Value of MRI in diagnostics and evaluation of myositis

Purpose of review This review aims at covering the role of muscle MRI in supporting the diagnosis of myositis, in aiding to differentiate it from other muscle disorders, and in monitoring myositis patients over time by assessing response to treatment and by discriminating between muscle inflammation and chronic damage. Recent findings MRI can assist in 'pattern recognition' of muscle involvement across numerous myopathies, including myositis. Novel applications of magnetic resonance such as cardiac MRI, MR elastography and blood oxigenation level-dependent magnetic resonance can shed light on different aspects of myositis and usefully complement conventional MRI in assessing patients with myositis. Summary MRI can guide therapy by determining whether muscle weakness is related to edema (active inflammation) or muscle atrophy/fat replacement (chronic damage). There is a need to better standardize the assessment of MRI findings in myositis to provide defined outcome measures for use in clinical trials.