Detection rate of PSMA PET MRI (18 F-Flotufolastat) at the onset of biochemical recurrence following radical prostatectomy

Abstract Purpose The optimal timing to obtain the initial PET-PSMA imaging study when disease recurrence is suspected following RP is controversial. Methods 24 subjects with new onset of BCR following RP were enrolled. The initial PET MRI (study #1) was performed within 2 months of signing informed consent. Salvage treatment was offered only if site(s) of disease recurrence were identified by study #1. A second PSMA PET MRI (study #2) was performed 1 year following Study 1, or sooner if the 6-month PSA was > 0.5 ng/ml. PET/MR was performed in a dedicated scanner which allows simultaneous acquisition of PET and MR images following the IV administration of 8 m Ci of 18F-Flotufolastat (18F-rH PSMA, Blue Earth Diagnostics, UK). Results Disease recurrence was identified in 25% and 40% of subjects by study #1 and study #2, respectively. PSA doubling time with and without disease recurrence on study #2 was 12.8 months (IQR 4.0-17.2) and 20.8 months (20.8 months (IQR 9.1–51.7), respectively (p = 0.27). PSA prior to RP but not age, pathological grade, stage margin status or time to recurrence were significantly different between subjects with and without localization of disease recurrence. Conclusions The 25% disease detection and localizations justify performing PSMA PET MRI imaging at the onset of BCR. If the initial PSMA PET MRI does not identify site(s) of disease, our study supports repeating a PSMA PET study when the PSA is > 0.5 ng/ml or if the PSA doubling time is < 1 year. Clinical trial record The study is registered on ClinicalTrials.gov with study number NCT05678322.- Registration date 12/28/2022 URL of trial registry record: https://clinicaltrials.gov/study/NCT05678322