TY - JOUR T1 - Performance of a PET Insert for High-Resolution Small-Animal PET/MRI at 7 Tesla JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 536 LP - 542 DO - 10.2967/jnumed.116.187666 VL - 59 IS - 3 AU - Greg Stortz AU - Jonathan D. Thiessen AU - Daryl Bishop AU - Muhammad Salman Khan AU - Piotr Kozlowski AU - Fabrice Retière AU - Graham Schellenberg AU - Ehsan Shams AU - Xuezhu Zhang AU - Christopher J. Thompson AU - Andrew L. Goertzen AU - Vesna Sossi Y1 - 2018/03/01 UR - http://jnm.snmjournals.org/content/59/3/536.abstract N2 - We characterize a compact MR-compatible PET insert for simultaneous preclinical PET/MRI. Although specifically designed with the strict size constraint to fit inside the 114-mm inner diameter of the BGA-12S gradient coil used in the BioSpec 70/20 and 94/20 series of small-animal MRI systems, the insert can easily be installed in any appropriate MRI scanner or used as a stand-alone PET system. Methods: The insert consists of a ring of 16 detector-blocks each made from depth-of-interaction–capable dual-layer-offset arrays of cerium-doped lutetium-yttrium oxyorthosilicate crystals read out by silicon photomultiplier arrays. Scintillator crystal arrays are made from 22 × 10 and 21 × 9 crystals in the bottom and top layers, respectively, with respective layer thicknesses of 6 and 4 mm, arranged with a 1.27-mm pitch, resulting in a useable field of view 28 mm long and about 55 mm wide. Results: Spatial resolution ranged from 1.17 to 1.86 mm full width at half maximum in the radial direction from a radial offset of 0–15 mm. With a 300- to 800-keV energy window, peak sensitivity was 2.2% and noise-equivalent count rate from a mouse-sized phantom at 3.7 MBq was 11.1 kcps and peaked at 20.8 kcps at 14.5 MBq. Phantom imaging showed that features as small as 0.7 mm could be resolved. 18F-FDG PET/MR images of mouse and rat brains showed no signs of intermodality interference and could excellently resolve substructures within the brain. Conclusion: Because of excellent spatial resolvability and lack of intermodality interference, this PET insert will serve as a useful tool for preclinical PET/MR. ER -