The present invention relates to a medical instrument for automatically detecting affected regions in an examination area of a subject comprising: a memory containing machine executable instructions； and a processor for controlling the medical instrument, wherein execution of the machine executable instructions causes the processor to control the instrument to: obtain a first anatomical image of the examination area and a first image of fibers of the examination area, wherein a first parameter and a second parameter describe characteristics of the first anatomical image and the first image of fibers respectively； segment the first anatomical image into a plurality of segments indicating respective tissues and/or structures in the examination area； identify first lesions in the segmented first anatomical image； use values of the first and/or second parameters for determining seed points in the identified first lesions for a tracking algorithm for tracking first fibers in the first image of fibers.
