[Myositis: diagnostic potential of a magnetic resonance unit with low intensity field (0.2 T)].

Magnetic Resonance Imaging (MRI) is a useful tool for demonstrating muscle changes in patients with inflammatory myopathies. We investigated the diagnostic capabilities of low field (0.2 T) MRI with a dedicated coil in a series of patients with an unquestionable clinical diagnosis of inflammatory myopathy. Infiltrating processes or muscle swelling are depicted as low-signal areas on T1-weighted SE images and as high-signal areas on T2-weighted SE and short time inversion recovery (STIR) images. Fatty infiltration appears as a high-signal area within muscles on T1-weighted SE images. T2-weighted SE and STIR sequences are highly sensitive in demonstrating infiltrating processes or muscle swelling. The signal-to-noise ratio was higher on T2-weighted SE than on STIR images; on the other hand, fast STIR sequences can effectively reduce scan times. To conclude, low field MRI is a useful tool in the study of inflammatory myopathies thanks to its noninvasiveness and to the good depiction of muscle inflammation provided by T2-weighted SE and STIR images.