Magnetic resonance imaging in focal myositis

We describe 4 cases of focal myositis of the lower leg in which magnetic resonance imaging (MRI) was useful and sensitive in clearly revealing the detailed anatomic extent of muscle change and in guiding muscle biopsy. We also observed a correlation between MRI findings and severity of both clinical and histological manifestations, suggesting that MRI may provide prognostic criteria in focal myositis. MRI may be a helpful, noninvasive test for the followup of focal myositis, in assessing disease progression or resolution.