Abstract
1323
Introduction: Prostate-specific membrane antigen (PSMA) PET/CT is increasingly used in the staging and management of prostate cancer. The most published tracer in PSMA PET/CT is 68Ga-PSMA-11 (PSMA-11). However, 18F-PSMA-1007 (PSMA-1007) has several potential advantages over PSMA-11, including non-urinary clearance, which may improve accuracy of prostate cancer detection in the prostate fossa. The aim of this study is to prospectively compare the diagnostic accuracy of PSMA-11 with PSMA-1007 in the detection of locally recurrent and metastatic prostate cancer in men with biochemical recurrence (BCR) following radical prostatectomy (RP).
Methods: Men with a rising PSA after RP were prospectively recruited to undergo both PSMA-11 and PSMA-1007 PET/CT. Images were reported by two experienced readers (a third in the case of discordance) blind to clinical and imaging information. Clinical, pathological, and follow-up data were recorded. PSMA-11 was used to guide treatment, and a composite reference standard formulated to evaluate diagnostic value.
Results: 14 men underwent both PSMA-11 and PSMA-1007 PET/CT within two weeks (mean PSA at imaging 0.21 ± 0.15 ng/mL). 8/14 men had negative results on both modalities. 2/14 men had lesions on PSMA-11 alone, 1/14 had a lesion on PSMA 1007 alone (false positive) and 3/14 men had lesions on both. 8 lesions were detected. PSMA-11 detected 7, whilst PSMA-1007 detected 5. Based on the reference standard, 7/8 were considered true positives; a bone lesion on PSMA-1007 alone was considered false positive. 3 lesions were identified in the prostate fossa on PSMA-11 compared with one on PSMA-1007. Kappa scores for inter-observer agreement were higher in PSMA-11 compared to PSMA-1007 group.
Conclusions: Detection rates in PSMA-1007 PET/CT were not superior to PSMA-11 in men with BCR post-RP. Despite low renal excretion, detection of local recurrences in the prostate fossa was not improved with PSMA-1007.