The study shows an increase in the NPV for exclusion of significant prostate cancer when PSA-Density is included as a parameter into the PIRADS-algorithm. 

Distler FA, Radtke JP, Bonekamp D, Kesch C, Schlemmer HP, Wieczorek K, Kirchner M, Pahernik S, Hohenfellner M, Hadaschik BA. The value of PSA density in combination with PI-RADS for the accuracy of prostate cancer prediction. J Urol. 2017 Mar 31. [Epub ahead of print]