@article {Werner1317, author = {Rudolf Werner and Bilel Habacha and Lena Bundschuh and Takahiro Higuchi and Philipp Hartrampf and Liam Widjaja and Thorsten Derlin and Andreas Buck and Markus Essler and Kenneth Pienta and Mario Eisenberger and Mark Markowski and Martin Lodge and Martin Pomper and Michael Gorin and Ralph Bundschuh and Steven Rowe}, title = {Test-Retest Reproducibility of Conventional Quantitative Parameters on PSMA-targeted 18F-DCFPyL PET/CT in Patients with Metastatic Prostate Cancer}, volume = {62}, number = {supplement 1}, pages = {1317--1317}, year = {2021}, publisher = {Society of Nuclear Medicine}, abstract = {1317Objectives: Prostate-specific membrane antigen (PSMA)-targeted 18F-DCFPyL has proven to detect metastatic prostate cancer (PC) with high accuracy. In this study, we evaluated 18F-DCFPyL test-retest reproducibility of conventional quantitative parameters in widespread disease. Methods: In a prospective clinical trial (NCT03793543), 23 patients with histologically proven PC underwent two 18F-DCFPyL PET scans within 7 days (mean 3.7, range 1 to 7d). Lesions in bone, lymph nodes and other organs were manually segmented on both scans and quantitative parameters were assessed (mean [SUVmean] and maximum [SUVmax] standardized uptake values, PSMA-tumor volume [PSMA-TV] and total lesion PSMA [TL-PSMA, SUV x TV]). Repeatability of quantification was determined using correlations and within-subject coefficient of variation (wCOV, in \%; \<10\% indicating excellent, 10-20\% good, 20-30\% acceptable and \>30\% unacceptable reproducibility). Results: In total, 229 lesions (176 bone, 38 lymph nodes, 15 others) were delineated in both scans. For all investigated parameters, a high inter-scan correlation was found (R2>=0.98). Analyzing all lesions, the wCOVs for SUVmax and SUVmean were 12.1\% and 7.3\%, respectively, indicating good to excellent reproducibility for PSMA expression derived by SUV. The wCOV of LN, however, were significantly lower relative to those derived from osseous lesions (SUVmean: LN, 3.8\% vs. skeleton, 7.8\%, p\<0.0001; SUVmax: LN, 8.8\% vs. skeleton, 12.0\%, p\<0.03), supporting the notion that higher reproducibility for SUVs can be assessed in LN. Relative to SUV, TV-based features of all lesions demonstrated acceptable reproducibility (PSMA-TV, 23.5\%; TL-PSMA, 24.0\%). No significant difference could be assessed when comparing the wCOV of volumetric parameters in LN and osseus lesions (PSMA-TV: LN, 24.1\% vs. skeleton, 22.8\%, p=0.63; TL-PSMA: LN, 23.5\% vs. skeleton, 23.3\%, p=0.90). Conclusions: Relative to volumetric parameters, SUVs demonstrated a better reproducibility on 18F-DCFPyL PET, in particular for lymph node disease. Thus, SUV may be better suited as a reliable response assessment tool, for both existing studies and future trials.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/62/supplement_1/1317}, eprint = {https://jnm.snmjournals.org/content}, journal = {Journal of Nuclear Medicine} }