A PET-MR apparatus is provided. The PET-MR apparatus may include a first supporting component, a PET detector, a second supporting component, and a radio frequency (RF) coil. The first supporting component may have an inner surface and an outer surface. The PET detector may be supported on the outer surface of the first supporting component. The second supporting component may be at least partially surrounded by the first supporting component. The RF coil configured to generate or receive an RF signal may be supported on the second supporting component.
