DEVELOPMENT OF A PET DETECTOR SYSTEM COMPATIBLE WITH MRI NMR SYSTEMS/

We report the development of a prototype positron emission tomography (PET) scanner compatible with clinical magnetic resonance imaging (MRI ) scanners and nuclear magnetic resonance (NMR) spectrometers. This si ngle slice PET system consists of 72 2x2x5 mm lutetium oxyorthosilicat e (LSO) crystals coupled by 2 mm diameter, 4 meter long double clad op tical fibers to three multi-channel photomultiplier tubes (MC-PMT's) s hielded inside an aluminum closure. The ring diameter is 54 mm and the slice thickness is similar to 1 mm FWHM. Measurements with a point so urce demonstrate that this PET system has a reconstructed resolution o f 2.1 mm, a coincidence time resolution of 26 ns and a typical energy resolution of 45%. Simultaneously acquired PET and MR phantom images s how no significant artifacts or distortions. We also obtained simultan eous NMR spectra and PET images from an isolated, perfused rat heart, demonstrating the power of obtaining temporally correlated PET and NMR information in biological systems. Again, no artifacts in the PET or NMR data were apparent, despite the high field strength of 9.4T. The c hallenge for the future is to scale up the design to develop a high re solution, high sensitivity device that can be used in simultaneous PET and MR studies of in vivo systems.