Whole-Tract Reduction in Fractional Anisotropy in the Corticospinal Tracts of Amyotrophic Lateral Sclerosis Patients, as Measured Using a Weighted 3-D Region of Interest in Template Space After Deformable Diffusion Tensor Imaging Registration

John H. Woo¹, Elias R. Melhem¹, Sumei Wang¹, Lauren Elman², Leo McCluskey², Lisa Desiderio¹, Hui Zhang¹, James Gee¹

Amyotrophic lateral sclerosis (ALS) is a degenerative disease of motor neurons. Using diffusion tensor imaging, previous investigators have measured a reduction in fractional anisotropy (FA) in the corticospinal tract, thought to reflect axonal degeneration. However, these methods often required manual segmentation or individual fiber tractography to generate regions-of-interest (ROI). In this study, we performed whole-tract FA measurements using a deformable tensor-driven registration algorithm and a weighted 3D ROI of the CST in template space. We found a highly significant difference between 12 ALS patients and 7 controls. This method may be especially useful for evaluating whole-tract differences in large groups.