Micro-ultrasound as an alternative to MRI in prostate cancer biopsy: Correlation with prostatectomy findings

BACKGROUND: Accurate detection of clinically significant prostate cancer (csPCa) is essential for treatment decisions. MRI-targeted biopsy improves accuracy but is limited by cost, availability, and inter-reader variability. Micro-ultrasound (microUS) is a high-resolution modality enabling real-time detection of suspicious lesions. OBJECTIVE: To compare the diagnostic accuracy of microUS-targeted biopsy plus systematic biopsy (microUS + SB) vs. MRI-targeted biopsy plus systematic biopsy (MRI + SB) using radical prostatectomy (RP) specimens as reference. METHODS: We retrospectively analyzed 142 patients undergoing perineal microUS-MRI fusion biopsy from January 2021 to July 2023 at Charité-Universitätsmedizin Berlin, followed by RP. Biopsy ISUP grades were compared with RP pathology per patient. CsCaP detection (ISUP ≥ 2) was evaluated with sensitivity, specificity, and AUC. Concordance was assessed using Wilcoxon signed-rank, Pearson Chi-Square, and McNemar-Bowker tests. RESULTS: MicroUS + SB was the only modality without significant deviation from RP ISUP grade (P = 0.065), whereas MRI + SB remained significantly different (P = 0.012). Sensitivity for csCaP was 73.3% for microUS + SB and 69.5% for MRI + SB, with similar positive predictive values (97.96% vs. 98.91%). AUCs were comparable (0.776 vs. 0.802). ISUP grading accuracy did not differ significantly (P = 0.127). No significant predictors of upgrading were identified, though a trend was seen for the number of positive microUS-targeted cores (P = 0.055). CONCLUSIONS: MicroUS + SB achieves comparable diagnostic accuracy to MRI + SB for csCaP. Its real-time imaging, cost-effectiveness, and accessibility make microUS a promising alternative to MRI. Prospective studies are warranted to confirm these findings.