Perspective: a critical assessment of PI-RADS 2.1.

PI-RADS v2.1 addresses some of the shortcomings of its widely embraced precursor version 2, largely to simplify interpretation and improve interobserver agreement without changing the fundamental acquisition and scoring guidelines. Biparametric MRI is acknowledged in the newest version, but multiparametric MRI including dynamic contrast-enhanced imaging is still recommended for most scenarios. Management recommendations and guidance on evaluation of follow-up MRI's are still not included in the system.