Comparison of micro-ultrasound and multiparametric magnetic resonance imaging in detecting clinically significant prostate cancer: a single-center experience

Objectives: Multiparametric magnetic resonance imaging (mpMRI) represents a cornerstone of prostate cancer (PCa) diagnosis; however, it is not without limitations, particularly in terms of specificity and real-world implementation. High-resolution 29-MHz micro-ultrasound (microUS) has recently emerged as a complementary imaging modality, with the potential to enhance lesion detection and refine mpMRI-based diagnostic pathways. This study aims to compare the diagnostic performance of microUS and mpMRI for the detection of clinically significant prostate cancer (csPCa), and to evaluate the clinical value of integrating microUS into mpMRI-based diagnostic pathways. Methods: This single-center retrospective study included 457 men undergoing prostate biopsy for suspected prostate cancer or during active surveillance between May 2023 and November 2025. All patients underwent microUS-guided biopsy using the ExactVu™ system, along with systematic biopsies and mpMRI-targeted biopsies performed when indicated. csPCa was defined as ISUP Grade Group ≥ 2. Diagnostic performance metrics were calculated for mpMRI and microUS. Receiver operating characteristic (ROC) analysis was performed using ordinal PI-RADS and PRIMUS scores. Decision curve analysis was used to assess the net clinical benefit of integrated diagnostic strategies. Multivariate logistic regression adjusted for age, initial PSA, and clinical stage was performed. Results: csPCa was detected in 44% of patients. mpMRI showed high sensitivity (92%) but low specificity (28%), whereas microUS showed a more balanced profile (sensitivity 70%, specificity 66%) and higher overall accuracy (68% vs. 57%). ROC analysis based on imaging scores showed comparable performance between mpMRI (AUC = 0.7) and microUS (AUC = 0.72; p = 0.41). Decision curve analysis demonstrated that diagnostic pathways integrating microUS with mpMRI provided greater net clinical benefit across clinically relevant threshold probabilities compared with strategies based on either modality alone. On multivariate analysis, both mpMRI and microUS positivity were independently associated with csPCa detection. Conclusions: MicroUS demonstrated diagnostic performance comparable to mpMRI and provided complementary information when integrated into mpMRI-based diagnostic pathways. These findings support the use of microUS as an adjunct to mpMRI to improve clinical decision-making within the PCa diagnostic workflow.