title: A framework to analyze cerebral mean diffusivity using surface guided diffusion mapping in diffusion tensor imaging.
abstract: The mean diffusivity (MD) value has been used to describe microstructural properties in Diffusion Tensor Imaging (DTI) in cortical gray matter (GM). Recently, researchers have applied a cortical surface generated from the T1-weighted volume. When the DTI data are analyzed using the cortical surface, it is important to assign an accurate MD value from the volume space to the vertex of the cortical surface, considering the anatomical correspondence between the DTI and the T1-weighted image. Previous studies usually sampled the MD value using the nearest-neighbor (NN) method or Linear method, even though there are geometric distortions in diffusion-weighted volumes. Here we introduce a Surface Guided Diffusion Mapping (SGDM) method to compensate for such geometric distortions. We compared our SGDM method with results using NN and Linear methods by investigating differences in the sampled MD value. We also projected the tissue classification results of non-diffusion-weighted volumes to the cortical midsurface. The CSF probability values provided by the SGDM method were lower than those produced by the NN and Linear methods. The MD values provided by the NN and Linear methods were significantly greater than those of the SGDM method in regions suffering from geometric distortion. These results indicate that the NN and Linear methods assigned the MD value in the CSF region to the cortical midsurface (GM region). Our results suggest that the SGDM method is an effective way to correct such mapping errors.
authors.affiliation: Department of Biomedical Engineering, Hanyang University Seoul, South Korea.
authors.forename: Oh-Hun
authors.initials: OH
authors.lastname: Kwon
authors.affiliation: School of Electronic and Electrical Engineering, Sungkyunkwan University Suwon, South Korea.
authors.forename: Hyunjin
authors.initials: H
authors.lastname: Park
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine Seoul, South Korea.
authors.forename: Sang-Won
authors.initials: SW
authors.lastname: Seo
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine Seoul, South Korea.
authors.forename: Duk L
authors.initials: DL
authors.lastname: Na
authors.affiliation: Department of Biomedical Engineering, Hanyang University Seoul, South Korea.
authors.forename: Jong-Min
authors.initials: JM
authors.lastname: Lee
keywords: cortical thickness; diffusion tensor imaging; geometric distortions; magnetic resonance imaging; mean diffusivity