Characterization of neurite and soma organization in the in vivo spinal cord with diffusion MRI

Motivation: Multicompartment models of diffusion MRI have proven valuable in the brain. Goal(s): However, application of these models in the spinal cord (SC) remains relatively understudied. Approach: Here, we address challenges related to acquisition and image processing in order to apply the Soma and Neurite Density Imaging (SANDI) model in the human SC in 11 healthy subjects. Results: We show that SANDI captures differences between white and gray matter tissue types and across the functionally relevant white matter pathways and gray matter architectures and has the potential to act as a biomarker for biomedical applications. Impact: We show that the Soma and Neurite Density Imaging (SANDI) diffusion model is a feasible method to characterize both white and gray matter tissue microstructure of the in vivo human spinal cord on clinical scanners.