Free-Form Fibers: A Whole Brain Fiber-to-DTI Registration Method

We propose a novel whole brain fiber-to-DTI registration method and apply it to a clinical study of small vessel diseases. It deforms a manually annotated fiber model to diffusion tensor images of new subjects. Fiber trajectories and anatomically meaningful fiber bundles are automatically obtained by this registration. The free-form deformations are used to regularize the transformations at the whole brain level and across fiber bundles. Fiber curvatures are penalized as the intra-fiber regularization to encourage the smoothness of transformed fibers. A Laplace along-fiber regional prior learned from healthy subjects is proposed to evaluate the match between fibers and tensors in patients. It effectively improves the registration performance in the presence of white matter lesions. Experimental results show successful registration on 55 subjects and the DTI measurement computed from registered anatomical fiber bundles have significant correlation with cognitive functions.