Early Detection of Biochemical Recurrence in Prostate Cancer Patients with PSA Levels ≤0.5 ng/mL; Comparison Study between [ ¹⁸ F]PSMA-1007 and [ ⁶⁸ Ga]Ga-PSMA-11 PET/CT

PURPOSE: This study compared the correct detection rates (CDR) of [¹⁸F]PSMA-1007 and [⁶⁸Ga]Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in patients with prostate-specific antigen (PSA) ≤0.5 ng/mL after radical prostatectomy. MATERIALS AND METHODS: This retrospective study included 88 patients who underwent [¹⁸F]PSMA-1007 (n=41) or [⁶⁸Ga]Ga-PSMA-11 PET/CT (n=47) for PSA ≤0.5 ng/mL after radical prostatectomy. Patients were stratified into ultra-low biochemical recurrence (u-BCR, <0.2 ng/mL) and early BCR (e-BCR, 0.2-0.5 ng/mL) groups. CDRs, defined as the proportion of patients with true positive findings for each imaging modality, and positive predictive values (PPVs) were compared between radiotracers. RESULTS: 3.8%, p<0.001), while lymph node (LN) and distant metastases detection was comparable. In the u-BCR group, the recurrence sites identified by [¹⁸F]PSMA-1007 included local (n=3), LN (n=3), bone (n=2), and local plus LN (n=1), whereas [⁶⁸Ga]Ga-PSMA-11 identified local (n=1), LN (n=1), bone (n=1), and lung (n=1). In [¹⁸F]PSMA-1007, CDR was higher in high/very high-risk than in low/intermediate-risk patients in the u-BCR group (p=0.011). No such difference was observed with [⁶⁸Ga]Ga-PSMA-11. PPVs did not differ significantly between radiotracers (p=0.333). CONCLUSIONS: [¹⁸F]PSMA-1007 PET/CT showed higher CDR than [⁶⁸Ga]Ga-PSMA-11 PET/CT in patients at PSA ≤0.5 ng/mL after radical prostatectomy. Given the high detection performance, these findings support consideration of [¹⁸F]PSMA-1007 PET/CT for detection at PSA ≤0.5 ng/mL, particularly for prostate bed assessment in high/very high-risk patients.