastric tube, 208f, 209
Neural tumor, 169, 169f
Nodule(s). See also Mass
metastatic, 213f, 214
multiple, 136f, 137
on computed tomography, 136f, 137, 138f, 139
right upper lobe, 122f, 123
size of, 146f, 147
Normal chest x-ray, 37–61. See also specific structures
O
Oblique views, 6f, 7, 16f, 17
Obstructive atelectasis
central, 126f, 127, 129, 129f, 131
peripheral, 127
Obstructive pulmonary disease, chronic (COPD), 20f,
21, 150f, 151, 152f, 153
P
Pajama snap, 4f, 5
Parietal pleura, 71
Passive (relaxation) atelectasis, 129, 129f
Pericardial effusion, 197, 206f, 207, 221f, 222
Pericardium, on computed tomography, 59, 59f
Photons, 18f, 19, 19f
Pin, aspiration of, 84f, 85, 85f
Pleura
mediastinal mass displacement of, 159
on computed tomography, 59, 59f
parietal, 71
visceral, 60f, 61, 71
Pleural effusion
air-fluid level with,188f, 189
case study of, 221f, 222
encapsulated (loculated), 183, 184f, 185
fissural, 74f, 75, 176f, 177, 184f, 185, 227f, 228
in heart failure, 203, 206f, 207
mediastinal shift and, 182f, 183
on computed tomography, 178f, 179
on lateral decubitus view, 8f, 9, 176f, 177
on supine view, 182f, 183, 192f, 193
on ultrasonography, 32f, 33
shallow (blunt) costophrenic angle and, 176f, 177,
180f, 181, 181f
subpulmonic, 178f, 179, 180f, 181, 183
white lung with, 182f, 183
Pleural space (cavity), 71, 174f, 175
air in. See Pneumothorax
bullet in, 174f, 175
fluid in. See Pleural effusion
Pneumonia, 79
air-fluid level in, 148f, 149
case study of, 219f, 220, 225f, 226
left lower lobe, 98f, 99, 106f, 107
right lower lobe, 100f, 101
right middle lobe, 100f, 101
silhouette sign and, 98f, 99, 100f, 101
Pneumothorax, 10f, 11
air-fluid level with, 188f, 189
lung collapse and, 122f, 123
on decubitus film, 10f, 11
on expiratory film, 17
on supine view, 186f, 187, 192f, 193
tension, 188f, 189, 219f, 220
Portable x-ray, 2f, 3, 204f, 205
Posteroanterior (PA) view, 1, 2f, 3, 4f, 16f, 17
inspiratory vs. expiratory, 12f, 13, 14f, 15
right anterior oblique position for, 6f, 7
search pattern for, 41
abdomen, 40f, 41
lungs, 46f, 47, 47f, 48f, 49
mediastinum, 44f, 45, 45f
thorax, 42f, 43
structures on, 36f, 37, 38f, 39
Pseudoaneurysm, 170f, 171
Pseudotumor, 184f, 185
Pulmonary artery, 60f, 61, 102f, 103, 134f, 135
left, 154f, 155, 156f, 157
main, 58f, 59, 156f, 157, 194f, 195
on computed tomography, 28f, 29, 58f, 59
right, 58f, 59, 154f, 155
Pulmonary fibrosis, collapse and, 130f, 131
Pulmonary lobule, 50f, 51
Pulmonary vein, 60f, 61, 102f, 103, 134f, 135
on computed tomography, 28f, 29
R
Radiation, 18f, 19, 19f
Radiation safety, 33
Radiodense, 19, 27
Radiolucent, 19, 27
Retrosternal clear space, 150f, 151, 154f, 155
Rib
anterior, 42f, 43
fracture of, 190f, 191
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242 Index
Rib (Continued)
metastasis to, 190f, 191
on computed tomography, 62f, 63
posterior, 42f, 43
Right anterior oblique position, 6f, 7, 16f, 17
Right lateral decubitus position, 10f, 11, 16f, 17
Right lower lobe, 73, 76f, 77, 92f, 93
air bronchogram sign in, 108f, 109
collapse of, 116f, 117, 119, 119f, 121, 121f, 128f, 129,
132f, 133
consolidation in, 88f, 89, 94f, 95, 100f, 101, 114f, 115,
142f, 143
inferior accessory fissure of, 82f, 83
pneumonia in, 100f, 101
superior accessory fissure of, 82f, 83
Right middle lobe, 76f, 77
collapse of, 116f, 117, 118f, 119, 121, 121f, 132f, 133
consolidation in, 78f, 79, 92f, 93, 94f, 95, 96f, 97, 100f,
101, 118f, 119
pneumonia in, 100f, 101
Right upper lobe, 76f, 77
air bronchogram sign in, 108f, 109
collapse of, 110f, 111, 116f, 117, 118f, 119, 119f, 126f,
127, 130f, 131
consolidation in, 96f, 97, 118f, 119, 142f, 143
nodule in, 122f, 123
S
Safety, 33
Sagittal plane, 64f, 65, 68f, 69
Scapula, 42f, 43
on computed tomography, 62f, 63
Scar, 148f, 149
Scattered x-rays, 18f, 19
Sharpness, 3
Silhouette sign, 86–101
absence of, 143, 145
alveolar filling disease/consolidation and, 92f, 93,
94f, 95, 96f, 97, 142f, 143, 145
aorta and, 96f, 97
definition of, 89
left diaphragm and, 98f, 99
left heart and, 92f, 93, 100f, 101
medial diaphragm and, 110f, 111
mediastinal mass and, 98f, 99, 160f, 161
misleading, 98f, 99
normal, 90f, 91, 98f, 99
pneumonia and, 98f, 99, 100f, 101
right diaphragm and, 100f, 101, 119, 119f
right heart and, 94f, 95, 100f, 101
underpenetrated film and, 98f, 99
vs. air bronchogram sign, 106f, 107. See also Air
bronchogram sign
Soft tissue, density of, 20f, 21, 26f, 27, 86f, 87, 88f, 89
Sonography. See Ultrasonography
Spine
mass over, 168f, 169
on computed tomography, 62f, 63
Splenic flexure, 38f, 39, 40f, 41
on computed tomography, 62f, 63
Stenosis
mitral, 201
tracheal, 24f, 25
Sternum
hyperinflation and, 150f, 151
on computed tomography, 62f, 63
Stomach, 36f, 37, 40f, 42f, 43
on computed tomography, 62f, 63
Stomach bubble, 36f, 37, 40f, 41
Stomach bubble sign, 180f, 181, 181f
Styrofoam cup x-ray, 148f, 149
Subpulmonic effusion, 178f, 179, 180f, 181, 183. 
See also Pleural effusion
Superior accessory fissure, 80f, 81, 84f, 85
Superior vena cava, 154f, 155, 156f, 157, 194f, 195
catheter in, 4f, 5
on computed tomography, 26f, 27, 58f, 59
Supine view
blood flow and, 201
heart failure on, 204f, 205
pleural effusion on, 182f, 183, 192f, 193
pneumothorax on, 187, 192f, 193
T
Ten Axioms, 210
Tension pneumothorax, 188f, 189, 219f, 220
Terrapin, 235f, 236
Thorax, search pattern for, 42f, 43
Thymus
mass of, 158f, 160, 162f, 163, 223f, 224
on computed tomography, 58f, 59
Tomography, 17
computed. See Computed tomography
Trachea, 36f, 37, 38f, 39, 45, 45f, 156f, 157
compression of, 158f, 159, 160f, 161
density of, 88f, 89
displacement of
left lung collapse and, 116f, 117
mediastinal mass and, 158f, 159, 160f, 161, 172f, 173
right upper lobe collapse and, 119f, 125, 130f, 131
on computed tomography, 58f, 59
right wall of, 154f, 155
stenosis of, 24f, 25
three-dimensional view of, 29, 29f
Trauma, mediastinal, 170f, 171, 192f, 193
Tube
endotracheal, 208f, 209
feeding, 167, 167f
nasogastric, 208f, 209
Tumor
mediastinal. See Mediastinum, mass of
metastatic, 190f, 191, 213f, 214
pulmonary. See Lung(s), mass of; Lung cancer
thymic, 158f, 160, 162f, 163, 223f, 224
vertebral destruction with, 168f, 169
Turtle, 235f, 236
U
Ulcer, perforation of, 233f, 234
Ultrasonography, 22f, 23, 32f, 33
empyema on, 32f, 33
pleural effusion on, 32f, 33
subpulmonic effusion on, 178f, 179
Underpenetrated film, 98f, 99
Upper lobes. See Left upper lobe; Right upper lobe
V
Vena cava, superior, 154f, 155, 156f, 157, 194f, 195
catheter in, 4f, 5
on computed tomography, 26f, 27, 58f, 59
Ventricle. See also Heart
left, 194f, 195, 199
enlargement of, 198f, 199, 233f, 234
on computed tomography, 58f, 59, 156f, 157
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Index 243
Ventricle (Continued)
right, 194f, 195
on computed tomography, 58f, 59, 156f, 157
Vertebral body
multiple myeloma of, 168f, 169
on computed tomography, 62f, 63
View(s)
anteroposterior (AP), 2f, 3, 16f, 17
apical lordotic, 17
decubitus, 8f, 9, 10f, 11, 16f, 17
lateral, 4f, 5. See also Lateral view
oblique, 6f, 7, 16f, 17
posteroanterior (PA), 1, 2f, 3, 4f, 16f, 17
inspiratory vs. expiratory, 12f, 13, 14f, 15
right anterior oblique position for, 6f, 7
search pattern for. See Viewing sequence
structures on, 36f, 37, 38f, 39
Viewing sequence, 41, 135
abdomen, 40f, 41
lungs, 46f, 47, 47f, 48f, 49
mediastinum, 44f, 45, 45f
thorax, 42f, 43
Visceral pleura, 60f, 61, 71
Visceral pleural line, 186f, 187
W
Water, density of, 27, 86f, 87
Wheezing, 15
White lung, 136f, 137, 182f, 183
X
X-ray beam, 18f, 19, 19f
X2923_Idx 10/25/06 3:48 PM Page 243
	Cover
	Felson's Principles of Chest Roentgenology, 3rd Edition
	ISBN: 9781416029236
	Copyright
	Dedication
	Preface
	Credits
	Instructions
	Compact Disk contents
	THE RADIOGRAPHIC EXAMINATION
	CROSS-SECTIONAL IMAGING TECHNIQUES
	THE NORMAL CHESTX-RAY: READING LIKE THE PROS
	CHEST CT: PUTTING IT TOGETHER
	LOBAR ANATOMY
	THE SILHOUETTE SIGN
	THE AIR BRONCHOGRAM SIGN
	SIGNS OF LUNG AND LOBAR COLLAPSE
	PATTERNS OF LUNG DISEASE
	THE MEDIASTINUM
	THE PLEURAL AND EXTRAPLEURAL SPACES
	CARDIOVASCULAR DISEASE
	Felson’s 10 Axioms for a Lifetime of Learning in Medicine
	A DOZEN GREAT CASES
	Index