A device is disclosed for superposed magnetic resonance and positron emission tomography imaging. In at least one embodiment the device includes a gradient coil and a positron emission tomography unit (PET unit). The PET unit is arranged within the gradient coil and has a first shield against radiofrequency radiation which in part surrounds the PET unit, and a second shield against radiofrequency radiation is arranged on the gradient coil. The first shield is connected to the second shield to form a shield which is at least partly closed. This makes a closed shield for the PET unit possible, which nevertheless is still easily accessible for maintenance purposes due to the two-part design of the shield.