Time-efficient coronal MRI reflects clinical and pathological features of myopathies.

Traditional axial view-based skeletal muscle MRI is valuable for detecting pathological changes but is time-consuming. This study validated a novel time-efficient coronal view-based muscle MRI protocol and a semiquantitative visual scoring system as a practical alternative for evaluating hereditary (HM) and inflammatory myopathies (IM). Using coronal short tau inversion recovery (STIR) and T1-weighted sequences, we assessed edema and fatty infiltration in 102 subjects, including patients with HM, IM, and healthy controls. To verify diagnostic reliability, a plane-to-plane comparison (coronal vs. axial) was performed in the thigh muscles, demonstrating excellent agreement between visual scores (ICC > 0.9, Kappa > 0.79). Clinically, higher visual fat scores in HM correlated significantly with muscle weakness (p < 0.001) and older age, while higher edema scores in IM correlated with weakness (p = 0.013) and female sex. Histopathologically, MRI fat scores correlated with internal nucleation and Oil Red O staining (p < 0.001), whereas edema scores correlated with fiber necrosis (p < 0.001), regeneration, and interstitial fibrosis (p < 0.001). This novel coronal protocol offers a validated, high-throughput alternative enabling wide anatomical coverage in significantly less time, with visual scores that strongly correlate with clinical status and histopathology, supporting its utility as a biomarker for disease monitoring.