Anna Varentsova BS, Presenter: Nothing to Disclose

Shengwei Zhang BS, BEng, Abstract Co-Author: Nothing to Disclose

Konstantinos Arfanakis PhD, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to develop a probabilistic atlas of gray matter (GM) connectivity through probabilistic white matter (WM) fiber tractography on an artifact-free high angular resolution diffusion-imaging (HARDI) template.

HARDI template: Turboprop DTI data were acquired on 72 human subjects using a 3T MRI scanner. Diffusion tensors from all subjects were transformed to ICBM152 space using deformable registration with explicit orientation optimization (DTI-TK, PICSL, PA). Resulting transformations were applied to the raw diffusion-weighted (DW) and non-DW data of corresponding subjects. Due to differences in spatial transformations, each voxel of the combined dataset contained DW signals for 864 unique diffusion directions. Fiber orientation distribution functions (FOD) were produced using constrained spherical deconvolution. Tractography: Probabilistic tractography was performed on the resulting HARDI template using MRtrix, with seeds placed at the WM-GM interface. Gray matter atlas: The raw T1-weighted data from all subjects were segmented into 42 cortical and subcortical GM regions per hemisphere using FreeSurfer. The GM labels from all subjects were then transformed to ICBM-152 space using the transformations generated above. Each GM voxel in ICBM-152 space was labeled with a multi-atlas approach using the transformed labels from all subjects and a vote-rule. HARDI template and GM atlas used in the study are parts of IIT Human Brain Atlas project (https://www.nitrc.org/projects/iit2). Connectivity: A two-ROI approach was used to segment tracts connecting each pair of 84 cortical and subcortical GM regions.

For each pair of GM labels, the generated atlas contains a map of the probability a WM voxel belongs to the connection of the two labels. The resulting maps of connectivity are in general agreement with known brain anatomy.

This work has generated a digital atlas of human brain GM connectivity based on probabilistic tractography on an artifact-free HARDI template.

The new atlas can be used for atlas-based segmentation in ROI studies, as a reference for spatial normalization in voxel-wise studies, as well as for labeling of voxel-wise findings.

Varentsova, A, Zhang, S, Arfanakis, K, Atlas of Human Brain Gray Matter Connectivity.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004262.html