Accurate Estimation of Intra-Axonal Water Diffusion Requires Proper Modeling of Surrounding Cellularityμμ

Yong Wang¹, Sheng-Kwei Song¹, ²

Diffusion MRI has been proposed to measure the intra-axonal water diffusion to more accurately reflect axonal integrity. Reasonable intra-axonal water fraction and axial diffusivity have been reported in normal healthy brains, suggesting potential application to patients with central nervous system (CNS) diseases. However, the confounding effect of cellularity surrounding the axons has not been adequately modeled in most of those methods. In this study, Monte Carlo simulation was employed to investigate the effect of varied cellularity surrounding the axons on the intra-axonal water diffusion measurement. Preliminary data suggested that proper modeling of cellularity component is critical to accurately estimate intra-axonal water diffusion, especially for CNS lesions with prominent cell infiltration.