Histopathologic Yields and Concordance of In-Bore MRI-targeted Biopsy for Prostate Cancer Diagnosis.

Background MRI-targeted biopsies are recommended for prostate cancer diagnosis. In-bore MRI-targeted biopsy enables high-precision needle placement; however, the factors affecting prostate cancer detection rates and the potential for grade and patient risk migration require further investigation. Purpose To evaluate factors affecting the detection rate of prostate cancer in patients who underwent in-bore MRI-targeted biopsy and their influence on histologic concordance between biopsy (bGG) and surgical grade group (sGG). Materials and Methods This retrospective study evaluated in-bore MRI-targeted biopsies performed between March 2015 and January 2023. The agreement between bGG and sGG was assessed using Cohen weighted κ. The detection rate of prostate cancer and the concordance rates between bGG and sGG in patients undergoing prostatectomy were compared between biopsy systems (manual and robotic) and by patient biopsy status, lesion size (≤10 mm vs >10 mm), and Prostate Imaging Reporting and Data System (PI-RADS) category. Results In total, 780 lesions (patient median age, 65 years [IQR, 59-70 years]) were included. Among patients with previous negative biopsy and biopsy-naive patients, the detection rates of grade group (GG) 2 or higher cancer were higher in patients with PI-RADS category 4 or higher lesions (42.5% and 46.5%) and lesions larger than 10 mm (45.1% and 43.4%) ( < .05). Surgical upgrading was higher in lesions with bGG 1 than in those with bGG 2-4 cancers (66.1% vs 16.0% [ < .001]). In the 216 patients undergoing radical prostatectomy, bGG and sGG showed moderate to substantial agreement (weighted κ correlation coefficient, 0.61 [95% CI: 0.51, 0.71]). A downgrade of two or more grades between bGG and sGG was rare (5.7%). Histopathologic concordance did not depend on the PI-RADS category, target lesion size, biopsy system, or patient biopsy status ( = .90). Conclusion The in-bore MRI-targeted biopsy detection rates for GG 2 or higher prostate cancer depend on the target lesion size and PI-RADS category, and there is a substantial risk of histologic upgrades in men with GG 1 lesions at MRI-targeted biopsy. © RSNA, 2025 See also the editorial by Milot in this issue.