Microultrasonography-Guided vs MRI-Guided Biopsy for Prostate Cancer Diagnosis

Importance: High-resolution microultrasonography-guided biopsy is an alternative to MRI fusion-guided biopsy for prostate cancer diagnosis. Objective: To compare microultrasonography-guided and MRI fusion-guided biopsy. Design, Setting, and Participants: A multicenter, international, open-label, randomized, noninferiority trial of biopsy-naive men from 20 centers (8 countries) with clinical suspicion of prostate cancer (elevated prostate-specific antigen [PSA] and/or abnormal digital rectal examination findings) from December 2021 to September 2024. Interventions: Participants were assigned to receive either microultrasonography-guided biopsy (n = 121), microultrasonography/MRI fusion-guided biopsy (microultrasonography/MRI; n = 226, in which microultrasonography biopsies were performed prior to unblinding the MRI), or MRI/conventional US fusion-guided biopsy (MRI/conventional ultrasonography; n = 331). All participants received synchronous systematic biopsy. Main Outcomes and Measures: The primary outcome was the difference in detection of Gleason Grade Group 2 or higher cancers using microultrasonography plus systematic biopsy vs MRI/conventional ultrasonography plus systematic biopsy. The secondary outcome was the difference in detection of Gleason Grade Group 2 or higher cancers found using microultrasonography/MRI plus systematic biopsy vs MRI/conventional ultrasonography plus systematic biopsy. The noninferiority margin was set at 10%. Results: A total of 802 men underwent randomization and 678 underwent biopsy. Median (IQR) age was 65 (59-70) years and prostate-specific antigen level was 6.9 (5.2-9.8) ng/mL; 83% self-identified as White. Gleason Grade Group 2 or higher cancer was detected in 57 participants (47.1%) in the microultrasonography group, in 141 (42.6%) in the MRI/conventional ultrasonography group, and in 106 (46.9%) in the microultrasonography/MRI group. Microultrasonography-guided biopsy was noninferior to MRI fusion-guided biopsy (difference, 3.52% [95% CI, -3.95% to 10.92%]; noninferiority P < .001). Combined biopsy with microultrasonography/MRI was also noninferior to MRI/conventional ultrasonography software-assisted MRI fusion biopsy using conventional ultrasonography devices (difference, 4.29% [95% CI, -4.06% to 12.63%]; noninferiority P < .001). The rate of Gleason Grade Group 2 or higher cancer diagnosed by targeted biopsy only was 38.0% in the microultrasonography group, 34.1% in the MRI/conventional ultrasonography group, and 40.3% in the microultrasonography/MRI group; these differences were not significant. Conclusions and Relevance: The use of microultrasonography-guided biopsy was noninferior to MRI/conventional ultrasonography fusion-guided biopsy for the detection of Gleason Grade Group 2 or higher prostate cancer in biopsy-naive men. Microultrasonography may provide an alternative to MRI for image-guided prostate biopsy. Trial Registration: ClinicalTrials.gov Identifier: NCT05220501.