MP58-15: Assessing the role of high-resolution micro-ultrasound among patients with a negative multiparametric MRI and a persistent suspicion of prostate cancer.

Pier Paolo Avolio*, Milan, Italy, Vittorio Fasulo, Cesare Saitta, Pietro Diana, Alessandro Uleri, Andrea Gobbo, Paola Arena, Edoardo Beatrici, Giuseppe Chiarelli, Contieri Roberto, Nicola Frego, Davide Maffei, Alberto Saita, Paolo Casale, Giorgio Ferruccio Guazzoni, Massimo Lazzeri, Rodolfo Hurle, Giovanni Lughezzani, Nicolò Maria Buffi, Milano, Italy

Introduction: Multi-parametric MRI (mpMRI) has significantly changed the diagnostic pathway of patients with suspicion of prostate cancer (PCa). However, a significant proportion of patients without suspicious lesions at mpMRi may harbour PCa. To assess whether high resolution micro-ultrasound (microUS) could help in sub-stratifying the presence of PCa and clinically significant prostate cancer (csPCa) in patients with a negative mpMRI but persistent clinical suspicion of PCa.

Methods: We retrospectively reviewed the data of 66 patients who underwent biopsy having a negative mpMRI with persistent clinical/laboratory suspicion of PCa. All patients received microUS before prostate biopsy using the ExactVu system; the Prostate Risk Identification using microUS (PRI-MUS) protocol was used to identify targets. The urologists were blinded to MRI results until after the microUS targeting was completed. All patients also received systematic biopsies. The accuracy of microUS to determine the presence of PCa and csPCa (defined as at least one core with a Gleason score =7 PCa) in this setting was determined. The detection rates for csPCa were also stratified according to the presence of a cribriform pattern =35% in the histological examination after biopsy. Multivariable logistic regression models (MLRMs) were fitted to determine the predictors of PCa.

Results: Overall, 18 patients (27.3%) did not show any lesion at microUS (PRI-MUS 1-2) while in the remaining 48 (72.7%) patients at least 1 target lesion was identified (PRI-MUS =3). 21 (31.8%) harboured PCa and 12 (18.2%) csPCa. Among patients without lesions at microUS, only 1 (5.6%) patient was diagnosed with a Gleason grade group (GG) 1, thus yielding a NPV of 100%. Among patients with at least 1 PRI-MUS =3 lesion, 28 (58.3%) had a negative biopsy, while 20 (41.7%) and 12 (25%) were diagnosed with PCa and csPCa, respectively. Specifically, 1 patient had a PRI-MUS 3 lesion, 15 patients had a PRI-MUS 4 lesion, while 4 patients had a PRI-MUS 5 lesion. In this setting, microUS showed a high sensitivity (95.2%) and negative predictive value (94.4%), while its specificity and positive predictive value were 37.8% and 41.7%, respectively. Among patients with GG =2, 6 (50%) had a cribriform pattern =35% at histologic examination after biopsies. In MLRMs, lesion identified at microUS and family history were independent predictors of PCa. The accuracy of a model including PRI-MUS score, previous biopsies, PSA density, age and family history was 0.77 (95% CI: 0.66 - 0.88).

Conclusions: MicroUS could represent a helpful tool capable of discriminating patients harbouring csPCa among subjects without lesions at MRI but persistent suspicion of PCa. Further prospective studies on larger populations are needed to validate our results.

Source of Funding: None