Comparison of 18 F-PSMA-1007 PET/CT With 68 Ga-PSMA-11 PET/CT for Initial Staging in Intermediate- and High-Risk Prostate Cancer.

Purpose: This study aimed to compare 18 F-PSMA-1007 PET/CT with 68 Ga-PSMA-11 PET/CT for initial staging in intermediate- and high-risk prostate cancer (PCa) patients.

Methods: Forty treatment-naive, biopsy-proven, intermediate- or high-risk PCa patients were prospectively recruited. Each patient underwent PET/CT with 68 Ga-PSMA-11 and 18 F-PSMA-1007 (within 2 weeks). Assessment of both set of images included delineating number and characteristics of lesions, measurement of tracer uptake (SUV max ), miPSMA scoring, and PET-based stage categorization.

Results: Intraprostatic lesions were detected in all patients by both tracers with concordant PET-based T stage. Median SUV max of the dominant PSMA-positive prostatic lesions was not significantly different with 18 F-PSMA-1007 and 68 Ga-PSMA-11 (19.9 vs 19.4, P = 0.127, n = 40). Prostatic miPSMA scores were similar in 31/40 (77.5%) patients with both tracers (weighted κ = 0.71). In 23/40 (57.5%) patients, regional lymph nodes (n = 171) were detected by both tracers. Few additional PET-positive regional lymph nodes (n = 3) were exclusively detected by 18 F-PSMA in 2 patients without altering PET-based N stage. Extraregional lymph nodes (n = 123 in 17/40 patients) and visceral metastatic lesions (n = 18 in 3/40 patients) were detected concordantly by both tracers. PET-positive marrow based and skeletal metastases (n = 71) were detected in 14/40 (35%) patients by both tracers. Few additional marrow and skeletal lesions (n = 7) were exclusively detected on 18 F-PSMA-1007 in 5/14 patients, potentially upstaging PET-based M stage in 2/5 patients. Both radiotracers showed excellent interreader agreement for region-wise detection of lesions.

Conclusions: Our results suggest that 18 F-PSMA-1007 PET/CT is comparable to 68 Ga-PSMA-11 PET/CT in detecting primary and metastatic lesions of PCa.