Abstract #1357

The Effect of Axonal Beading on Water Diffusion Properties: a Monte Carlo Simulation of Axonal Degeneration and Its Effects on DTI Contrasts

Jonathan A.D. Farrell^1,2, Bennett A. Landman³, Jiangyang Zhang², Seth Smith^1,2, Daniel S. Reich^4,5, Peter A. Calabresi⁵, Peter C. van Zijl^1,2

¹F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; ²Neuroscience Section, Division of MR Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; ³Dept. of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; ⁴Division of Neuroradiology, Dept. of Radiology, Johns Hopkins University School of Mediciine, Baltimore, MD, USA; ⁵Dept. of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA

Axonal degeneration, due to injury or disease, can cause multiple localized dilations (beading) of the axonal membrane. The goal of this study was to determine the effect of these morphological changes on diffusion properties measured with DWI. Healthy axons are modeled as cylinders, and degenerating axons are modeled as the union of a cylinder and a sphere of varying radii. Using a Monte Carlo framework, we show that axonal beading can cause decreased, non-Gaussian parallel diffusion, and increased perpendicular diffusion. This may aid the interpretation of DWI experiments and advance the development of DTI contrasts specific for axonal injury.