In-Bore MRI-guided Prostate Biopsies: Retrospective Observational Study of Complementary Nontargeted Sampling of Normal-appearing Areas at Multiparametric MRI.

Purpose: To investigate the pathologic outcomes of additional random biopsies from areas with no visible MR targets in the setting of targeted in-bore MRI-guided biopsy and to assess the negative predictive value (NPV) of areas with no visible MR targets stratified according to patients' different biopsy statuses. Materials and
Methods: A retrospective analysis of patients who underwent in-bore MRI-guided biopsy with additional random biopsies in areas with no visible MR targets (Prostate Imaging-Reporting and Data System, version 2 category 1 or 2) was conducted in this study. Diagnostic scans and in-bore MRI-guided biopsy were performed with a 3-T MRI scanner. Areas with no visible MR targets were biopsied in a random fashion whenever a zone or side did not have a visible focal target. Clinically significant cancers (CSCs) were defined as a Gleason score of 7 or greater. NPVs were stratified based on patient's prior biopsy status. Descriptive analysis was performed.
Results: A total of 59 consecutive patients were included, with a median age of 65 years (interquartile range [IQR], 59-71 years). The median prostate-specific antigen level was 7 ng/mL (IQR, 4.9-10.8 ng/mL). Of the 59 patients, 16 (27.1%) were biopsy naive, 24 (40.7%) had prior negative transrectal US-guided biopsy findings, and 19 (32.2%) had prior positive transrectal US-guided biopsy findings. Forty-two (71.2%) biopsies revealed prostate cancer. A total of 112 areas with no visible MR targets were biopsied, of which 20 (17.9%) were cancers and 11 (9.8%) were CSCs. The NPV of areas with no visible MR targets was approximately 78% for all cancers and was 88.1% for CSCs. NPVs in biopsy-naive patients, patients with prior negative transrectal US-guided biopsy findings, and patients with prior positive transrectal US-guided biopsy findings were 62.5%, 83.3%, and 84.2%, respectively, for all cancers and 75.0%, 91.7%, and 94.7%, respectively, for CSCs.
Conclusion: Areas with no visible MR targets in patients with MR-suspicious foci may still harbor CSCs that may significantly affect management plans. Additional biopsies from areas with no visible MR targets are warranted in this population.Keywords: Biopsy/Needle Aspiration, Interventional-Body, MR-Imaging, Prostate, Urinary© RSNA, 2019. 2019 by the Radiological Society of North America, Inc.