Michiel Cottaar1, Matteo Bastiani1, Charles Chen2, Krikor Dikranian2, David C. Van Essen2, Timothy E. Behrens1, Stamatios N. Sotiropoulos1, and Saad Jbabdi1
1FMRIB, Oxford University, Oxford, United Kingdom, 2Washington University School of Medicine, Saint Louis, MO, United States
Close to the cortical white/gray matter boundary surface fiber
orientations sharply transition from being nearly tangential to the surface in the
white matter to mostly radial in the gray matter. We propose a geometric model that
describes this transition at sub-voxel resolution based on high-resolution
histology data and fit this model to lower resolution diffusion MRI data. We
assess its performance using qualitative comparisons with histology and test
the reproducibility of the estimated parameters across multiple diffusion MRI
resolutions. This model allows the in-vivo estimation of fiber orientations
across the white/gray matter boundary, which may improve tracking to the
cortex.
