The Relationship between PI-RADS Categories and Incidental Findings in Multiparametric Prostate MRI

Objective: To find the frequency and significance of extraprostatic incidental findings (ep-IFs) during multiparametric-magnetic prostate resonance imaging (mp-MRI), and compare them with prostate imaging reporting and data system (PI-RADS) outcomes. Study Design: Analytical study. Place & Duration of Study: Goztepe Education and Research Hospital, Istanbul, Turkey, from June 2019 to January 2020. Methodology: Images of 185 men, who underwent mp-MRI, were reviewed and ep-IFs were also classified as urologic or non-urologic and benign or malign. The PI-RADS score was also recorded in biopsy-naive subjects or in whom a sufficient time (which would not impair imaging) was elapsed after the biopsy. The cases were also divided into two groups, according to the PI-RADS score (Group 1: PI-RADS 1 or 2, Group 2: PI-RADS 3 or more) and the incidental findings (IFs) were compared between the groups. Results: Overall, 139 ep-IFs were detected in 88 (47.6%) patients. The remaining 97 (52.4%) cases were free of ep-IFs. The ep-IFs were benign in 85 (96.6%) and malignant in 3 (3.4%) cases. The frequency of total ep-IFs did not differ between groups 1 and 2 (47.8% vs. 47.6%, respectively, p>0.05). Conclusion: Extra prostatic incitental findings are frequently encountered during mp-MRI, benign ep-IFs are quite frequent; although rare malignant ep-IFs may be subject to being missed due to focused analysis and interpretation of prostate. PI-RADS scoring system does not contribute to the diagnosis of incidental mp-MRI.