Diagnostic performance of 18F-PSMA-1007 PET/CT in biochemically relapsed patients with prostate cancer with PSA levels ≤ 2.0 ng/ml

The aim of the study was to prospectively evaluate diagnostic performance of 18F-PSMA-1007 PET/CT in patients with prostate cancer (PCa) after radical treatment and low but rising prostate-specific antigen (PSA) levels. We prospectively enrolled 40 consecutive patients after radical treatment (80%—radical prostatectomy, 20%—radiation beam therapy) of PCa and low (0.008 to ≤2.0 ng/ml), rising PSA. Skull to mid-thigh PET/CT imaging was performed 95 (±12) min after injection of 295.5 (±14.1) MBq 18F-PSMA-1007. Detection rate was correlated with PSA levels, Gleason score (GS) and T stage ≥ 3. PET/CT results were verified during 10.3 (±4.7) months follow-up to calculate sensitivity, specificity, negative predictive values (NPV) and positive predictive values (PPV). 18F-PSMA-1007 PET/CT was positive in 24/40 patients, which yielded overall detection rate of 60%. Detection rate was 39%, 55% and 100% for PSA < 0.5, 0.5 to <1.0 and 1.0 to ≤2.0 ng/ml, respectively. PET/CT showed metastases in locoregional lymph nodes in 55% of patients, bones in 36% of patients and local recurrence in 9% of patients. Detection rate was correlated with PSA—a 0.1 ng/ml rise in PSA level increased odds for positive PET/CT by ~30%. PET/CT positivity was independent of GS and T stage. Verification of 40 lesions yielded sensitivity, specificity, PPV and NPV of 100%, 94.4%, 66.7% and 100%, respectively. 18F-PSMA-1007 PET/CT shows relatively high detection rate in patients with PCa after radical treatment and low, rising PSA levels. Like other PSMA-targeting radiotracers, its detection rate is dependent on PSA levels. 18F-PSMA-1007 also presents excellent sensitivity, specificity and NPV.