Diagnostic Performance of Perineal MRI-US Fusion Prostate Biopsy: A Single-Center Prospective Cohort Analysis.

Background: Transperineal magnetic resonance (MRI)/ultrasound (US) fusion-guided prostate biopsy has emerged as a promising alternative to the transrectal approach by improving lesion targeting and reducing infectious complications. However, real-world data addressing factors that influence the detection of clinically significant prostate cancer (csPCa), including imaging characteristics and procedural experience, remain limited. Objective: To evaluate the diagnostic performance, safety profile, and independent predictors of csPCa detection in patients who underwent transperineal MR/US fusion-guided prostate biopsy, with particular emphasis on PIRADS category, prostate-specific antigen (PSA) level, and procedural learning curve. Methods: In this study, patient data were prospectively recorded in a routinely maintained institutional database, while the present analysis was conducted retrospectively. A total of 136 patients with clinical suspicion of prostate cancer-defined as elevated prostate-specific antigen (PSA), abnormal digital rectal examination, or PIRADS ≥3 on multiparametric MRI-underwent transperineal MR/US fusion-guided biopsy between January 2023 and October 2024. Results: Prostate cancer was detected in 45.5% of patients, whereas csPCa was identified in 32.3%. The PIRADS category emerged as the strongest independent predictor of csPCa detection, with PIRADS-5 lesions showing a significantly greater likelihood of csPCa than PIRADS-3 lesions (OR 6.70, p = 0.006). The PSA level was also independently associated with csPCa detection (OR 1.06 per ng/mL increase, p = 0.033). Although csPCa detection rates increased across learning curve groups, procedural experience was not an independent predictor after adjustment. The procedure demonstrated a favorable safety profile, with a low rate of infectious and noninfectious complications despite minimal use of antibiotic prophylaxis. The multivariable model showed moderate explanatory power and acceptable overall classification accuracy. Conclusions: Transperineal MR/US fusion-guided prostate biopsy provides reliable detection of clinically significant prostate cancer with a low complication rate and consistent performance across different stages of institutional experience. The PIRADS category and PSA level remain key determinants of csPCa detection, supporting the integration of MRI-based risk stratification into contemporary prostate cancer diagnostic methods.