Anna Varentsova BS, Presenter: Nothing to Disclose

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

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

 The purpose of this study was to produce a human brain High Angular Resolution Diffusion Imaging (HARDI) template by combining information from artifact-free low angular resolution datasets collected on 67 subjects.

Turboprop diffusion-weighted (DW) (12 directions, b=900s/mm2, 67 subjects) and non-DW data were acquired on a 3T MRI scanner. Diffusion tensors from all subjects were registered to a single subject’s data (already transformed to ICBM152 space) using deformable registration with explicit orientation optimization (DTI-TK, PICSL, PA). Resulting transformations were applied to the DW and non-DW data of corresponding subjects. Due to the difference in spatial transformations, each voxel in ICBM-152 space eventually contained DW signals for 804 (67 subjects × 12 DW signals) unique diffusion directions. DW signals were fitted with a spherical harmonics (SH) series by a least squares minimization with Laplace-Beltrami regularization used to enhance smoothness of the function. Calculated SH series coefficients were used to recover orientation distribution functions (ODF) in a modified SH basis.

The figure shows an ODF map containing regions with single, as well as multiple fiber directions.

This work produced a HARDI template of the human brain. Intravoxel fiber crossings have been resolved and the information contained in the template is in agreement with underlying fiber anatomy of the brain.

The HARDI template may be used for the development of a detailed brain atlas, or as a reference in comparisons of the microstructural integrity of the brain across populations.

Varentsova, A, Zhang, S, Arfanakis, K, A Template of the Micro-Architecture of the Human Brain.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11010391.html