Minimum Magnetic Resonance Imaging-Ultrasound Fusion Targeted Biopsy Cores Needed for Prostate Cancer Detection: Multivariable Retrospective, Lesion Based Analyses of Patients Treated with Radical Prostatectomy.

PURPOSE: We analyzed the number of multiparametric magnetic resonance imaging targeted biopsy cores per lesion needed to detect prostate cancer in patients treated with radical prostatectomy. MATERIALS AND METHODS: Analyses focused on targeted biopsy of magnetic resonance imaging lesions suspicious for prostate cancer with a PI-RADS® (Prostate Imaging Reporting and Data System) score of 3 or greater and consecutive radical prostatectomy. Descriptive statistics included the frequency/proportion and IQR. Multivariable logistic regression analyses on the per lesion level were used to predict the number of targeted biopsies with prostate cancer. RESULTS: In the total cohort of 771 radical prostatectomy cases 437 (57%) and 334 (43%) were systematic transrectal ultrasound guided biopsy naïve or had 1 or more prior negative systematic transrectal ultrasound guided biopsies, respectively. A maximum PI-RADS score of 3, 4 and 5 was present in 67 (8.7%), 567 (74%) and 137 patients (18%), respectively. A total of 1,459 multiparametric magnetic resonance imaging lesions suspicious for prostate cancer were identified for analysis. Prostate cancer was detected based on an initial, second, third, or fourth or greater targeted biopsy in 79%, 92%, 98% and 100% of cases, respectively. The rate of prostate cancer detection on the first targeted biopsy core increased with higher PI-RADS scores of 3, 4 and 5 (67%, 79% and 87%, respectively). The number of prior negative systematic transrectal ultrasound guided biopsies and pathological tumor stage emerged as independent predictors on multivariate analysis, addressing the need for 2 or more targeted biopsy cores to detect clinically significant prostate cancer. CONCLUSIONS: Radical prostatectomy based analyses demonstrated that most cancers could be detected by 2 targeted biopsies only while in a minority of cases 3 or more targeted biopsies were necessary. Such findings might indicate that the targeted biopsy procedure and the related technology have improved, especially in patients with intermediate/high risk prostate cancer.