Introduction:

Multiparametric Magnetic Resonance Imaging (mpMRI) has been rapidly incorporated into the prostate cancer (PCa) diagnosis pathway. The Prostate Imaging Reporting & Data System (PI-RADS) scoring guidelines were developed to address the substantial variation in interpretation and reporting of mpMRI results, and subsequent updates have sought to further improve inter-reader reliability. Nonetheless, the variability of PI-RADS scoring in real-world settings may represent a continuing challenge to the widespread standardization of prostate mpMRI and limit its overall clinical benefit. In this study, we aimed to evaluate the discrepancies in PI-RADS scoring between community practices and a tertiary academic care center.

Methods:

In this retrospective cohort study, 262 patients with mpMRI studies originally performed at an outside non-academic facility that were interpreted by a radiologist at our institution between January 2016 and July 2022 were identified. Results of targeted MRI fusion biopsy were identified for 193 patients and represented a total of 302 lesions. For each lesion, PI-RADS scoring from both community and academic interpreters were recorded in addition to presence of clinically significant PCa (csPCa; International Society of Urological Pathology grade group 2 or higher) on pathological analysis of targeted cores. We assessed inter-reader reliability via intraclass correlation (ICC) and the kappa statistic. We assessed the diagnostic accuracy of PI-RADS scoring for detecting csPCa for both cohorts via receiver operator characteristics (ROC) analysis and compared these findings using paired-sample area difference under curve analysis.

Results:

Inter-reader agreement and reliability of PI-RADS scoring per lesion was generally poor (absolute agreement ICC=0.393, 95%CI: 0.288-0.488; consistency ICC=0.407, 95%CI: 0.308-0.497; kappa=0.336, 95%CI:0.267-0.406). Reliability results from studies obtained after the publication of PI-RADSv2.1 were similar to those of the overall analysis. No agreement was observed in the subgroup of lesions scored as PIRADS 3 by community interpreters. No statistically significant difference in diagnostic accuracy was observed between cohorts (ROC area under curve [AUC]: 0.759 vs 0.785, respectively; p=0.337). PI-RADS 3 was determined to be the optimal cutoff for detecting clinically significant disease in both cohorts.

Conclusion:

The PI-RADS scoring system is widely employed for the detection and evaluation of PCa using mpMRI. Our results suggest that diagnostic accuracy of mpMRI for detecting csPCa is not significantly different between academic and community practices. However, significantly poor reliability of mpMRI was observed between cohorts, suggesting the risk of introducing practice variation for prostate cancer management in the community. Future PI-RADS guideline updates should seek to further improve interobserver reliability, and further investigation of the current performance and limitations of mpMRI in more diverse clinical settings is warranted.

Funding: N/A