Claudia Ortega1, Josh Schaefferkoetter1,2, Patrick Veit-Haibach1, Reut Anconina1, Alejandro Berlin3, Nathan Perlis4, Ur Metser5. 1. Joint Department of Medical Imaging, Princess Margaret Hospital, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, Toronto, Ontario, Canada. 2. Siemens Healthcare Limited, Oakville, Ontario, Canada. 3. Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada; and. 4. Urologic Oncology, University Health Network, Princess Margaret Cancer Centre Research Institute, University of Toronto, Toronto, Ontario, Canada. 5. Joint Department of Medical Imaging, Princess Margaret Hospital, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, Toronto, Ontario, Canada ur.metser@uhn.ca.
Abstract
Our purpose was to determine the effect of a smoothing filter and partial-volume correction (PVC) on measured prostate-specific membrane antigen (PSMA) activity in small metastatic lesions and to determine the impact of these changes on molecular imaging PSMA (miPSMA) scoring. Methods: Men who had biochemical recurrence of prostate cancer with negative findings on CT and bone scintigraphy were referred for 18F-DCFPyL (2-(3-(1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl) PET/CT. Examinations were performed on 1 of 2 different brands of PET/CT scanner. All suspected tumor sites were manually contoured on coregistered CT and PET images, and each was assigned an miPSMA score as per the PROMISE criteria. The PVC factors were calculated for every lesion using the anatomic CT and then applied to the unsmoothed PET images. The miPSMA scores, with and without the corrections, were compared, and a simplified rule-of-thumb (RoT) correction factor (CF) was derived for lesions at various sizes (<4 mm, 4-7 mm, 7-9 mm, and 9-12 mm). This CF was then applied to the original dataset and the miPSMA scores that were obtained using the RoT CF were compared with those obtained using the actual corrections. Results: There were 75 men (median age, 69 y; median serum PSA, 3.69 μg/L) with 232 metastatic nodes less than 12 mm in diameter (mean lesion volume, 313.5 ± 309.6 mm3). The mean SUVmax before and after correction was 11.0 ± 9.3 and 28.5 ± 22.8, respectively (P < 0.00001). The mean CF for lesions smaller than 4 mm (n = 22), 4-7 mm (n = 140), 7-9 mm (n = 50), and 9-12 mm (n = 20) was 4 (range, 2.5-6.4), 2.8 (range, 1.6-4.9), 2.3 (range, 1.6-3.3), and 1.8 (range, 1.4-2.4), respectively. Overall, the miPSMA scores were concordant between the corrected dataset and the RoT dataset for 205 of 232 lesions (88.4%). Conclusion: A smoothing filter and PVC had a significant effect on measured PSMA activity in small nodal metastases, impacting the miPSMA score.
Our purpose was to determine the effect of a smoothing filter and partial-volume correction (PVC) on measured prostate-specific membrane antigen (PSMA) activity in small metastatic lesions and to determine the impact of these changes on molecular imaging PSMA (miPSMA) scoring. Methods:Men who had biochemical recurrence of prostate cancer with negative findings on CT and bone scintigraphy were referred for 18F-DCFPyL (2-(3-(1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl) PET/CT. Examinations were performed on 1 of 2 different brands of PET/CT scanner. All suspected tumor sites were manually contoured on coregistered CT and PET images, and each was assigned an miPSMA score as per the PROMISE criteria. The PVC factors were calculated for every lesion using the anatomic CT and then applied to the unsmoothed PET images. The miPSMA scores, with and without the corrections, were compared, and a simplified rule-of-thumb (RoT) correction factor (CF) was derived for lesions at various sizes (<4 mm, 4-7 mm, 7-9 mm, and 9-12 mm). This CF was then applied to the original dataset and the miPSMA scores that were obtained using the RoT CF were compared with those obtained using the actual corrections. Results: There were 75 men (median age, 69 y; median serum PSA, 3.69 μg/L) with 232 metastatic nodes less than 12 mm in diameter (mean lesion volume, 313.5 ± 309.6 mm3). The mean SUVmax before and after correction was 11.0 ± 9.3 and 28.5 ± 22.8, respectively (P < 0.00001). The mean CF for lesions smaller than 4 mm (n = 22), 4-7 mm (n = 140), 7-9 mm (n = 50), and 9-12 mm (n = 20) was 4 (range, 2.5-6.4), 2.8 (range, 1.6-4.9), 2.3 (range, 1.6-3.3), and 1.8 (range, 1.4-2.4), respectively. Overall, the miPSMA scores were concordant between the corrected dataset and the RoT dataset for 205 of 232 lesions (88.4%). Conclusion: A smoothing filter and PVC had a significant effect on measured PSMA activity in small nodal metastases, impacting the miPSMA score.
Authors: Rudolf A Werner; Bilêl Habacha; Susanne Lütje; Lena Bundschuh; Takahiro Higuchi; Philipp Hartrampf; Sebastian E Serfling; Thorsten Derlin; Constantin Lapa; Andreas K Buck; Markus Essler; Kenneth J Pienta; Mario A Eisenberger; Mark C Markowski; Laura Shinehouse; Rehab AbdAllah; Ali Salavati; Martin A Lodge; Martin G Pomper; Michael A Gorin; Ralph A Bundschuh; Steven P Rowe Journal: Mol Imaging Date: 2022-02-23 Impact factor: 4.488