Evaluation of Diffusion-Weighted MR Imaging at Inclusion in an Active Surveillance Protocol for Low-Risk Prostate Cancer

Purpose: We aimed to determine whether diffusion-weighted magnetic resonance imaging, by means of the apparent diffusion coefficient (ADC), is able to guide magnetic resonance-guided biopsy in patients fit for active surveillance (AS) and identify patients harboring high-grade Gleason components not suitable for AS. Materials and Methods: Our study was approved by the institutional review board of all participating hospitals, and all patients signed informed consent at inclusion. Fifty-four consecutive patients with low-risk prostate cancer (PCa) underwent multiparametric magnetic resonance imaging (MP-MRI) at inclusion for AS. Cancer-suspicious regions (CSRs) upon 3-T MP-MRI were identified in all patients, and magnetic resonance-guided biopsy was performed in all CSRs to obtain histopathological verificat Results: Mean mADC in the CSRs with PCa was 1.04 x 10(-3) mm(2)/s (SD, 0.29), whereas the CSRs with no PCa displayed a mean mADC of 1.26 x 10(-3) mm(2)/s (SD, 0.25; P < 0.001). Cancer-suspicious regions with a high-grade Gleason component displayed a mean mADC of 0.84 x 10(-3) mm(2)/s (SD, 0.35) vs a mean mADC for the low-grade CSRs of 1.09 x 10(-3) mm(2)/s (SD, 0.25; P < 0.05). A diagnostic accuracy of mADC for predicting the presence of PCa in a CSR with an area under the receiver operating ch Conclusions: Median ADC is able to predict the presence and grade of PCa in CSRs identified by MP-MRI.