Capabilities of magnetic resonance imaging in the diagnosis of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) are a group of chronic autoimmune conditions characterized by proximal muscle weakness and potentially accompanied by a range of extramuscular clinical manifestations. There are subtypes of IIM including dermatomyositis (DM), polymyositis (PM), immune-mediated necrotizing myopathy (IMNM), sporadic inclusion body myositis (sIBM), overlap myositis (OM) with subgroup of anti-synthetase syndrome (ASS) and cancer-associated myositis. Taking into account rarity of the disease, heterogeneity of clinical presentation, difficulties in detection methods and interpretation of myositis associated autoantibodies (MAAs) and myositis specific autoantibodies (MSAs), search for objective imaging methods of muscle damage continues. This is important to definitive diagnosis, predicting subtypes of IIM and case follow-up. One of the most promising methods is magnetic resonance imaging (MRI). The aim of the review was to examine the role of MRI in assessment muscle damage, in particular, most typical MRI-findings and there features in different types of IIM with further clinical cases.