[18F]AlF-PSMA-11 PET in diagnosing prostate cancer: a head-to-head comparison with [68Ga]Ga-PSMA-11 PET and an exploration of dual-phase scanning.

Abstract

Purpose: To evaluate the physiological distribution and tumour detection ability of [¹⁸F]AlF-PSMA-11 positron emission tomography (PET) dual-phase scans in patients with prostate cancer (PCa).

Methods: As a retrospective study, clinical and PET data of PCa patients who underwent dual-phase [¹⁸F]AlF-PSMA-11 PET of routine scan (45-50 min) and delayed scan (120 min) from November 2020 to June 2021 were collected, and physiological and pathological regions of interest were quantified to determine the time-dependent maximum standardized uptake value (SUV_max) of [¹⁸F]AlF-PSMA-11. Part of the above subjects who underwent [⁶⁸Ga]Ga-PSMA-11 PET in the following 6 months were included in a head-to-head comparison. The difference with a p-value < 0.05 was defined as statistical significance. Diagnosis accuracy of primary and metastatic lesions was measured referring to the surgical findings, pathology, and follow-up imaging.

Results: [⁶⁸Ga]Ga-PSMA-11 and [¹⁸F]AlF-PSMA-11 were of the comparable uptake in glands in head, but the latter was of a significant lower distribution in liver and spleen. For the 25 patients initially diagnosed with prostate cancer and 3 patients with biochemical recurrence after radical surgery, the SUV_max of the primary lesions, lacrimal glands, parotid glands and submandibular glands was higher at 120 min compared to that at 45-50 min, but not a significant difference. SUV_max of the liver, spleen and bladder decreased significantly at 120 min, but the bladder SUV_max remained higher than that of primary lesions. SUV_max of the kidneys and centrum was the same in dual-phase scans. For the 31 primary lesions detected in [¹⁸F]AlF-PSMA-11 PET, both the SUV_max of the two phases kept the positive correlation with PSA, Gleason score and initial risk stratification. For the 39 distant metastatic lesions, 94.87% accuracy of routine scan and 100% accuracy of delayed scan were acquired, and 7.14% patients (2/28) benefited from the dual-phase [¹⁸F]AlF-PSMA-11 scans that revealed novel information on metastatic lesions compared to the routine scan.

Conclusion: [¹⁸F]AlF-PSMA-11 PET expanded the time window and further decreased metabolic background of [⁶⁸Ga]Ga-PSMA-11 PET. The dual-phase scan of [¹⁸F]AlF-PSMA-11 PET can benefit prostate cancer diagnosis via providing more PSMA-specific information.