Learning objectives
To recognize the different etiologies concerning striated muscle myopathy.
To view specific patterns and topography of each muscle injury and try to identify a specific cause.
Background
MR fluid-sensitive sequences demonstrate high signal intensityin the skeletal muscle bellies in any condition that increases capillary permeability,
highlighting them from adjacent muscle groups.
That characteristic is found on three main groups concerning myopathies,
which include traumatic,
inflammatory and metabolic etiologies. In order to establish a diagnosis,
a good clinical correlation with the pattern of muscular involvement is necessary,
both on its topography within the human body and the aspect of the muscle itself,
as well as its relation with adjacent planes.
Findings and procedure details
On T1-weighted sequences,
the signal intensity of the striated muscle is generally higher than that of water and much lower than that of the fat.
On inversion-recovery and fat-suppressed T2-weighted images,
normal muscle signal intensity is much lower than that of water but higher than that of fat.
Changes related to T2 prolongation due to muscle edema (intracellular or extracellular free water) are best appreciated in the sequence inversion-recovery and fat-suppressed T2-weighted images.Muscle edema is present in virtually all conditions that influence increased signal intensity....
Conclusion
Due to commonly similar gross pathological features,
along with a relatively non-specific clinical presentation of primary and systemic disorders that affect skeletal muscles,
radiologic assistance plays an important role on the patient assessment.
References
David A.
May,
MD et al.
Abnormal Signal Intensity in Skeletal Muscle at MR Imaging: Patterns,
Pearls,
and Pitfalls. RadioGraphics 2000; 20:S295–S315.
Edward Smitaman,
MD et al.
MR Imaging of Atraumatic Muscle Disorders. RadioGraphics 2018; 38:500–522.
Dyan V.
Flores,
MD et al.
MR Imaging of Muscle Trauma: Anatomy,
Biomechanics,
Pathophysiology,
and Imaging Appearance. RadioGraphics 2018; 38:124–148.
Guermazi A.
et al.
Imaging of Muscle Injuries in Sports Medicine: Sports Imaging Series. Radiology.2017 Mar;282(3):646-663.
Theodorou DJ.
et al.
Skeletal muscle disease: patterns of MRIappearances. Br J Radiol.2012...