Quantitative Magnetic Resonance Imaging of Gluteal Muscle Groups Detects Stage‐Specific Progression and Early‐Stage Damage in Duchenne Muscular Dystrophy: A 12‐Month Longitudinal Study

ABSTRACT Introduction/Aims Quantitative MRI (qMRI) of gluteal muscle groups for Duchenne muscular dystrophy (DMD) progression requires sensitive biomarkers and stage‐specific validation. This 12‐month study investigates qMRI responsiveness across disease stages and identifies early‐stage damage markers. Methods A total of 137 DMD patients (9.1 ± 1.8 years) and 32 controls (9.5 ± 2.0 years) were prospectively enrolled and underwent 3 T MRI (T1 mapping, 3‐point Dixon) assessing fat fraction (FF) and T1 in gluteal muscle groups (flexors, extensors, adductors, and abductors). Patients underwent North Star Ambulatory Assessment (NSAA) and timed functional tests and were classified by baseline NSAA scores into mild (76–100), moderate (51–75), and severe (0–50) groups. Standardized response mean (SRM) was used as a measure of disease progression responsiveness. Results Over 12 months, the severe group showed greater T1 and FF changes (except adductors) than mild/moderate groups, while FF changes of the adductors were only higher than the mild group. The moderate group had greater FF changes than the mild group ( p < 0.05). qMRI responsiveness to disease progression varied by disease stage, with FF of the abductors in the mild functional stable/decline group ( SRM = 1.016/1.445) and adductors in moderate/severe groups ( SRM = 1.606/1.633) showing the highest responsiveness. SRM for function scales remained below 0.8 in all DMD subgroups. qMRI biomarkers demonstrated potential for identifying early‐stage patients with or without functional decline. Discussion qMRI of the gluteal muscle group demonstrates higher responsiveness to DMD progression than function scales, with sensitivity varying by disease stage. qMRI biomarkers appear to be useful for assessing subclinical progression detection.