MRI-derived 3D lower limb muscle shape as a biomarker for disease severity in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle degeneration leading to loss of ambulation. Identification of predictive biomarkers of loss of ambulation is crucial, yet analysis of muscle shape remains underexplored. Using MRI data from 17 children with DMD (10 followed by loss of ambulation) and 10 healthy controls, we analyzed the muscle shapes and volumes of the lower limbs. Correlations with functional metrics (gait tests, dynamometric forces) were evaluated, and exploratory predictive modeling tasks (classification and regression) were performed via random forests with cross-validation. Compared with controls, key muscle groups, particularly the triceps surae, in individuals with DMD presented distinct shape patterns, including increased thickness and reduced extensibility, without consistent differences in absolute volume. In cross-validated analyses and within the limits of this small cohort, models based on shape descriptors showed high accuracy for distinguishing controls from DMD and yielded a mean absolute error of approximately 110 days for time-to-ambulation-loss prediction. These findings suggest that geometric descriptors may provide complementary, acquisition-agnostic information to MRI fat-related measures, but require validation in larger, independent cohorts before any clinical use is considered. The results of this study highlight the potential of 3D muscle shape analysis as a non-invasive biomarker for disease severity in DMD. However, it is essential to note that this study was conducted on a small cohort and that further research is necessary to confirm these findings and establish the clinical utility of this approach. Laboratory peptides, such as those provided by our company, can be used to study the effects of muscle degeneration on muscle shape and volume. However, it is crucial to emphasize that these peptides are for research use only and should not be used for human subjects or any clinical application without proper authorization and regulatory compliance.