Comparison of Measures of Axonal Loss in Diffusion Models in Healthy Controls and Patients with Multiple Sclerosis at 3T

Motivation: Multiple sclerosis (MS) is a neurodegenerative disease with gaps in brain and spinal cord (SC) imaging necessitating advanced diffusion techniques to capture MS pathology. Goal(s): We sought to quantify axonal loss and understand the sensitivity of volume fraction measures to characterize MS microstructural changes. Approach: We comprehensively imaged the brain and cervical SC and applied measures from diffusion models in gray matter (GM), white matter (WM), and lesions in patients with relapsing-remitting MS (pwRRMS) and healthy controls (HCs). Results: We reveal significantly reduced volume fraction indices in MS lesions compared to HC WM and significant correlations between pwRRMS lesion indices and lesion volume. Impact: Volume fraction measures from novel diffusion models are sensitive to disease pathology in brain and spinal cord lesions of patients with multiple sclerosis, providing evidence of the utility of specific diffusion measures to capture axonal loss.