Association Between MRI Features and Histopathology in Paraspinal Muscle Atrophy and Fiber Type Distribution in CLBP: A Cross-Sectional Study

Motivation: Limited access to muscle tissue restricts MRI studies on muscle atrophy and fiber type distribution in chronic low back pain (CLBP), highlighting a need for non-invasive methods. Goal(s): To correlate MRI features with markers of muscle atrophy and fiber type distribution in CLBP. Approach: We measured cross-sectional area (CSA) and diffusion-tensor imaging (DTI) metrics in the multifidus and erector spinae muscles, linking findings to atrophy and fiber composition. Results: Reduced CSA correlated with atrophy, especially in the multifidus. Higher fractional anisotropy and lower radial diffusivity were observed, with fractional anisotropy positively correlating with Type I fiber proportion. Impact: By demonstrating that both CSA and DTI metrics can non-invasively assess muscle atrophy and fiber type distribution, this study supports MRI's role in enhancing CLBP diagnosis and treatment, particularly in monitoring muscle degeneration and guiding therapy.