In-bore MRI-guided biopsy: can it optimize the need for periodic biopsies in prostate cancer patients undergoing active surveillance? A pilot test-retest reliability study.

OBJECTIVE: To evaluate the test-retest reliability of repeated in-bore MRI-guided prostate biopsy (MRGB). METHODS: 19 lesions in 7 patients who had consecutive MRGBs were retrospectively analysed. Five patients had 2 consecutive MRGBs and two patients had 3 consecutive MRGBs. Both multiparametric MRI and MRGBs were performed using a 3T MRI scanner. Pathology results were categorized into benign, suspicious and malignant. Consistency between first and subsequent biopsy results were analysed as well as the negative predictive value (NPV) for prostate cancer. RESULTS: 15 lesions (≈79%) had matching second biopsy and 4 (21%) had non-matching second biopsy. Lesions with both Prostate Imaging - Reporting and Data System(PIRADS) categories 1 and 4 were all benign and had matching pathology results. Lesions with non-matching results had PIRADS categories 2, 3 and 5. NPV for prostate cancer in first biopsy was 87.5%. Overall agreement was 78.9% and overall disagreement was 21.1%.κ = 0.55 denoting moderate agreement (p = 0.002). 10/19 lesions had a third biopsy session. 9/10 (90%) had matching pathology results across the three biopsy sessions and all matching lesions were benign. CONCLUSION: In-bore MRI-guided prostate biopsy may have a better reliability for repeat biopsies compared to TRUS biopsy. Final conclusion awaits a prospective analysis on a larger cohort of patients. Advances in knowledge: This pilot study showed that repeated prostate in-bore MRI-guided prostate biopsy may have better reliability compared to TRUS biopsy with a suggested high NPV.