By combining metabolic markers with receptor binding, perfusion and neurotransmitter release, the availability of magnetic resonance-positron emission tomography (MR-PET) brain scanning opens up a wide range of possible research applications. Different tracers can be used to elucidate the involvement of synaptic function in special tasks in transmitters, receptors, and enzymes, and also to uncover changes caused by diseases and drugs. One of the greatest potential research areas to benefit from the simultaneous hybrid approach lies in pharmacological challenges with substances like nicotine or ketamine. The diagnostic advantages afforded by MRI and PET procedures may also turn MR-PET into the modality of choice for questions directed towards a deeper understanding of brain pathologies leading to neurodegeneration. Furthermore, in the field of neuro-oncology, the combination of metabolic and morphological imaging in hybrid MR-PET systems can potentially facilitate further insight into the biology of brain tumours. By being able to provide images that differentiate different types of tissue, the differential diagnosis of brain tumours can be improved. This, in turn, leads to improvements in treatment monitoring, the early identification of tumour progression and a more reliable identification of treatment-related tissue alterations.