This is a multicentre evaluation of prospective databases in men with phi result and MRI-guided targeted and systematic prostate biopsy performed. The additional value of phi to pre-biopsy MRI Prostate Imaging Reporting & Data System(PIRADS) version 2 score was evaluated with multivariate analyses and Cstatistics(AUC). The proportion of unnecessary biopsies that can be avoided are estimated for csPCa(ISUP group !2 PCa).RESULTS: Among the whole cohort of 2014 men without prior PCa diagnosis, 1183 men had pre-biopsy phi results available. The median(interquartile range) age, PSA, Prostate volume(PV), MRI lesion size, highest PIRADS score, targeted and systematic biopsy cores were 67(62-71), 8.0(5.8-11.0)ng/mL, 50.0(36.9-68.0)ml, 11(7-15)mm, 4(3-4), 3(3-4) cores and 12(12-18) cores respectively. Abnormal digital rectal exam(DRE) and Prior negative biopsy was seen in in 20.8% and 36.6% men respectively. PCa and csPCa was diagnosed in 51.3%(607/1183) and 35.3%(417/1181) men. csPCa was diagnosed in 4.7%, 15.5%, 40.1% and 74.2% of PIRADS 2, 3, 4 and 5 lesions respectively. In multivariate analyses, independent predictors for csPCa detection (odd ratio OR, 95%CI) included age(1.06,1.03-1.08), phi(1.04,1.03-1.04), PV(0.97, 0.96-0.98), and PIRADS score(reference PIRADS 2) [PIRADS 3 (3.3, PIRADS 4(8.2, PIRADS 5(21.6,]. AUC of predictors for csPCa were shown in the Table . Using a 5-factor risk score for csPCa in men with PIRADS score 2 or 3, 36.9%(90% sensitivity) and 19.4%(95% sensitivity) biopsies could be avoided. Decision curve analyses showed the 5-factor risk score achieving the best net clinical benefit.CONCLUSIONS: Adding phi test to men with MRI prostate performed improved csPCa prediction, and further reduced unnecessary biopsies using multivariable risk models especially in PIRADS 2 and 3 lesions. The observed benefits were superior to adding PSA density to MRI prostate.