Performance of Detector Modules for a Second-Generation RF-Penetrable Brain TOF-PET Insert for Simultaneous PET/MRI

Multimodality imaging is a very promising field. The tremendous success of integrating positron emission tomography (PET) with computed tomography (CT) has demonstrated the beneficial role it can play in clinical diagnosis. Compared to CT, MRI is similar in spatial resolution and offers better soft-tissue contrast, zero ionizing radiation exposure, simultaneous imaging with PET, and functional information with functional MRI (fMRI) and MR spectroscopy (MRS). Currently, clinical permanently-integrated PET/MRI systems are available. However, the high cost impedes the widespread availability of PET/MR imaging. An alternative approach is to develop a portable PET insert that leverages the existing MRI units and is thus more affordable than the commercial permanently-integrated PET/MRI solution. We are developing a cost-efficient RF-penetrable time of flight (TOF)-PET insert for simultaneous PET/MRI, which is portable, MR-compatible, and TOF-capable. In this paper, we evaluate the performance of two fully assembled detector modules comprising 128x6x2 LYSO crystal elements coupled to matching SiPMs for our RF-penetrable TOF-PET insert design. The global coincidence time resolution, energy resolution, coincidence count rate, and detector temperature achieved over 10 1-minute datasets were 238.0 ± 0.4 ps FWHM, 11.5 ± 0.02% FWHM, 25.1 ± 0.2 kcps, and 22.6 ± 1.0 ^◦ C, respectively. These results demonstrate the excellent ToF capability and the performance stability for a scalable detector module.