FUNDAMENTOS DPI - Musculoesquelético

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Princípios de Radiologia 
Musculoesquelética 
Sistema Musculoesquelético 
IMAGING TECHNIQUES AND 
FUNDAMENTAL OBSERVATIONS FOR THE 
MUSCULOSKELETAL SYSTEM 
ADAM, Andy et al. (Ed.). Grainger & Allison's diagnostic radiology. 
Churchill Livingstone Elsevier, 2008. 
Radiography 
• Preliminary evaluation; 
• Contrast between tissues such as fat and 
muscle and bone; 
• Two views of a body part are typically taken; 
• Lateral plane and the anteroposterior (AP) 
plane, which is termed dorsopedal (DP) in the 
feet and dorsopalmar (DP) in the hands. 
• In complex anatomical areas or when specific 
information is needed, additional or 
alternative views are frequently obtained. 
 
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 R
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As cinco densidades em ordem de aumento de densidade: Ar, 
gordura, Líquido, Osso, Metal. 
Radiography 
• Benefits 
• Radiographs also provide initial soft-tissue 
assessment and can demonstrate soft-tissue 
swelling as well as joint effusions, which can 
be particularly useful in areas where bony 
abnormality may be radiographically occult. 
Radiography 
• Disadvantages 
• As in other areas of the body, artefact from 
external structures such as clothing and from 
overlapping structures can be misinterpreted 
as an abnormality. 
• Some sites can be difficult to appreciate fully 
using radiographs. 
 
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(A) AP radiograph of index finger 
demonstrates dislocation of the 
proximal interphalangeal joint (arrow). 
 
(B) Dislocated distal interphalangeal 
joint is only evident on the orthogonal 
view (arrow). 
(A) Lateral radiograph of the elbow shows joint effusion displacing the fat pads 
(*) indicating intra-articular injury. 
(B) Horizontal beam lateral radiograph of the knee shows lipohaemarthrosis due to occult 
fracture with a linear fat (white arrow)/fluid (black arrow) level. 
Advances and Variations 
• Stress Views. Standard radiographs allow 
static evaluation of musculoskeletal 
structures. 
• Imaging a joint under passive or active stress 
may also provide indirect assessment of 
ligamentous injury. 
• For example, comparative flexion and 
extension views of the cervical spine provide 
valuable information regarding stability of the 
atlantoaxial joint. 
Advances and Variations 
• Fluoroscopy. 
• Provide real-time dynamic video images; 
• Guide interventional procedures such as 
needle placement and fracture reduction; 
 
Advances and Variations 
• Arthrography. 
• Injection of a radio-opaque contrast medium 
into a joint usually guided by fluoroscopy, 
although US guidance can be used as an 
alternative. 
• Distension of the joint provides indirect 
information about the soft tissues which can 
be deduced from the distribution of the 
injected contrast medium. 
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Computed Tomography (CT) 
• Benefits 
• CT is ideally suited for the evaluation of bony 
structures and soft-tissue calcification and 
provides excellent spatial resolution and 
demarcation of bony structure and detail. 
• Despite its limitations in assessment of muscle 
and fat, CT has a role in imaging patients in whom 
MRI is contraindicated and can be combined with 
the injection of intra-articular iodinated contrast 
media in a similar way to the more widely utilised 
MR arthrography. 
Magnetic Resonance Imaging (MRI) 
• The advent of MRI revolutionised the imaging 
of musculoskeletal structures, providing 
unequalled direct assessment of soft tissues 
and joints. 
• Benefits 
• MR images are generated by the effect of a 
strong magnetic field on the hydrogen nuclei 
in water molecules, thereby avoiding the 
potential risks of ionising radiation. 
 
Magnetic Resonance Imaging (MRI) 
• Disadvantages 
• Because of the strong magnetic field strength, 
many implantable medical devices such as cardiac 
pacemakers are considered to be unsafe. 
• Ferrous materials also cause significant difficulty 
for the radiologist due to susceptibility artefact 
from image distortion and signal voids. 
• Modern orthopaedic prostheses produced from 
titanium and other non-ferrous materials are less 
problematic than older devices but can still 
provide a challenge. 
NORMAL IMAGING APPEARANCES - 
Radiography 
• Radiographs provide an excellent primary assessment 
of bone and joint conditions. In the case of trauma, 
radiographs reliably identify fractures and dislocation. 
• They provide useful assessment of painful bones and 
joints and are invaluable for the review of bony 
deformity and anatomical variation. 
• Normal bone has a dense cortex of varying thickness. 
• Radiographs demonstrate a distinct corticomedullary 
junction and within the medulla trabecular structure 
should be appreciated. 
• Different bones have differing ratios of cortex and 
medullary cavity; this affects their radiographic 
appearance and how readily abnormality is 
radiographically visualised when diseased. 
NORMAL IMAGING APPEARANCES - 
Radiography 
• Air, fat and skeletal muscle have differing 
absorption characteristics for ionising 
radiation and it is possible to discriminate 
between them on radiographs. 
• In general, however, radiographs have poor 
sensitivity for the detection of soft-tissue 
abnormalities. 
NORMAL IMAGING APPEARANCES - 
Computed Tomography 
• Bony cortex is a dense high-attenuation layer 
thinning at the metaphyses and epiphyses of 
long bones. 
• Individual trabeculae can be appreciated 
within the medullary cavity on CT. 
• Bone is a dynamic organ and alterations in 
bone morphology can indicate disease 
processes: for example, the presence of 
osteophytes in osteoarthrosis. 
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NORMAL IMAGING APPEARANCES - 
Computed Tomography 
• Even by adjusting the window and level 
parameters to maximise contrast between 
adjacent soft-tissue elements, it is not usually 
possible to differentiate normal from 
abnormal soft-tissue structures in 
musculoskeletal disease. 
• Conversely, although the attenuation values of 
fat and skeletal muscle differ enough that they 
can be distinguished as separate tissues, this is 
seldom useful clinically. 
NORMAL IMAGING APPEARANCES - 
MRI 
• With its ability to differentiate fatty and 
haematopoietic marrow, MRI is a valuable 
technique for non-invasive marrow 
assessment. 
• The appearance of normal bone marrow on 
MRI is determined by the pulse sequence 
parameters and the marrow constituents, 
particularly the proportion of fat cells but also 
the relative quantities of water and trabecular 
matrix. 
NORMAL IMAGING APPEARANCES - 
MRI 
• Differentiation between fatty and 
haematopoietic marrow is best appreciated 
on T1-weighted sequences. 
• Yellow or fatty marrow has signal 
characteristics similar to those of 
subcutaneous fat on T1-weighted imaging. 
• On T2-weighted sequences fatty marrow 
signal intensity is typically higher than muscle 
and similar to or slightly lower than 
subcutaneous fat. 
NORMAL IMAGING APPEARANCES - 
MRI 
• On T1-weighted imaging, haematopoietic 
marrow signal is lower than yellow marrow 
but still higher than that of the intervertebral 
discs and muscle. 
• Red marrow has a similar or slightly higher 
signal than skeletal muscle on both T1- and 
T2-weighted imaging. 
NORMAL IMAGING APPEARANCES - 
MRI 
• Red marrow returns intermediate signal 
similar to skeletal muscle, whereas yellow 
marrow signal is lowerthan muscle on fluid-
sensitive, fat-suppression sequences such as 
STIR or fat-saturated T2 (T2fs) sequences. 
• These sequences can be used to emphasise 
the conspicuity of abnormal processes as the 
majority will cause increased fluid signal. 
NORMAL IMAGING APPEARANCES - 
MRI• Normal fat returns returns high signal on both T1- and fast 
spin-echo (FSE) T2-weighted sequences and signal should 
be uniformly saturated (decreased) using fat suppression 
sequences such as STIR or spectral fat suppression. 
• Normal skeletal muscle signal is slightly higher than water 
and much lower than fat on T1-weighted sequences. 
• On T2-weighted sequences skeletal muscle signal is much 
lower than both fat and fluid and on STIR or T2fs sequences 
normal muscle signal is higher than fat and lower than fluid 
• Tendons and ligaments are both chiefly composed of type 1 
collagen and have a similar MR appearance, being of low 
signal on all conventional sequences. 
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Coronal MR images of a skeletally immature patient. (A) T1-weighted and (B) 
proton density fat-saturated images showing yellow marrow in the epiphyses (Y) 
and red marrow in the metadiaphyses (R). 
Axial MR images through the mid-thigh. (A) T1-and (B) T2-weighted fat-saturated 
images showing skin, normal fat distribution, muscle and bone. 
Referências 
• ADAM, Andy et al. (Ed.). Grainger & Allison's diagnostic radiology. 
Churchill Livingstone Elsevier, 2008. 
• BRANT, William E.; HELMS, Clyde A. (Ed.). Fundamentals of 
diagnostic radiology. Lippincott Williams & Wilkins, 2012. 
• Jackson, A. "Textbook of radiology and imaging, Vols 1 & 2 (7th 
edn). Edited by D Sutton, pp. 1856, 2003 (Elsevier Science Ltd, 
Edinburgh, UK) 
• Juhl, J. H.; Crummy, A. B.; Kuhlman, J. E.. Paul and Juhl's Essentials 
of Radiologic Imaging. 1998, Lippincott-Raven - Philadelphia. 
• OUELLETTE, Hugue. The Teaching Files: Musculoskeletal. Elsevier 
Health Sciences, 2009. 
• WEBB, Wayne Richard; BRANT, William E.; MAJOR, Nancy M. 
Fundamentals of body CT. Elsevier Health Sciences, 2006. 
 
• GAILLARD, F. Appendicolith; Radiopaedia. org. 2014. 
• William Herring. LEARNING RADIOLOGY, 2014