INTEREST OF MUSCLE MRI IN INFLAMMATORY MYOPATHIES

Primary inflammatory myopathies comprise three main entities, distinguished according to clinical and immunohistochemical aspects: polymyositis (PM), dermatomyositis (DM) and inclusion myositis (IBM). These three conditions share a common dysimmune inflammatory involvement of striated muscles, and are characterized by a high degree of clinical and evolutionary polymorphism [1] [2]. Diagnosis of idiopathic inflammatory myopathy (IIM) is based on clinical examination, muscle enzymes, electromyography and proximal muscle biopsy [1] [2] [3]. Today, new investigative techniques and biological markers (anatomopathological, immunological, genetic and imaging techniques) have made it possible to refine the initial diagnostic criteria, offering a more precise diagnostic framework. This more specific diagnostic aid concerns not only DM and PM (the two best-known idiopathic inflammatory myopathies), but also overlapping myositis, autoimmune-mediated necrotizing myopathies (AIMN) and inclusion myositis [4].