An integrated magnetic resonance (MR) and positron emission tomography (PET) system includes an MR scanner including a magnet that defines an opening in which a subject is positioned, a set of PET detectors disposed between the magnet and the opening, and a plurality of data processing units, each data processing unit being configured for communication with a respective one or more of the PET detectors of the set of PET detectors. The plurality of data processing units are positioned along a side of the MR scanner not having the opening.