Pains, strains, and fasciculations: lower extremity muscle disorders.

Muscle injuries that were suspected only on the basis of clinical examination are now readily demonstrated and characterized using MR imaging. Imaging is used not only for assessment of location, type, and severity of muscle injuries; it plays an important role in treatment planning, and the detection of complications. MR imaging also is useful in nontraumatic muscle disorders including congenital, inflammatory, and infectious myositis, and in cases of denervation, MR imaging is valuable for diagnosis, staging, and prognostication. In cases where the origin of myopathy is unknown, MR imaging can direct biopsy to increase diagnostic yield.