1. A method, comprising: generating, from data obtained by diffusion MRI imaging of a subject of interest, a plurality of streamtubes representing white matter fibers in at least one tract of interest (TOI) in a brain image of the subject of interest; determining a set of quantitative tractography metrics based on the generated streamtubes, the set comprising a plurality of members at least some of which are indicative of streamtube length; and comparing at least some members of the determined set of quantitative tractography metrics to a reference set of quantitative tractography metrics obtained from at least one reference subject to characterize the at least one TOI, where the at least one reference subject comprises one of the subject of interest, at least one reference subject known to have a certain white matter impairment and at least one reference subject not known to have a certain white matter impairment.