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Image Acquisition DWI

2 min.
Pomeranz, Stephen
Stephen J Pomeranz, MD
Chief Medical Officer, ProScan Imaging. Founder, MRI Online
CME Eligible

Let's talk about the guts of prostate MRI, which is diffusion weighted imaging. It is the diffusion weighted imaging varying the B values that allows you to make the apparent diffusion coefficient map, which is basically a calculation of a series of diffusion weighted images. So what criteria do we need to make this ADC map? We need at least three diffusion weighted images with the following parameters, a low B value set. And what is the B value? The B value is the intensity, slope or strength of the gradients, its ability to measure very subtle differences in diffusivity from one tissue area to the next.

So we want a low B value measurement, zero to 100 seconds per millimeters squared. So 50 works just fine, so does 70, so does 30. Then an intermediate B value set between 800 and 1,000, say 900 is just fine. Now you have those two. What I don't want you to do is then extrapolate the third mathematically with a computer or some algorithm. I want you to acquire the third one. And the third one in which 1,200 used to be an acceptable number, now 1,400 or greater seconds per millimeter squared is the acceptable number for the third B value that allows you to make the ADC map calculation.

So you're going to have something on the order of 50, something on the order of 900, and something on the order of 1,400 or greater, 1,600 is fine, 1,700 is fine, if your scanner can do it. If you want to, you can then litter in or add in some other intermediate B values like 500 or 400, but that's not absolutely necessary. The guts of prostate MRI diffusion weighted imaging for the detection of malignancy. Dr. P out.

LESSON 2, TOPIC 8

Mastery Series: PI-RADS 2.1 Update

Mastery Series

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Content reviewed: December 29, 2021

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