OBJECTIVES: To determine whether magnetic resonance imaging (MRI) findings reflect the pathological features of inflammatory myopathies. METHODS: Patients with idiopathic inflammatory myopathies (IIMs) diagnosed using the 2017 European League Against Rheumatism/American College of Rheumatology classification criteria in our university between 2005 and 2020 were retrospectively reviewed. IIMs were subclassified into the anti-aminoacyl transfer RNA synthetase syndrome [anti-synthetase syndrome (ASSD)], immune-mediated necrotizing myositis, dermatomyositis (DM), and others. Fat-suppressed T2-weighted MRI and muscle biopsy specimens were assessed in IIMs followed by the comparison among the four subgroups. RESULTS: MRI findings were available for 62 patients and histopathological findings were available for 27 patients. Perifascicular atrophy or necrosis in the muscle tissues from the patients with IIM was more frequently observed in patients with subcutaneous and fascial high signal intensity (HSI) on MRI than those without. Four-group comparison among ASSD, immune-mediated necrotizing myositis, DM, and others revealed that HSI in fasciae on MRI was more frequently observed in patients with ASSD and DM than in others. Perifascicular atrophy or necrosis in muscle tissues was more frequently observed in patients with ASSD than in others. CONCLUSION: Patients with ASSD had distinct MRI features compared with anti-aminoacyl transfer RNA synthetase negative patients. The fascial HSI on MRI may reflect distinctive pathological features of muscles.