A method is disclosed for evaluating a PET dataset with information concerning spatial distribution of a neurotransmitter and/or a neuromodulator in the brain of a patient wherein, in addition to the PET dataset, an especially morphometric magnetic resonance image dataset is recorded, which is or will be registered with the PET dataset. Concentration data of the spatial distribution is assigned to at least one specific region of the brain, especially to a nucleus, taking into account the magnetic resonance image data, for establishing result data assigned to the region.