We prospectively investigated the performance of the prostate-specific membrane antigen (PSMA) ligand 68Ga-PSMA-11 for detecting prostate adenocarcinoma in patients with elevated prostate-specific-antigen (PSA) after initial therapy. Methods: 68Ga-PSMA-11 hybrid positron emission tomography (PET) was performed in 2005 patients at the time of biochemical recurrent prostate cancer (BCR) following either radical prostatectomy (RP) (50.8 %), definitive radiation therapy (RT) (19.7 %), or RP with post-operative RT (PORT) (29.6 %). Presence of prostate cancer was assessed qualitatively (detection rate = positivity rate) and quantitatively on a per-patient and per-region basis creating a disease burden estimate from presence or absence of local (prostate/prostate bed), nodal (N1: pelvis) and distant metastatic (M1: distant soft tissue and bone) disease. The primary study endpoint was the positive predictive value (PPV) of 68Ga-PSMA-11 PET/CT confirmed by histopathology. Results: Following prostatectomy, the scan detection rate increased significantly with rising PSA levels (44.8 % at PSA < 0.25 to 96.2 % at PSA > 10 ng/mL; P < 0.001). The detection rate significantly increased with rising PSA levels in each individual region, overall disease burden, prior androgen deprivation, clinical T-stage, and Gleason grading from prostatectomy specimen (P < 0.001). Following RT, the detection rate for in-gland prostate recurrence was 64.0 % compared to 20.6 % prostate bed recurrences after RP and 13.3 % following PORT. PSMA-positive pelvic nodal disease was detected in 42.7 % following RP, in 40.8 % after PORT and 38.8 % after RT. In patients with histopathologic validation the PPV per-patient was 0.82 (146/179). The SUVmax of histologically proven true positive lesions was significantly higher than false positive lesions (median 11.0 (IQR 6.3 - 22.2) vs 5.1 (IQR 2.2 - 7.4) P < 0.001). Conclusion: We confirmed a high PPV of 68Ga-PSMA-11 PET in BCR and the PSA level as the main predictor of scan positivity.
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2021 Jul 29 [Epub ahead of print]
Monica Abghari-Gerst, Wesley Robert Armstrong, Kathleen Nguyen, Jeremie Calais, Johannes Czernin, David Lin, Namasvi Jariwala, Melissa Rodnick, Thomas A Hope, Jason Hearn, Jeffrey S Montgomery, Ajjai Alva, Zachery R Reichert, Daniel E Spratt, Timothy D Johnson, Peter J H Scott, Morand Piert
Radiology Department, University of Michigan, United States., Ahmanson Translational Imaging Division, Department of Molecular and Medical Pharmacology, UCLA., Department of Radiology and Biomedical Imaging, UCSF., Department of Radiation Oncology, University of Michigan., Urology Department, University of Michigan., Internal Medicine Department, University of Michigan., Department of Biostatistics, University of Michigan.