title: Evaluation of a silicon photomultiplier PET insert for simultaneous PET and MR imaging.
abstract: OBJECTIVE
  In this study, the authors present a silicon photomultiplier (SiPM)-based positron emission tomography (PET) insert dedicated to small animal imaging with high system performance and robustness to temperature change.
  
  
  METHODS
  The insert consists of 64 LYSO-SiPM detector blocks arranged in 4 rings of 16 detector blocks to yield a ring diameter of 64 mm and axial field of view of 55 mm. Each detector block consists of a 9 × 9 array of LYSO crystals (1.2 × 1.2 × 10 mm(3)) and a monolithic 4 × 4 SiPM array. The temperature of each monolithic SiPM is monitored, and the proper bias voltage is applied according to the temperature reading in real time to maintain uniform performance. The performance of this PET insert was characterized using National Electrical Manufacturers Association NU 4-2008 standards, and its feasibility was evaluated through in vivo mouse imaging studies.
  
  
  RESULTS
  The PET insert had a peak sensitivity of 3.4% and volumetric spatial resolutions of 1.92 (filtered back projection) and 0.53 (ordered subset expectation maximization) mm(3) at center. The peak noise equivalent count rate and scatter fraction were 42.4 kcps at 15.08 MBq and 16.5%, respectively. By applying the real-time bias voltage adjustment, an energy resolution of 14.2% ± 0.3% was maintained and the count rate varied ≤1.2%, despite severe temperature changes (10-30 °C). The mouse imaging studies demonstrate that this PET insert can produce high-quality images useful for imaging studies on the small animals.
  
  
  CONCLUSIONS
  The developed MR-compatible PET insert is designed for insertion into a narrow-bore magnetic resonance imaging scanner, and it provides excellent imaging performance for PET/MR preclinical studies.
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea and Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Guen Bae
authors.initials: GB
authors.lastname: Ko
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea and Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Kyeong Yun
authors.initials: KY
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea and Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Hyun Suk
authors.initials: HS
authors.lastname: Yoon
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea and Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Min Sun
authors.initials: MS
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea and Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Jeong-Whan
authors.initials: JW
authors.lastname: Son
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Hyung-Jun
authors.initials: HJ
authors.lastname: Im
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-799, South Korea; Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea; Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799, South Korea; and Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Lee
mesh_terms: D000818:Animals; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D051379:Mice; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D012825:Silicon; D013696:Temperature; D013997:Time Factors; D014618:Vacuum
chemical_list: D012825:Silicon