National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran TANAFFOS (Respiration) 1735-0344 16 2 2017 06 01 Impact of Time-of-Flight and Point-Spread-Function for Respiratory Artifact Reduction in PET/CT Imaging: Focus on Standardized Uptake Value 127 135 240179 EN Roya Sharifpour Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran, Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran Pardis Ghafarian Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran PET/CT and Cyclotron Center, Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran, Mehrdad Bakhshayesh-Karam Pediatric Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran. Hamidreza Jamaati Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran, Mohammad Reza Ay Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran, Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran Journal Article 2020 12 24 Background: The most important advantage of positron emission tomography/computed tomography (PET/CT) imaging is its capability of quantitative analysis. The aim of the current study was to choose the proper standardized uptake value (SUV) threshold, when the time-of-flight (TOF) and point spread function (PSF) were used for respiratory artifact reduction in the liver dome in a new-generation PET/CT scanner. Materials and Methods: The current study was conducted using a National Electrical Manufacturers Association International Electrotechnical Commission body phantom, with activity ratios of 2:1 and 4:1. A total of 27 patients, with respiratory artifacts in the thorax region, were analyzed. PET images were retrospectively reconstructed using either a high definition (HD) + PSF (i.e., a routine protocol) algorithm or HD+PSF+TOF (PSF+TOF; i.e., to reduce the respiratory artifact) algorithms, with various reconstruction parameters. The SUVmax and SUVmean, at different thresholds (i.e., at 45%, 50%, and 75%), were also assessed. Results: Although in comparison to the routine protocol a higher SUV was observed when using the PSF+TOF method, this approach was used to reduce the respiratory artifact. The appropriate threshold for SUV was strongly related to the lesion size, reconstruction parameters, and activity ratio. The mean of the relative difference between PSF+TOF algorithm and routine protocol for SUVmax varied from 10.58±14.99% up to 35.49±32.60% (which was dependent on reconstruction parameters). Conclusion: In comparison with other types of SUVs, the SUVmax value illustrated its significant overestimation, especially at the 4:1 activity ratio. The poor agreement between SUVmax and SUV50% was also observed. When the TOF and PSF are utilized to reduce respiratory artifacts, the SUV50% can be an accurate semi-quantitative parameter for PET/CT images, for all lesion sizes. For smaller lesions, however, a smaller filter size was required to observe an accurate SUV. https://www.tanaffosjournal.ir/article_240179_61524b9940390996a2f6684a52b2fabd.pdf