Combined Diffusion-Relaxation MRI to Assess Muscle Microstructure and Composition

Motivation: Quantifying muscle tissue properties is crucial for understanding physio-pathological changes occurring in skeletal muscle (SM). However, current methods measure T2 and diffusion separately, and hence conflate them. Goal(s): Demonstrate a combined diffusion-relaxation MRI approach for disentangling T2 and diffusivity properties in SM. Approach: We devise and implement a combined T2-diffusion sequence in the leg muscles in five healthy volunteers after exercise. DTI and an advanced diffusion model were implemented and compared. Results: We calculated disentangled T2 and diffusion-related parameter maps. Our maps capture muscle tissue differences in specific muscle groups highlighting differences related to muscle involvement during exercise. Impact: Combined diffusion-relaxation MRI can provide detailed non-invasive estimation of muscle tissue properties by mitigating T2 effects on diffusion parameters. These approaches could reduce the need for invasive biopsies for evaluating muscle changes related to neuromuscular diseases, exercise, and rehabilitation.