RESEARCH ARTICLE Decoding Diffusivity in Multiple Sclerosis: Analysis of Optic Radiation Lesional and Non-

Objectives Diffusion tensor imaging (DTI) has been suggested as a new promising tool in MS that may provide greater pathological specificity than conventional MRI, helping, therefore, to eluci-date disease pathogenesis and monitor therapeutic efficacy. However, the pathological substrates that underpin alterations in brain tissue diffusivity are not yet fully delineated. Tract-specific DTI analysis has previously been proposed in an attempt to alleviate this problem. Here, we extended this approach by segmenting a single tract into areas bound by seemingly similar pathological processes, which may better delineate the potential associa-tion between DTI metrics and underlying tissue damage. Method Several compartments were segmented in optic radiation (OR) of 50 relapsing-remitting MS patients including T2 lesions, proximal and distal parts of fibers transected by lesion and fi-bers with no discernable pathology throughout the entire length of the OR. Result