Ultrasonography, CT, and MRI of muscles in congenital nemaline myopathy.

Twelve patients with congenital nemaline myopathy were examined by ultrasonography and computed tomography (CT) and 4 of them by low-field magnetic resonance imaging (MRI) to investigate the distribution and nature of muscle involvement and to evaluate the yield of these techniques. A pattern of selective muscle involvement was consistently found. Ultrasonography revealed abnormally high muscle echogenicity. In contrast to the controls with simple disuse and/or neurogenic atrophy, CT revealed low muscle density in our patients. MRI confirmed that this pattern reflects patchy, fatty degeneration, a new finding in congenital nemaline myopathy. Ultrasonography appears useful for screening, provided that the dorsiflexors of the feet are examined. CT and MRI can be used to demonstrate abnormalities in mild cases, to select the biopsy site, and for follow-up. MRI, because it provides good soft tissue contrast, is useful for determining fatty infiltration.