PT - JOURNAL ARTICLE AU - Jiguo Liu AU - Qiong Liu AU - Jyh-Cheng Chen AU - Deguang Wang TI - A Prototype Ultra-High-Resolution Small-Animal PET System DP - 2021 May 01 TA - Journal of Nuclear Medicine PG - 184--184 VI - 62 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/62/supplement_1/184.short 4100 - http://jnm.snmjournals.org/content/62/supplement_1/184.full SO - J Nucl Med2021 May 01; 62 AB - 184Objectives: We developed a high-resolution small-animal PET system based on silicon photomultiplier (SiPM) and lutetium yttrium orthosilicate (LYSO). In this work, we demonstrated the design of this system and the minimum identifiable resolution of the micro Derenzo phantom. Methods: The PET system consists of 24 detector boxes arranged in 3 continuous octagonal rings with a 90.418 mm axial length and a 129 mm scanner ring diameter. One single detector box contains two crystal modules formed by 4 (2 × 2) crystal arrays of 16 × 16 lutetium yttrium orthosilicate scintillation (LYSO) crystals (0.709 × 0.709 × 9 mm3 each crystal). The crystal array containing the enhanced specular reflector (ESR) optical reflective film inside placed on the 2 × 2 SiPM, and the center distance of the crystal is 0.794 mm. A 22Na (0.25 mm diameter sphere globe) point source with an activity of 1.221MBq was placed at the field of view (FOV) and scanned for 20 minutes to measure the energy resolution of the system. A micro Derenzo phantom, which has rod diameters of 0.5, 0.55, 0.6, 0.65, 0.7, and 0.75 mm and the center-to-center distance between adjacent rods is twice the rod diameter, was injected with 3.478MBq fluorine (18F)-fluorodeoxyglucose (FDG) and scanned for 30 minutes. The list-mode data were reconstructed using 3D-OSEM (8 subsets, 4 iterations, matrix-size: 105 × 105 × 111, pixel-size: 0.236 mm, reconstruction ring diameter of 25 mm, reconstruction axial length of 26 mm) to evaluate the spatial resolution of the system. In vivo PET imaging studies of brain, heart, and kidney were also conducted in the healthy mice using 18F-FGD to evaluate the imaging capability of the PET system. Results: The average energy resolution at 511-keV of the entire PET system was 22%. At a 360-660 keV energy window, the 0.5 mm rods of the micro Derenzo phantom were clearly identifiable using 3D-OSEM algorithm. In animal studies, we can clearly observe the brain structure, heart and kidney of the mice. Conclusions: The results show that the PET system has the characteristics of ultra-high-resolution and is very suitable for imaging of small rodent tissues and organs. Acknowledgement: This work was supported by Shandong Province Major Science and Technological Innovation Project (Grant No.2019JZZY021003). We acknowledge the contributions of all team members from Shandong Madic Technology Co., Ltd. Supporting data Figure 1 Picture of small-animal PET system Figure 2 Picture of a single crystal array of 16 × 16 LYSO crystals (a) (b) Figure 3 Physical picture of the micro Derenzo phantom (a) and transverse image reconstructed using 3D-OSEM algorithm (b). The size of the rods from small to large are 0.5, 0.55, 0.6, 0.65, 0.7, and 0.75 mm. The center-to-center distance between adjacent rods is twice the rod diameter. Figure 4 PET image of the healthy mouse brain