Determination of Fiber Direction in High Angular Resolution Diffusion Images using Spherical Harmonics Functions and Wiener Filter

Diffusion tensor imaging (DTI) MRI is a noninvasive imaging method of the cerebral tissues whosefibers directions are not evaluated correctly in the regions of the crossing fibers. For the same reason,the high angular resolution diffusion images (HARDI) are used for estimation of the fiber direction ineach voxel. One of the main methods to specify the direction of fibers is usage of the sphericaldeconvolution. The spherical deconvolution is a method which is very sensitive to noise and createsnegative values in the orientation distribution function (ODF) of the fiber. To solve this problem,methods such as Laplace-Beltrami regularized spherical deconvolution (LB-SD), the gradient basedspherical deconvolution (GB-SD) and the constrained spherical deconvolution (CSD) are used. In thispaper, the method for SD based on Wiener filter (WB-SD) is presented. Regarding the results, thedirection of the crossing fibers is specified correctly. The proposed algorithm has specified thedirection of the fibers as zero degree with 4.9 standard deviation and 89.9 degree with 3.6 standarddeviation against two crossing fibers with 90 degree angle.