System for simultaneous pet/mr imaging

Abstract

A combined PET/MR system includes an MR subsystem including a main field magnet () which generates a stationary magnetic field through an examination region (), a gradient magnetic field system () which applies magnetic field gradients across the examination region, and an RF system () that applies RF excitation pulses to excite resonance in a subject in the examination region and receive magnetic resonance signals from the subject. A PET detector module () which is permanently or removably fixed in the examination region () to detect radiation from radiopharmaceuticals injected into the subject causes distortions in the magnetic field gradients. A plurality of probes () which are mounted in a fixed relationship to the PET detector module () measure magnetic field strength. A gradient magnetic field distortion correction system () determines distortions caused in the gradient magnetic fields and corrects the magnetic resonance signals accordingly. The PET detector module includes a plurality of RF shielded detector units () which are mounted in a circumferentially spaced relationship with a gap () there between through which RF excitation pulses and magnetic resonance signals pass.