Article

MRI of muscle is becoming an increasingly useful diagnostic tool. Multiple studies have now indicated that increased signal intensity noted on MR images of specific denervated muscles corresponds closely with abnormalities on EMG. Further, there are many newer forms of MRI and applied MR technology, including functional MRI, contrast enhanced spin-echo MRI, and more modern MRS. These techniques are allowing MR to play a growing role in the functional and dynamic evaluation of skeletal muscle pathology and injury, body composition, and cardiac disease. Despite these advances in the use of MRI, there are definite limitations. Clinically available MRI still requires the subject to be relatively motionless. This limits its usefulness as a functional assessment tool. Further, available data confirm that MRI is less sensitive in detecting muscle denervation than needle EMG. The degree of abnormality in complete versus incomplete axonal lesions, and the imaging changes occurring with reinnervation, have not been systematically studied. Presently, electrodiagnostic studies are still necessary to differentiate a complete from an incomplete axonal lesion. Better, less subjective, methods of quantifying MR signal intensity need to be developed. With respect to denervation, longitudinal, serial studies in the same patient over an extended time are needed to better define the usefulness of MRI in terms of sensitivity and specificity in relation to time after nerve injury.

Langue : ANGLAIS