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.