I am Dr. Steven Pomerantz here with MRI online talking about the changes, revisions and clarifications for PI-RADS 2.1. In order to understand these changes you have to have a firm understanding of how we got here. So let's create a couple of definitions. First, multiparametric prostate MRI. In multiparametric assessment you're using more than two criteria to come up with a grading system, so that might include T2 criteria, diffusion weighted imaging criteria, dynamic contrast enhanced MRI criteria and maybe even spectroscopic criteria. On the other hand bi, meaning two, means we're using two important criteria to make the determination of our final PI-RADS designation. And those two criteria do not utilize an IV or contrast enhanced MRI. So they're simpler, they save time and they would include T2 criteria and diffusion weighted imaging criteria. And within that we have the ADC map which is formed from diffusion weighted imaging acquisition.
Now another important basic understanding of how you come up with a PI-RADS designation includes the fact that you take each one of these categories and you break them down one, two, three, four and assign them a designation based on certain criteria within the T2 relaxation event. Similarly, you're going to come up with criteria one, two, three, four for diffusion weighted imaging. These criteria are some of the things that have changed within these areas. For instance, T2 criteria in the prostate have been modified, so what we might've called a one or two or three or four may have changed. So that'll help clarify some of the discussions we're about to have.
Many of these changes in criteria revolve around the middle portion of the prostate, the inner portion of the prostate, known as the TZ or transitional zone and that's where we're going to concentrate a lot of our effort to understand the clarification, the modification and the frank changes that have been made in PI-RADS 2.1.
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Content reviewed: December 29, 2021