A medical image data processing system, the medical image data processing system comprising: - a memory storing machine executable instructions and a machine learning framework trained to receive an image intensity and an anatomical position of a voxel as an input and to provide a tissue type classification of the voxel in response as an output, - a processor for controlling the medical image data processing system, wherein execution of the machine executable instructions by the processor causes the processor to control the medical image data processing system to: - receive medical image data comprising an anatomical structure of interest, - fit an anatomical frame of reference (302, 402) to the medical image data using model-based segmentation, wherein a model used for the model-based segmentation comprises an anatomical reference structure in a reference space defined by the anatomical frame of reference (302, 402), wherein the fitting of the anatomical frame of reference (302, 402) comprises deforming the respective frame together with the anatomical reference structure to align the deformed anatomical reference structure (312, 412) with the anatomical structure of interest, wherein the fitting of the anatomical frame of reference provides anatomical positions relative to the deformed anatomical reference structure (312, 412), - classify tissue types represented by voxels of the medical image data using the machine learning framework, wherein each voxel comprises an image intensity and wherein image intensity and the anatomical positions of the voxels with respect to the deformed anatomical reference structure (312, 412) are used as the input to the machine learning framework. - a memory storing machine executable instructions and a machine learning framework trained to receive an image intensity and an anatomical position of a voxel as an input and to provide a tissue type classification of the voxel in response as an output, - a processor for controlling the medical image data processing system, wherein execution of the machine executable instructions by the processor causes the processor to control the medical image data processing system to: - receive medical image data comprising an anatomical structure of interest, - fit an anatomical frame of reference (302, 402) to the medical image data using model-based segmentation, wherein a model used for the model-based segmentation comprises an anatomical reference structure in a reference space defined by the anatomical frame of reference (302, 402), wherein the fitting of the anatomical frame of reference (302, 402) comprises deforming the respective frame together with the anatomical reference structure to align the deformed anatomical reference structure (312, 412) with the anatomical structure of interest, wherein the fitting of the anatomical frame of reference provides anatomical positions relative to the deformed anatomical reference structure (312, 412), - classify tissue types represented by voxels of the medical image data using the machine learning framework, wherein each voxel comprises an image intensity and wherein image intensity and the anatomical positions of the voxels with respect to the deformed anatomical reference structure (312, 412) are used as the input to the machine learning framework. - receive medical image data comprising an anatomical structure of interest, - fit an anatomical frame of reference (302, 402) to the medical image data using model-based segmentation, wherein a model used for the model-based segmentation comprises an anatomical reference structure in a reference space defined by the anatomical frame of reference (302, 402), wherein the fitting of the anatomical frame of reference (302, 402) comprises deforming the respective frame together with the anatomical reference structure to align the deformed anatomical reference structure (312, 412) with the anatomical structure of interest, wherein the fitting of the anatomical frame of reference provides anatomical positions relative to the deformed anatomical reference structure (312, 412), - classify tissue types represented by voxels of the medical image data using the machine learning framework, wherein each voxel comprises an image intensity and wherein image intensity and the anatomical positions of the voxels with respect to the deformed anatomical reference structure (312, 412) are used as the input to the machine learning framework.