Dr. P here giving you some updates on PI-RADS 2.1. Want to start with something very simple. As I scroll a little bit here, I'll use my trusty pencil. Dialing in with the color yellow, I'm going to draw the prostate for you, its outline. And then right there snuggled up against the midline is a slightly brighter area on the diffusion image in an area that we're now going to map out as PZPM or peripheral zone posteromedial. So you can add that to your armamentarium of descriptors. Another important caveat that's been described in PI-RADS 2.1 is acquisition. The angle of acquisition. For instance, let's pull down the sagittal. You can either acquire with a direct orthogonal, in other words a straight axial like this, or you could be perpendicular to the long axis of the prostate, so like this. Either way is fine. I don't mind. As long as you're consistent specifically with the T2 and the diffusion so that you have a nice match in terms of angle orientation, angle location and slice thickness.
This way, you can scroll up and down together. You're going to see that that doesn't necessarily occur here. Let's pull down our diffusion again. So we have a couple of diffusions, and on the right, a T2. And let's scroll. You may note that the image on the right is not scrolling and there's a reason for that. It's because it's a 3D acquisition with a one millimeter slice thickness thicker, sorry, thinner than the diffusion images. Well, I just violated the rule or caveat I gave you. However, we also acquired to match perfectly with our diffusion, a 2D slice with the same slice thickness as the diffusion images. Now let's scroll and see what happens. Scrolls very nicely together. So why do we have them both? Well, the T2 we have so we can match the scrolling function.
T2 axial imaging also gives you better contrast resolution than 3D thin section imaging. You might say, "Well, why get the 3D? If the 2D has better contrast resolution, why acquire a 3D axial T2?" And the answer is simple. You need it to do mapping and volumetric analysis of tumors for correlation with intraoperative ultrasound and MRI. So it's a necessity in those cases where patients are going to go to surgery and you want to reconstruct a 3D axial acquisition into a sagittal or a coronal. So in our practice, we get both the T2 for diagnosis, for contrast resolution, and to match the scroll when you're scrolling up and down, and the 3D for purposes of mapping in the operating suite. I have more for you on this case so stay tuned for the next vignette.
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Content reviewed: December 29, 2021