TY - JOUR T1 - Impacts of improved TOF timing resolutions on cold contrast of PET images JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 3037 LP - 3037 VL - 62 IS - supplement 1 AU - Hideaki Sato AU - Suguru Katsube AU - Yuma Tsubaki AU - Kodai Kumamoto AU - Yuji Tsutsui AU - Kazuhiko Himuro AU - Shingo Baba AU - Masayuki Sasaki Y1 - 2021/05/01 UR - http://jnm.snmjournals.org/content/62/supplement_1/3037.abstract N2 - 3037Purpose: Time-of-flight (TOF) is the difference in the arrival time of the detectors between two annihilation photons and reduces the probability distribution that annihilation events occur along the line of response (LOR). Recently, the state-of-the-art positron emission tomography (PET)/computed tomography (CT) with significantly improved TOF timing resolution has been introduced at Kyushu University Hospital. An improved TOF is expected to reduce noise and to improve the lesion detectability. This study evaluated the impacts of improved TOF timing resolutions on the cold contrast of PET images.Materials and Method: The TOF timing resolutions on Biograph Vision and Biograph mCT (Siemens Healthineers) were 214 and 540 psec, respectively. The background of the NEMA IEC Body Phantom was filled with an 18F-FDG solution (Vision: 2.55 kBq/mL, mCT: 3.20 kBq/mL) including six cold spheres (37, 28, 22, 17, 13, and 10 mm diameter). The 3D list mode data were obtained in 30 min. Attenuation correction was performed, but scattered correction was not, and post filter was not applied. The image matrix was 440 × 440 and 400 × 400 in Vision and mCT, respectively. The PET data were reconstructed with ordered-subsets expectation maximization (OSEM), and OSEM + TOF. The PET images of mCT were reconstructed in OSEM (iteration 3, subset 24) and OSEM+TOF (iteration 2, subset 21). Those of Vision were reconstructed in OSEM (iteration 5, subset 5) and OSEM+TOF (iteration 3, subset 5). The image quality was assessed using the coefficient of variation of background (CVbackground) and the contrast-noise ratio of cold spheres (QC,10mm/N10mm, QC,37mm/N37mm). These categories were assessed using PMOD 3.8.Result: The CVbackground of mCT was 4.32% for OSEM + TOF, whereas that of Vision was 2.25% for OSEM + TOF. That of Vision was superior to that of mCT. The Q10mm/N10mm of mCT was 5.95% and 8.18% for OSEM and OSEM + TOF, respectively, whereas that of Vision was 6.40% and 10.10% for OSEM and OSEM + TOF, respectively. The results and improvement rates by TOF reconstruction of Vision were superior to those of mCT. The Q37mm/N37mm of mCT was 9.32% and 12.78% for OSEM and OSEM+TOF, respectively, whereas that of Vision was 14.29% and 25.00% for OSEM and OSEM + TOF, respectively. The results and improvement rates by TOF reconstruction of Vision were superior to those of mCT.Conclusion: A more superior image quality is obtained with a higher TOF timing resolution in background and cold contrast. ER -