Comparison between 64Cu-PSMA-617 PET/CT and 18F-choline PET/CT imaging in early diagnosis of prostate cancer biochemical recurrence

In the clinical setting of biochemical recurrence after radical prostatectomy, current guidelines do not recommend the use of choline-based positron emission tomography (PET) with computed tomography (CT) with prostate-specific antigen (PSA) < 1 ng/mL. 64Cu-PSMA-617 PET/CT performed better than 18F-choline PET/CT in prostate cancer restaging, with a detection rate of 57.1% versus 14.3% in the 0.2-0.5 ng/mL PSA subgroup. Purpose: To evaluate the diagnostic performance of 64Cu-PSMA-617 positron emission tomography (PET) with computed tomography (CT) for restaging prostate cancer after biochemical recurrence (BCR) and to compare it with 18F-choline PET/CT in a per-patient analysis. Patients and Methods: An observational study was performed of 43 patients with BCR after laparoscopic radical prostatectomy who underwent 64Cu-PSMA-617 PET/CT and subsequently 18F-choline PET/CT for restaging. The detection rates (DR) of 64Cu-PSMA-617 PET/CT and of 18F-choline PET/CT were calculated by standardized maximum uptake value (SUVmax) at 4 hours and SUVmax at 1 hour as reference, respectively. Furthermore, univariate logistic regression analysis was carried out to identify independent predictive factors of positivity with 64Cu-PSMA-617 PET/CT. Results: An overall positivity with 64Cu-PSMA-617 PET/CT was found in 32 patients (74.4%) versus 19 (44.2%) with 18F-choline PET/CT. Specifically, after stratifying for prostate-specific antigen (PSA) values, we found a good performance of 64Cu-PSMA-617 PET/CT at low PSA levels compared to 18F-choline PET/CT, with a DR of 57.1% versus 14.3% for PSA 0.2-0.5 ng/mL (P =.031), and of 60% versus 30% with PSA 0.5-1 ng/mL. At univariate binary logistic regression analysis, PSA level was the only independent predictor of 64Cu-PSMA-617 PET/CT positivity. No significant difference in terms of DR for both 64Cu-PSMA-617 PET/CT and 18F-choline PET/CT was found according to different Gleason score subgroups. Conclusion: In our study cohort, a better performance was observed for 64Cu-PSMA-617 PET/CT compared to 18F-choline PET/CT in restaging after BCR, especially in patients with low PSA values.