Source of Funding: None MP05-03 ROBOTIC ASSISTED MRI-US FUSION GUIDED TARGET SATURATION BIOPSY OF THE PROSTATE; DIAGNOSTIC ACCURACY AND CLINICAL IMPLICATIONS Christian Wetterauer*, Pawel Trotsenko, Marc Matthias, Philipp Brantner, Lukas Bubendorf, Tatjana Vlajnic, David Winkel, Basel, Switzerland; Maciej Kwiatkowski, Aarau, Switzerland; Helge Seifert, Basel, Switzerland INTRODUCTION AND OBJECTIVE: MRI-targeted prostate bi- opsy improves the detection of clinically significant prostate cancer (PCa) and reduces overdetection of clinically insignificant cancer. However, up to 70% of PCa lesions display intralesional tumor het- erogeneity and current sampling strategies do not yet adequately ac- count for this finding. METHODS: This prospective study included 88 patients who underwent transperineal robotic assisted biopsy of the prostate at our institution from January 2020eJanuary 2021. We identified a total of 47 PCa-positive Pi-RADS lesions in 38 patients that were sampled by targeted saturation biopsies. We compared the diagnostic accuracy of a target-saturation biopsy strategy to the accuracy of single, two or three targeted biopsies, respectively and analyzed the potential clinical implications. RESULTS: Intralesional detection of clinically significant cancer (ISUP2) was 78.9% (30/38) for target-saturation biopsy and 28.9% (11/38), 39.5% (15/38) and 50% (19/38) for one, two and three targeted cores, respectively. Target-saturation biopsies led to a significantly more accurate characterization of PCa in terms of Gleason score and significantly reduced rates of cancer missed (p<0.05). Compared to one, two and three targeted biopsies, target- saturation biopsies led to intensified staging procedures in 11 (28.9%), 9 (23.7%) and 7 (18.4%) and ultimately to change in therapy in 19 (50%), 15 (39.5%) and 11 (28.9%) patients, respectively. CONCLUSIONS: This work presents the concept of robotic assisted target saturation biopsy and demonstrates the potential of this technique to improve diagnostic accuracy and its impact on individual treatment decisions. Source of Funding: Uromed: Research Grant MP05-04 CLINICALLY SIGNIFICANT PROSTATE CANCER DETECTION RATES ON MRI GUIDED FUSION NEEDLE BIOPSY - EXPERIENCE FROM THE PENNSYLVANIA UROLOGIC REGIONAL COLLABORATIVE Ako Adams Ako*, Serge Ginzburg, Philadelphia, PA; Eric Singer, New Brunswick, NJ; Bruce Jacobs, Pittsburgh, PA; Claudette Fonshell, Adam Reese, Edouard Trabulsi, Philadelphia, PA; Jeffery Tomaszewski, Camden, NJ; John Danella, Danville, PA; Laurence Belkoff, Bala Cynwd, PA; Thomas Guzzo, Robert Uzzo, Philadelphia, PA; Jay Raman, Hershey, PA INTRODUCTION AND OBJECTIVE: Magnetic resonance im- aging (MRI) fusion needle biopsy has been shown to outperform sys- tematic biopsy in detecting clinically significant prostate cancer. This study sought to: 1) Examine the variability of clinically significant prostate cancer detection rates in a large, regional quality improvement collaborative. 2) Examine the association between patient characteris- tics and clinically significant prostate cancer detection. METHODS: The Pennsylvania Urologic Regional Collaborative (PURC) is a physician-led data-sharing and quality improvement collaborative comprised of urology practices across Pennsylvania and New Jersey. We analyzed 857 first-time MRI fusion biopsy procedures performed at 5 PURC practices with a minimum of 30 procedures between January 2015 and June 2019. Chi-square tests and hierarchical logistic regression analyzed the variability in cancer detection rates by practice and the association between patient characteristics and Gleason 4þ3 tumor detection. RESULTS: Median prostate specific antigen (PSA) was 6.8 ng/ ml, 14.4% of men were 59 years old. Detection rates for Gleason 4þ3 tumors by practice ranged from 14.3% to 28.3% (p[0.02). Age, digital rectal examination, PSA, gland volume and Prostate Imaging-Reporting and Data System version2 (PI-RADSv2) score were significantly associated with Gleason 4þ3 tumors. Adjusting for patient characteristics demonstrated that there was no significant variation in Gleason 4þ3 tumor detection by practice (Intercept variance [ 0.04; p[0.26). PIRADSv2 4 was associated with increased likelihood of detecting a Gleason 4þ3 tumor (OR 2.67; 95% CI 1.76e4.07; p<0.0001). CONCLUSIONS: Variability in clinically significant prostate cancer detection between individual practice sites was predominantly due to variability in patient characteristics. Results highlight the impor- tance of pre-biopsy MRI in the diagnosis of clinically significant prostate cancer. Vol. 206, No. 3S, Supplement, Friday, September 10, 2021 THE JOURNAL OF UROLOGY Ò e77 Copyright © 2021 American Urological Association Education and Research, Inc. Unauthorized reproduction of this article is prohibited.