A device is disclosed for superposed MRI and PET imaging and includes an MRI tube that has a first field of view along its longitudinal direction, and a multiplicity of PET detection units arranged opposite one another in pairs about the longitudinal direction. In at least one embodiment the many PET detection units define a second field of view along the longitudinal direction, and their arrangement density along the longitudinal direction is optimized such that the second field of view substantially corresponds to the first field of view.