MRI in Inflammatory Myopathies and Autoimmune-Mediated Myositis

Abstract

In this chapter, dermatomyositis, polymyositis, inclusion body myositis, and the necrotizing myopathies are discussed in detail with regard to their clinical features, laboratory and histopathological findings, mimics and the imaging findings with magnetic resonance imaging, computed tomography, and ultrasound. With the focus on magnetic resonance imaging, its discriminating role between disorders during the diagnostic work-up, the evaluation of the extent and activity of the disease, and the gathering of information on fat replacement of muscles are considered. Furthermore, its use to locate the best site for a muscle biopsy to enhance the diagnostic yield of a histopathologically confirmed diagnosis and its use during the follow-up of patients in assessing the therapeutic effect of immunosuppressive and immunomodulating therapies and to detect signs of relapse are outlined.