Introduction: Micro-ultrasound (mUS) is a recently developed transrectal ultrasonography device with with high resolution (70um) for prostate cancer diagnosis. It has been implemented in the diagnostic process for screening and lesion targeting during prostate biopsies. This study reports on our clinical experience after introducing mUS into our prostate biopsy clinic. Methods: Data on 1002 consecutive patients imaged with the ExactVu mUS system between October 2017 and March 2022 were prospectively collected. All patients were scheduled for prostate biopsy due to clinical suspicion of PCa. The PRI-MUS protocol was used to locate targets on mUS. Lesions with a PRI-MUS score =3 were targeted. Patients were also subjected to systematic prostatic biopsies. The presence of overall PCa and of clinically significant PCa (defined as a Gleason score =7; csPCa) was determined and the diagnostic performance of mUS was assessed. Results: Mean age was 65.7(SD 8.0) yrs, median total PSA was 9.0(SD) ng/mL and median prostate volume was 50.0(IQR 35.0-70.0)mL. Overall, 389/1002 (38.9%) patients were in the repeat biopsy setting, with 149(14.9%) patients on active surveillance. MUS detected prostate lesions with a PRI-MUS score of 3, 4 and 5 in respectively 98(9.8%), 457 (45.7%) and 211(21.1%) patients, while in 236(23.6%) individuals mUS did not identify any target. Overall PCa and csPca detection rates were 51.7% and 36.5%(366). Micro-US provided high sensitivity, with 89.3% (327/366) of csPCa patients having at least one PRI-mMUS score =3 lesion. Similarly, NPV was 82.8% with 188/227 patients with no micro-US targets receiving a benign or insignificant PCa diagnosis (after systematic and MRI-target biopsy). Conversely, PPV and specificity were lower (42.2% and 18.6%), likely due to over-targeting. csPCa rate according to PRI-MUS score was in 26.5% for PRI- MUS 3, 35.2% (151/457) for PRI-MUS 4 and 58.5% (138/236) for PRI-MUS 5. The ratio between csPCa and overall PCa diagnosed increased with increasing PRIMUS score (60.5%, 65.7% and 90.8% for PRIMUS 3, 4 and 5 lesions). Conclusions: Our results confirm mUS as a fast and efficient modality with high accuracy for PCa diagnosis. It has a high sensitivity and negative predictive value for csPCa as well as allowing real-time lesion identification and targeting during prostate biopsy. SOURCE OF Funding: None.
