{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T03:40:11Z","timestamp":1773286811891,"version":"3.50.1"},"reference-count":34,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T00:00:00Z","timestamp":1773187200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Prostate Cancer Foundation Young Investigator Award"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Tomography"],"abstract":"<jats:p>Objectives: This study evaluated the test\u2013retest repeatability of semi-quantitative and volumetric features derived from artificial intelligence (AI)-assisted lesion segmentation on 18F-DCFPyL Prostate Specific Membrane Antigen (PSMA)-PET\/CT imaging of patients with prostate cancer (PCa). Specifically, we assessed the reliability of maximum, minimum and total standardized uptake values (SUVmax, SUVmean, SUVtotal) and lesion volume measurements across varying lesion sizes and explored the implications of variability for clinical decision-making. Methods: We analyzed 18F-DCFPyL PSMA-PET\/CT images from 22 patients with metastatic PCa. Lesion segmentation was performed using the AI-guided TRAQinform IQ technology, followed by a manual review to eliminate potential false-positive sites of uptake. Lesion-level test\u2013retest repeatability was evaluated using 95% limits of agreement (LOA), intra-class correlation coefficient (ICC), within-subject coefficient of variation (wCOV) and Bland\u2013Altman analysis for SUV and volumetric parameters. Lesions were stratified by size (&gt;1 cm3 and &gt;1.5 cm3) to assess the impact of lesion volume cut-offs on measurement variability. Results: A total of 297 lesions were analyzed, including 191 lesions &gt; 1 cm3 and 161 lesions &gt; 1.5 cm3. Test\u2013retest variability was higher in smaller lesions, with narrower LOA and lower wCOV for larger lesions. SUVmax and SUVmean exhibited lower variability than SUVtotal and lesion volume. The 95% LOA for SUVmax ranged from \u221233.81% to +38.02% for all lesions, improving to \u221231.82% to +31.01% for lesions &gt; 1.5 cm3. Similar trends were observed for SUVmean, SUVtotal, and volume. Bland\u2013Altman plots confirmed reduced variability in larger lesions, with no significant systematic bias. Conclusions: The test\u2013retest repeatability of AI-assisted PSMA-PET\/CT features varies by feature type, with semi-quantitative features demonstrating improved repeatability relative to volumetric features. Additionally, repeatability is influenced by lesion size, with larger lesions exhibiting greater reliability. These findings highlight the importance of lesion size-dependent thresholds in response assessment and variability-aware feature selection in prognostic models. Current algorithms may be better optimized for larger lesions and higher volumes of disease, with limitations remaining in the robust detection and segmentation of smaller\/more subtle lesions.<\/jats:p>","DOI":"10.3390\/tomography12030038","type":"journal-article","created":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T11:44:52Z","timestamp":1773229492000},"page":"38","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Repeatability of Semi-Quantitative and Volumetric Features from Artificial-Intelligence-Guided Lesion Segmentation on 18F-DCFPyL PSMA-PET\/CT Images: Results from a Test-Retest Cohort"],"prefix":"10.3390","volume":"12","author":[{"given":"Md Zobaer","family":"Islam","sequence":"first","affiliation":[{"name":"Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9906-5087","authenticated-orcid":false,"given":"Timothy G.","family":"Perk","sequence":"additional","affiliation":[{"name":"AIQ Solutions, Madison, WI 53717, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5230-7782","authenticated-orcid":false,"given":"Amy","family":"Weisman","sequence":"additional","affiliation":[{"name":"AIQ Solutions, Madison, WI 53717, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2780-5100","authenticated-orcid":false,"given":"Mark C.","family":"Markowski","sequence":"additional","affiliation":[{"name":"Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4138-2186","authenticated-orcid":false,"given":"Kenneth J.","family":"Pienta","sequence":"additional","affiliation":[{"name":"Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1621-6661","authenticated-orcid":false,"given":"Young E.","family":"Whang","sequence":"additional","affiliation":[{"name":"Division of Oncology, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8965-8129","authenticated-orcid":false,"given":"Matthew I.","family":"Milowsky","sequence":"additional","affiliation":[{"name":"Division of Oncology, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6753-3010","authenticated-orcid":false,"given":"Martin G.","family":"Pomper","sequence":"additional","affiliation":[{"name":"Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nicholas","family":"Wisniewski","sequence":"additional","affiliation":[{"name":"Department of Radiology, University of North Carolina, Chapel Hill, NC 27599, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ralph A.","family":"Bundschuh","sequence":"additional","affiliation":[{"name":"Department of Nuclear Medicine, Universit\u00e4tsklinikum Carl Gustav Carus at the TU Dresden, 01307 Dresden, Germany"},{"name":"German Cancer Consortium (DKTK), Partner Site Dresden, 01307 Dresden, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3372-6046","authenticated-orcid":false,"given":"Rudolf A.","family":"Werner","sequence":"additional","affiliation":[{"name":"Department of Nuclear Medicine, LMU University Hospital, LMU Munich, 80539 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8315-6603","authenticated-orcid":false,"given":"Michael A.","family":"Gorin","sequence":"additional","affiliation":[{"name":"Milton and Carroll Petrie Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Steven P.","family":"Rowe","sequence":"additional","affiliation":[{"name":"Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.eururo.2024.11.013","article-title":"Recent patterns and trends in global prostate cancer incidence and mortality: An update","volume":"87","author":"Schafer","year":"2025","journal-title":"Eur. 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