A medical data processing method of determining information describing the probable position of a neural fibre in a patient's brain, the method comprising the following steps which are constituted to be executed by a computer: a) acquiring patient-specific medical image data describing the brain of the patient; b) acquiring atlas data defining an image-based model of a human brain; c) determining, based on the patient-specific medical image data and the atlas data, seed region data describing seed regions (A, B) in the patient-specific medical image data in which the ends of neural fibres of the patient's brain may be located, wherein the seed region data is determined by determining a transformation between the atlas data and the patient-specific medical image data, and determining the position of white brain matter in the patient-specific medical image data based on the transformation, wherein the seed regions are at least two spatially disjunct and individually coherent seed regions (A, B) and are constituted by white brain matter; d) determining, based on the patient-specific medical image data and the seed region data, neural fibre tract data describing a plurality of potential tracts (T 1 , T 2 , T 3 ) which a specific neural fibre may take through the patient's brain; e) determining, based on the atlas data and the neural fibre tract data, a figure of merit for each one of the potential tracts (T 1 , T 2 , T 3 ), characterized in that the positions of a plurality of spatially disjunct and individually coherent regions of white brain matter are determined in the patient-specific medical image data based on the transformation, and wherein the coherent regions of white brain matter are sorted according to a probability of the respective model neural fibre tracts to contain fibre crossings, and wherein regions of white brain matter having a high priority in the sorting are selected as the seed regions (A, B) for determining the neural fibre tract data. a) acquiring patient-specific medical image data describing the brain of the patient; b) acquiring atlas data defining an image-based model of a human brain; c) determining, based on the patient-specific medical image data and the atlas data, seed region data describing seed regions (A, B) in the patient-specific medical image data in which the ends of neural fibres of the patient's brain may be located, wherein the seed region data is determined by determining a transformation between the atlas data and the patient-specific medical image data, and determining the position of white brain matter in the patient-specific medical image data based on the transformation, wherein the seed regions are at least two spatially disjunct and individually coherent seed regions (A, B) and are constituted by white brain matter; d) determining, based on the patient-specific medical image data and the seed region data, neural fibre tract data describing a plurality of potential tracts (T 1 , T 2 , T 3 ) which a specific neural fibre may take through the patient's brain; e) determining, based on the atlas data and the neural fibre tract data, a figure of merit for each one of the potential tracts (T 1 , T 2 , T 3 ), <EOS>