Impact of delayed pelvic imaging on the staging of biochemical recurrence in prostate cancer patients using [18F]DCFPYL PET/CT: a retrospective evaluation.

Purpose: The aim of this study was to evaluate the added diagnostic value of additional second stage pelvic scanning as part of the [¹⁸F]DCFPYL PET/CT procedure in patients treated for prostate cancer (PCa) who have biochemical recurrence (BR).

Materials and methods: Consecutive patients with a diagnosis of PCa who underwent a dual-phase PSMA-PET scan between September 2022 and December 2023, were retrospectively included. We analyzed the number and maximum SUV (SUVmax) of lesions only in the pelvic region (prostate, locoregional lymph nodes and bone), based on PSMA-RADS version 2.0 and miTNM criteria. To assess the potential diagnostic benefit of additional delayed pelvic PET/CT imaging as part of the PSMA-PET procedure, the change in molecular TNM classification was evaluated after the procedure.

Results: Additional delayed pelvic PET/CT imaging as part of the PSMA-PET procedure resulted in a change in molecular TNM classification in 22 out of 136 patients (16.2%). The highest percentage change was obtained in the miN classification (14/22 patients), followed by the miT classification (7/22) and lastly miM (1/22). Moreover, we found that patients in whom delayed pelvic imaging resulted in a change in molecular TNM classification were significantly older and had a higher PSA level than those in whom delayed imaging did not provide additional information.

Conclusions: Pelvic delayed imaging in patients with biochemical recurrence of prostate cancer undergoing PET/CT with [¹⁸F]DCFPYL shows a non-negligible influence on patient staging, modifying the miTNM classification in 16.2% of cases, with pelvic lymphatic involvement benefiting the most from the dual study.