Integrated PET and MRI Scanners

Multimodality studies have become increasingly important for both clinical and preclinical imaging in recent years. This resulted in the development of hyphenated scanners, notably PET/CT (positron emission tomography-computed tomography), which is now the standard for PET imaging studies. The principal difficulty of combining PET and MR (magnetic resonance) is that standard photomultiplier tube (PMT)-based PET detectors do not function in significant magnetic fields; hence, either different detectors or some means of shielding the PMTs is required. After some 20 years of instrumentation development, mostly in the preclinical research environment, combined PET/MR systems have emerged and here we review the present status of this field. Keywords: PET/ MR; imaging; multimodality; photomultiplier; SiPM; APD