The diagnostic performance and reader agreement of the Prostate Imaging for Recurrence Reporting system in the evaluation of local recurrence in patients with biochemically recurrent prostate cancer

Background The multiparametric magnetic resonance imaging (mpMRI)-based Prostate Imaging for Recurrence Reporting (PI-RR) system has been proposed to evaluate local recurrence in patients with prostate cancer (PCa) who have been treated with radiation therapy (RT) or radical prostatectomy (RP). Purpose To evaluate the diagnostic performance and interreader agreement of the PI-RR system in the diagnosis of locally recurrent PCa remains. Material and Methods A total of 110 patients who have biochemically recurrent PCa after RT (n = 35) or RP (n = 75) were included in this retrospective study. All patients underwent mpMRI, PSMA-PET/CT, and biopsy. Four radiologists with varying levels of expertise independently assessed the local recurrence of PCa using PI-RR. The reference standard was the biopsy pathology. The receiver operating characteristic (ROC) curve was used to evaluate the performance of PI-RR and PSMA-PET/CT, and areas under the ROC curve (AUC) were calculated. Interreader agreement across four readers was evaluated using the intraclass correlation coefficient (ICC). Results Among 110 patients with biochemically recurrent PCa, 28 had local recurrence and 82 had no local recurrence. Using a cutoff of 4, the AUCs of PI-RR in the diagnosis of local recurrence were in the range of 0.61–0.84 in patients treated with RT and 0.71–0.89 in patients treated with RP. The ICC was 0.86 (95% confidence interval = 0.81–0.91). Conclusion PI-RR using a cutoff of 4 has a favorable diagnostic performance and interreader agreement, which might be alternatively used for detecting local recurrence in patients with biochemically recurrent PCa treated with RT or RP.