Synthesis and clinical evaluation of cyclotron-produced [ 68 Ga]PSMA-11 and [ 18 F]PSMA-1007 for prostate cancer imaging.

Abstract

Objective: To compare the radiochemical synthesis, stability, and clinical performance of cyclotron-produced [ 18 F]PSMA-1007 and [⁶⁸Ga]PSMA-11 for prostate-specific membrane antigen (PSMA)-targeted PET/computed tomography (CT) imaging in prostate cancer.

Methods: Six production runs each of [¹⁸F]PSMA-1007 and [⁶⁸Ga]PSMA-11 were conducted using a cyclotron-based system. Radiochemical yield, radiochemical purity, and product stability were evaluated according to European Pharmacopeia standards. Thirty-five patients with prostate cancer underwent dual-tracer PET/CT imaging within 30 days. Images were assessed for lesion detectability, biodistribution, and pitfalls by three independent nuclear medicine physicians using semiquantitative metrics.

Results: [¹⁸F]PSMA-1007 demonstrated substantially higher end-of-synthesis activity (mean: 75.68 GBq) compared with [⁶⁸Ga]PSMA-11 (mean: 1.76 GBq), with both achieving high RCP (>98%) and comparable synthesis durations. Stability testing confirmed [¹⁸F]PSMA-1007 remained radiochemically stable for up to 9 h. Clinically, both tracers showed high concordance in PSMA-avid lesion detection. [¹⁸F]PSMA-1007 exhibited superior contrast in prostate and skeletal lesions because of minimal urinary excretion but also revealed higher rates of benign uptake in ganglia and nonspecific bone sites, leading to increased discordant findings (104 vs. 47 lesions).

Conclusion: [¹⁸F]PSMA-1007 provides significant advantages in production scalability and lesion detectability, particularly in skeletal and pelvic regions; however, its higher rate of benign uptake necessitates careful interpretation to avoid false positives. While both tracers are clinically effective, tracer selection should be guided by logistical feasibility, clinical context, and interpretive considerations.