Analysis of Changes in Quantitative MRI with Time in Muscle Denervation of the Lower Extremities

Motivation: Quantitative muscle MRI (qMRI) metrics (T2, diffusion diameter, and fat fraction (FF)) are sensitive to tissue microstructure, and altered in denervated muscle. However, the time-dependencies of these metrics as they relate to denervated muscle have not yet been analyzed in humans. Goal(s): Assess patterns of qMRI changes in the lower extremity in denervated muscle. Approach: Muscles from 24 lower extremity exams (23 patients) were categorized as non-denervated or denervated (chronically- or acutely-involved) using electromyography findings. Results: Increased T2 in denervated muscles, and increased FF in chronically-involved muscles, and alternating patterns of diffusion diameter with time. Impact: Quantitative MRI changes in lower extremity denervated muscles may complement peripheral nerve MRI and electromyography by providing tissue sensitive information relevant to the extent of disease at specific timepoints from initial injury.