Role of Magnetic Resonance Imaging Using Prostate Imaging-Reporting and Data System Version 2 to Predict Clinically Significant Cancer After Radical Prostatectomy in Very Low-Risk or Low-Risk Prostate Cancer

ABSTRACT

PURPOSE: To determine the negative predictive value (NPV) of multiparametric magnetic resonance imaging (mp-MRI) for clinically significant cancer (CSC) based on the Prostate Imaging-Reporting and Data System (PI-RADS) version 2 in very low-risk or low-risk prostate cancer patients. MATERIALS AND METHODS: We retrospectively analyzed 380 patients with low risk of prostate cancer who underwent mp-MRI before radical prostatectomy (RP) from 2011 to 2013. Of the 380 patients, 142 patients were in the very low risk group. CSC at RP was defined as follows: any T3−4, G3+4 with tumor volume>15%, G4+3 or higher. In the very low risk and low risk groups, we analyzed the rate of CSC according to PI-RADS score and calculated the NPV of mp-MRI for detection of CSC. RESULTS: In the low risk group, 20.8% (n=79) of patients had PI-RADS version 2 score 1–2 and 17.4% (n=66) of patients had PI-RADS version 2 score 3. In the very low risk group, 26.8% (n=38) of patients had PI-RADS version 2 score 1–2 and 17.6% (n=25) of patients had PI-RADS version 2 score 3 in the very low risk group. Rates of CSC were 33.7% (n=128) and 16.9% (n=24) in the low risk and very low risk groups, respectively. The NPV of MRI was 93.7% in the very low risk group and 78.6% in the low risk group. CONCLUSIONS: The NPV of PI-RADS for CSC is high in the very low risk group, but not in the low risk group. Further multicenter studies are needed to investigate the utility of PI-RADS version 2 for NPV.