3:18 PM Abstract No. 110 Detection rate of clinically significant prostate cancer using in-bore 3T magnetic resonance–guided biopsy in 379 patients: an update based on PIRADS v2.1 assessment

We aimed to update the diagnostic yield of in-bore 3Tesla magnetic-resonance-guided biopsy (3T-MRGB) for prostate cancer (PCa) detection based on the assessment by recently described Prostate Imaging Reporting and Data System version 2.1(PIRADSv2.1). This IRB-approved, HIPAA-compliant, retrospective, single-center study examined individuals who underwent 3T multiparametric prostate MRI and subsequent trans-rectal in-bore 3T-MRGB between February 2012 and March 2019. The final study cohort included 379 men (median age, 68 years), divided into three subcohorts: biopsy-naïve men (N = 123), individuals with history of recent (< 1 year) negative trans-rectal ultrasound biopsy (TRUS-bx) (N = 106) and men with low-grade PCa under active surveillance (AS) (N = 150). Gleason score ≥ 3+4 was considered as clinically significant prostate cancer (csPCa). Overall, 475 targets were sampled in 379 individuals. The rate of urosepsis was 1% (4 patients). PCa detection rate at patient level was 69.1% (262/379), of whom 73.7% (193/262) had csPCa. At target level, PCa detection rate was 64.2% (305/475) of which 68.2% (208/305) were csPCa. The core positivity percentage was 46.2%. We found overall csPCa detection rate of 36.8%, 52.8% and 50.7% in prior negative TRUS-bx, biopsy-naïve, and AS subcohorts, respectively. The detection rate of PCa was comparable between transition zone (63.8%, 143/224) and peripheral zone (64.5%, 162/251) targets (P >0.5). Positive predictive values of PIRADSv2.1 categories 3, 4 and 5 for csPCa detection were 24.8%, 44.4% and 67.1%, respectively. Higher PIRADSv2.1 category was significantly associated with PCa (OR:3.97, 95% CI:2.98-5.28) and csPCa (OR:1.41, 95%CI:1.03-1.94) detection. PIRADSv2.1 allowed downgrading of 26/137 of MRGB-negative lesions with PIRADSv2 category 3 to PIRADSv2.1 category 2. In-bore 3T MRGB resulted in csPCa detection in half of the individuals under AS and in more than a third of patients with negative TRUS-bx. PIRADS v2.1 assessment is a strong tool to predict the detection of PCa and csPCa.