Hong-Hsi Lee1, Jelle Veraart1,2, Dmitry S. Novikov1, and Els Fieremans1
1New York University, Center for Biomedical Imaging, New York, NY, United States, 2iMinds-Vision Lab, University of Antwerp, Antwerp, Belgium
Diffusion MRI enables to evaluate microstructure
at the mesoscopic scale. In particular, tuning the diffusion time over a wide
range could increase the sensitivity for acquiring useful biomarkers, such as
the axonal diameter or density. However, it is unclear whether either intra-,
or extra-axonal water attribute most to the observed changes of diffusion
signal with diffusion time. Here, we evaluate the dependence of the diffusion
coefficient (obtained from the diffusion signal at low $$$b$$$-value) on
$$$\delta$$$ and $$$\Delta$$$ in the direction perpendicular to axons in the
human brain, and explain these dependencies by diffusion of water in the
extra-axonal space.
