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So this is a case of a patient who

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has dissections, and we're going to

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look at the CTA first, and then look

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at the, uh, MRA and compare them.

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So this patient had a normal head CT, was

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having TIAs with some intermittent left

0:15

sided weakness, and this was the CTA.

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And we're going to just look

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at both carotid arteries.

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So here's the right common carotid,

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and bifurcation looks normal.

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And then you'll notice the Right ICA

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becomes attenuated, and there's a severe

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stenosis, and there's not normal fat

0:37

here, so that could be a dissection.

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It could be non-calcified plaque, and you follow

0:43

up the string sign and the soft tissue density

0:46

all the way to the skull base, and then it's

0:48

still small but a little more normal caliber.

0:51

The intracranial circulation looked normal,

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and then we'll look at the left side.

0:55

The left ICA and common carotid.

0:59

Bifurcation looks normal and then we get closer

1:02

to the skull base and you see some narrowing

1:04

and again that soft tissue density and are these

1:07

dissections, I mean suspicion for dissections

1:10

because it's occurring right at the skull base

1:12

where dissections occur and he doesn't have

1:14

much other atheromatous plaque, but it's hard to

1:17

evaluate what's going on in that soft tissue.

1:19

Um, intracranially, the left ICA

1:22

looks, an MCA looks pretty normal, the

1:24

posterior circulation looks normal.

1:26

So the patient got an MR and

1:30

He did not have an infarct.

1:32

Here's the diffusion weighted imaging just

1:34

showing that there was no obvious infarct.

1:39

I think this is just a little focus of artifact

1:41

up there in the right middle frontal gyrus.

1:43

The rest of his Brain looked

1:46

normal in other sequences as well.

1:47

Here's the FLAIR image.

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contrast-enhanced MRA of the neck.

1:56

So let me show you those images.

1:59

So this is the MRA and we're just going

2:02

to focus on the common carotid arteries.

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So here's the left common carotid artery

2:08

and there's the bifurcation and then you'll

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see as we saw with the CTA, narrowing and

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irregularity of the skull base and it gets.

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It's a pinpoint, so there's a

2:20

critical stenosis, and then as we get

2:23

intracranially, that looks more normal.

2:26

And then on the right side, we'll follow

2:28

up the right common carotid artery.

2:31

And then the bifurcation looks good,

2:35

and then it gets narrow again, and it's

2:40

just a string sign until we get to the

2:42

petrous carotid, where it's still smaller

2:47

compared to the contralateral side.

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So, the question is, what's going on with

2:51

those carotid arteries, the beauty about MR?

2:54

is that we have fat

2:58

saturated T1-weighted images.

3:00

So when we look at the fat-saturated T1-weighted

3:02

images, what we see on both sides nicely is

3:05

this T1 hyperintensity in the walls of the

3:08

vessels, bilaterally, and that is, um, really

3:12

pathognomonic for dissections with subacute

3:16

blood within the false lumina bilaterally.

3:20

So that's really confirming that

3:22

there's dissection and um, both the MRA

3:25

and CTA showed the critical stenosis.

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So MR is very helpful in

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looking at the dissection.

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And then the time-of-flight MRA in the

3:38

head looks normal just like the CT.