A radio frequency (RF) body coil assembly includes a coil support structure including an inner tubular member, an outer tubular member disposed radially outwardly from the inner tubular member, and a structural material disposed between the inner and outer tubular members, an RF coil mounted to an inner surface of the coil support structure, and a positron emission tomography (PET) detector assembly mounted to an outer surface of the coil support structure. A dual-modality imaging system is also described.