Prospective Evaluation of the Prostate Imaging Reporting and Data System Version 2 for Prostate Cancer Detection

Purpose: Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) was developed to standardize the interpretation and reporting of multiparametric prostate magnetic resonance imaging and provide guidelines for biopsy of multiparametric magnetic resonance imaging findings. We prospectively evaluated the cancer detection rate at each overall PI-RADSv2 score. Materials and Methods: This prospective study included 62 consecutive patients with 116 lesions who underwent multiparametric prostate magnetic resonance imaging at 3T with PI-RADSv2 evaluation and subsequent targeted magnetic resonance imaging/transrectal ultrasound fusion guided biopsy and concurrent 12-core systematic prostate biopsy between May and September 2015. Median patient age and prostate specific antigen values were 65.5 years( range 50.3 to 76.6) and 7.10 ng/ml( range 0.47 to 863.0), respectively. Mean lesion size was 12.7 mm overall. Lesion based cancer detection rates for all tumors and for Gleason 3+4 or greater tumors at each PI-RADSv2 score were calculated. Univariate analysis was performed to assess differences in the cancer detection rate among PI-RADSv2 scores. Results: A total of 116 lesions in 62 patients were evaluated prospectively ( 0 PI-RADS 1, 18 PI-RADS 2, 19 PI-RADS 3, 47 PI-RADS 4, 32 PI-RADS 5), and the patients underwent magnetic resonance/transrectal ultrasound fusion guided biopsy and systematic biopsy. Histopathology revealed 55 of 116( 47.4%) cancers( 17 Gleason 3+3, 16 Gleason 3+4, 6 Gleason 4+3, 12 Gleason 4+4, 3 Gleason 4+5 and 1 Gleason 5+4). Based on targeted biopsy on a per lesion basis, the overall cancer detection rates of PI-RADS 2, 3, 4 and 5 scores for all tumors was 22.2%, 15.8%, 29.8% and 78.1%, respectively. The cancer detection rate of PI-RADS 2, 3, 4 and 5 scores for Gleason 3_4 or greater tumors was 5.6%, 0%, 21.3% and 75%, respectively. Differences in the cancer detection rate between overall PI-RADS 4 and 5 scores were significant( p < 0.001 for Gleason greater than 3+3 and Gleason 3+4 or greater cancers). Conclusions: A PI-RADS score of 5 had the highest prospective cancer detection rate (78%). A PI-RADS score of 4 had only a 30% cancer detection rate, which is lower than expected. Surprisingly, no or few significant cancers were detected at a PI-RADS score of 3 (16%). These early prospective data suggest that current criteria result in a high false-positive rate that lowers the cancer detection rate. Therefore, stricter criteria may be needed in the future to decrease false-positives and increase the cancer detection rate for PI-RADS scores of 3, 4 and 5.