TY - JOUR T1 - Quantitative differences of pancreatic lesions in cilinical simultaneous [18F]FDG PET/MR imaging:TOF versus non-TOF measurements JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1309 LP - 1309 VL - 58 IS - supplement 1 AU - Guilan Hu AU - Haiqun Xing AU - Tong Wang AU - Li Huo AU - Fang Li Y1 - 2017/05/01 UR - http://jnm.snmjournals.org/content/58/supplement_1/1309.abstract N2 - 1309Objectives: With the development of simultaneous PET/MR scanner, PET detector advanced from avalanche photodiodes to silicon photomultipliers (SiPMs); as a result, time-of-flight (TOF) became commercially available. One of the commonly known advantages of TOF is that it makes small lesion detectability improved depending on yielding a better signal to-noise ratio (SNR). TOF application results in quantitative measurements of standardized uptake value (SUV) differ from those with non-TOF PET images. These quantitative differences may be important in both clinical interpretation and multicenter clinical trials. The purpose of this study is to determine if and by how much SUV quantitatively of pancreatic tumors differs between TOF and non-TOF reconstructions in clinical simultaneous [18F]FDG PET/MR Imaging.Methods: 35 patients (13 females, 22 males median, 59.25±11.8 years old) with pancreatic tumors underwent simultaneous PET/MR (SIGNA, GE Healthcare, USA) scan 2-3h after injection. The injected dose of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) was 3.7-5.4MBq/kg body weight for patients. PET/MR scans in upper abdomen were all finished in 25-30min with arms down. List mode PET images were acquired simultaneously with MRI. Each PET list mode data was reconstructed with and without TOF respectively using the system default three-dimensional ordered subset expectation maximization iterative reconstruction algorithm (3D OSEM). T2 MRI was employed for lesion localization. Region of interests (ROI) were applied for SUVmax and SUVmean measurement in PET/MRI fusion images. TOF and non-TOF SUVs were assessed with paired t-test.Results: Both SUVmean and SUVmax of each pancreatic lesions in TOF images showed higher than those in non-TOF images. For all lesions, the average SUVmean increased by 6.2%, and the average SUVmax increased by18.3% on TOF reconstructions. Compared with non-TOF, smaller lesions (<2cm) SUVs (including SUVmean and SUVmax) in TOF increased more significant than those of larger one (>2cm). The increased percentage of small lesion SUVmean and SUVmax were 11.3% and 30.6% respectively, while the larger ones increased only 4.1% and 15.9%. These differences were with statistically significant. 22 of 35 patients were with pancreatic solid tumors, and the others were with cyst tumors. Compared with solid tumors, the increased percentage of cyst tumors SUVmean and SUVmax in TOF showed significant lower. SUVmean and SUVmax of cyst tumors increased only by 1.5% and 10.2%; while they increased by 7.9% and 30.0% in solid tumors respectively.Conclusion: The quantitative differences of pancreatic tumors are apparent in TOF vs. non-TOF PET/MRI images. Depending on greater quantitative effect from TOF reconstruction, simultaneously TOF PET/MRI will positively impact the early detection of small (<2cm) and solid pancreatic lesions and improve lesion quantification. Research Support: Peking Union Medical College Hospital ER -