Noninvasive longitudinal assessment of early-stage Duchenne muscular dystrophy: In vivo diaphragm imaging in mdx mice

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle degeneration, with respiratory muscle weakness significantly impacting patient outcomes. Early detection of disease progression is critical for evaluating treatment strategies. This study investigates the feasibility of ultrasound shear wave elasticity imaging (US-SWEI) for assessing early-stage respiratory muscle changes in mdx mice, a model for DMD, aged 3 to 6 months. Longitudinal in vivo imaging evaluated the diaphragm's viscoelastic properties, with group and phase velocities measured to capture biomechanical changes. In mdx mice, group velocity increased from 3.47±0.15to4.20±0.20m/s, whereas wild-type values changed only modestly (2.76±0.11to3.01±0.16m/s). Histological analysis confirmed a significant positive correlation between group velocity and collagen deposition (R²=0.54,P=0.025), supporting fibrosis as a primary factor driving changes in diaphragm viscoelastic properties. These findings establish US-SWEI as a noninvasive, feasible approach for monitoring respiratory muscle health and advancing preclinical DMD research. By identifying early-stage changes in diaphragm properties, this approach enables the development of therapeutic interventions targeting respiratory complications. Furthermore, US-SWEI presents a potential avenue for assessing and monitoring neuromuscular diseases.