PI-RADS: Past, present, and future.

Prostate cancer (PCa) is extremely prevalent and is the most common noncutaneous malignancy and second-most common cause of cancer death in men. In the last decade, there has been dramatic growth in the use of multiparametric magnetic resonance imaging (mpMRI) for diagnosis and characterization of PCa. With the recent and marked surge in popularity in prostate imaging and, specifically, mpMRI, there has been an increased focus on structured reporting as a means by which to provide more actionable information to the referring clinician as well as to improve diagnostic performance with this technique. This work focuses on the evolution of the major structured reporting system in prostate mpMRI, Prostate Imaging Reporting And Data System (PI-RADS), from its initial proposal and establishment in 2012 as PI-RADS v. 1 to its most current iteration, PI-RADS v. 2.1. This will highlight the key elements that have changed between the versions as well as provide context and rationale for these changes. In addition, this work explores what future iterations of PI-RADS could look like based on current limitations of the system as well as explore areas for future growth of prostate mpMRI, including use of the system in active surveillance populations and in the posttreatment setting. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;52:33-53.