THE IDIOPATHIC INFLAMMATORY MYOPATHIES - SPECTRUM OF MR-IMAGING FINDINGS

Magnetic resonance (MR) imaging is useful for demonstrating the soft-t issue and musculature changes seen in patients with idiopathic inflamm atory myopathies (IIMs), These changes include edema within and around muscle, subcutaneous reticulation, muscle calcification, and fatty in filtration of muscle, Muscle edema is visible as areas of hyperintensi ty on short inversion time inversion recovery (STIR) images, Abnormal reticulation of the subcutaneous tissue can be due to subcutaneous ede ma or an infiltrating process; edema from inflammation appears as area s of low signal intensity on T1-weighted images and as areas of high s ignal intensity on STIR images. Intramuscular calcium deposition appea rs as hypointense areas with all pulse sequences, On T1-weighted image s, fatty infiltration appears as areas of high signal intensity within muscles, Because of the improved visualization of muscle inflammation provided by STIR imaging and because MR imaging is noninvasive, it ha s become a useful modality for evaluating patients with IIMs.