Improving the Realism of White Matter Numerical Phantoms: A Step toward a Better Understanding of the Influence of Structural Disorders in Diffusion MRI

Frontiers in Physics

Poupon, Fabrice¹  Estournet, Delphine¹  Axer, Markus¹  Matuschke, Felix²  Ginsburger, Ké³  Poupon, Cyril³  Mangin, Jean-Franç³  ois⁴  vin⁴  Beaujoin, Justine⁴ 

[1] Paris-Saclay, France;CEA DRF/ISVFJ/Neurospin/UNATI, France;CEA DRF/ISVFJ/Neurospin/UNIRS, France;Université

关键词: diffusion time-dependence;    white matter microstructure;    Trapezoidal OGSE sequences;    Axonal Diameter;    Monte-Carlo Simulations;    Biomimicking numerical phantoms;   

DOI  :  10.3389/fphy.2018.00012

学科分类：物理（综合）

来源: Frontiers

【 摘 要 】

White matter is composed of irregularly packed axons leading to a structural disorder in the extra-axonal space. Diffusion MRI experiments using oscillating gradient spin echo sequences have shown that the diffusivity transverse to axons in this extra-axonal space is dependent on the frequency of the employed sequence. In this study, we observe the same frequency-dependence using 3D simulations of the diffusion process in disordered media. We design a novel white matter numerical phantom generation algorithm which constructs biomimicking geometric configurations with few design parameters, and enables to control the level of disorder of the generated phantoms. The influence of various geometrical parameters present in white matter, such as global angular dispersion, tortuosity, presence of Ranvier nodes, beading, on the extra-cellular perpendicular diffusivity frequency dependence was investigated by simulating the diffusion process in numerical phantoms of increasing complexity and fitting the resulting simulated diffusion MR signal attenuation with an adequate analytical model designed for trapezoidal OGSE sequences. This work suggests that angular dispersion and especially beading have non-negligible effects on this extracellular diffusion metrics that may be measured using standard OGSE DW-MRI clinical protocols.

【 授权许可】

CC BY