A generally cylindrical set of coil windings (10, 30, 80) includes primary coil windings (12, 32, 82) and shield coil windings (14, 34, 84) at a larger radial position than the primary coil windings, and an arcuate or annular central gap (16, 36, 86) that is free of coil windings, has an axial extent (W) of at least ten centimeters, and spans at least a 180.degree. angular interval. Connecting conductors (24, 44, 94) disposed at each edge of the central gap electrically connect selected primary and secondary coil windings. In a scanner setting, a main magnet (62, 64) is disposed outside of the generally cylindrical set of coil windings. In a hybrid scanner setting, an annular ring of positron emission tomography (PET) detectors (66) is disposed in the central gap of the generally cylindrical set of coil windings.