How Many Targeted Biopsy Cores are Needed for Clinically Significant Prostate Cancer Detection during Transperineal Magnetic Resonance Imaging Ultrasound Fusion Biopsy?

Purpose: In this study we determined the optimal number of transperineal magnetic resonance imaging ultrasound fusion targeted biopsy cores per lesion needed for the detection of clinically significant prostate cancer. Materials and Methods: A total of 101 patients with at least 1 lesion with a PI-RADS (R) (Prostate Imaging Reporting and Data System) score of 3 or greater were recruited prospectively. At least 4 transperineal magnetic resonance imaging ultrasound fusion targeted biopsy cores per lesion were performed, followed by systematic biopsy. The Kappa test was used to evaluate the consistency of the clinically significant prostate cancer detection rate between different targeted biopsy cores and 4 or more cores, which was regarded as reference standard. Results: In the total cohort of 101 patients 49 (48.5%), 55 (54.5%) and 57 (56.4%) were diagnosed with clinically significant prostate cancer by systematic biopsy, targeted biopsy or targeted biopsy plus systematic biopsy, respectively. As for the total of 161 lesions, the clinically significant prostate cancer detection rate based on 1, 2, 3, or 4 or more targeted biopsy cores was made in 27.3%, 32.9%, 37.3% and 39.1%, respectively. Three cores showed great consistency with 4 or more cores in clinically significant prostate cancer detection rate (Kappa coefficient of 0.961, p <0.001) with a sensitivity of 95.2% (95% CI 85.8e98.8), and only missed 3 lesions harboring clinically significant prostate cancer. Similar results were obtained in cases with PI-RADS 3 or 4 or maximal diameter of less than 1.5 cm. Conclusions: Three targeted biopsies per lesion were suitable during transperineal magnetic resonance imaging ultrasound fusion biopsy, especially for lesions of PI-RADS 3 or 4, or small lesions (maximal diameter less than 1.5 cm), which may help to tailor targeted prostate biopsy procedures.