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Case: Basilar Artery Clot on CTA, CT, CTP

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0:01

Remember that in addition to the focal neurologic

0:04

deficits that I've described previously, one of the

0:07

presentations of a stroke is dizziness or vertigo.

0:14

Again, this is a pretty nondescript,

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uh, clinical presentation.

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It can be Ménière's disease, it can be just

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dehydration, but the concern by the clinicians

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is, could this be vertebrobasilar artery

0:29

insufficiency? You'll see VBI (vertebrobasilar artery

0:33

insufficiency) or a brainstem stroke, for example.

0:38

So, this was a patient who had just those symptoms.

0:42

Again, the vast majority of

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these are going to be negative.

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This patient, as we look at the non-contrast CT scan,

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we come into a basilar artery, which seems more dense

0:54

than the internal carotid arteries nearby at the

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tip of the basilar artery.

1:00

And that is this density here.

1:02

Now, once again, I would be reflecting

1:05

more on the thin section images.

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Here is the 347-slice portion.

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And we see that the basilar artery seems to be

1:15

overly bright on multiple sections of this CT scan.

1:20

Assessing for the density of the basilar artery

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when you're surrounded by basal cisterns,

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which are dark, is somewhat more difficult than,

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for example, the M1 segment, which is usually

1:31

with a comparison to the contralateral side.

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With the basilar artery, obviously,

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we only have one of them.

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So, there is a suspicion here.

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Again, when evaluating the patient for stroke,

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the first thing I would do is get an overview of

1:44

the whole patient on the thick section images,

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make sure that there is no hemorrhage,

1:50

which is going to require immediate assessment.

1:53

And then move from there to our

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CTA and our thin section images.

1:58

So, once again, I'm going to show the CTA with the

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thick section images initially, purely for the

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purpose of getting through the case a little bit faster.

2:10

So, here we are down at the aorta, and we'll rapidly

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look at the common carotid arteries together.

2:18

The carotid bifurcations together, they look good.

2:22

There was a little bit of calcification

2:24

here, but no high-grade stenosis.

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And then we have our petrous internal carotid arteries

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looking good, and our cavernous carotid arteries

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with calcified plaque, but no high-grade stenosis.

2:38

On the other hand, let's look at our vertebral arteries.

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So, here's the origin of the right vertebral

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artery, the origin of the left vertebral artery.

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Those look good.

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Their V1 segment, prior to entering

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the spinal canal, looks good.

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The V2 segment within the spinal canal.

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Looks good bilaterally, as it comes out of

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the vertebral bodies and proximal to entering

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the intracranial compartment, our V3 segment.

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Little bit of narrowing here, but nothing high-grade.

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Here we have the intracranial V4

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segment of both vertebral arteries.

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They come together.

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Here is our basilar artery, and whoop!

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Where did the basilar artery flow go?

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This is exactly where we saw the

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hyperdensity of the basilar artery.

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Let me see whether I can just hit my 2

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here and go back to the area where we

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saw that high density was right in here.

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And that's where this vessel

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is no longer showing contrast.

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Here's the basilar, pretty much at the midline.

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Here it is again at the midline.

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Dense on the non-contrast because of a clot.

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Absence of flow because of that clot

3:58

in the mid to distal basilar artery.

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And here we have the posterior cerebral arteries.

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They may be getting flows from posterior

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communicating artery collateral flow.

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So let's look at this on our coronal MIP.

4:13

Again, my favorite, MIP.

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I get to see both of the anterior

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cerebral arteries nicely.

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I get to see the A1 segments and the M1

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segments nicely of the internal carotid artery.

4:26

Here's the distal internal carotid artery.

4:28

Distal internal carotid artery.

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And, uh, uh, I have a segment missing here.

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Left vertebral, right vertebral,

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proximal basilar artery.

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Segment missing before it gets to the basilar tip.

4:43

Here's the posterior cerebral,

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posterior cerebral, superior cerebellar.

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But where is this section right here?

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That's where the clot is.

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Let's look at that on the sagittal recon.

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We have the basilar tip.

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We have an outline of a clot.

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We have the proximal basilar, but we have

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a segment missing in the basilar artery.

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This is an emergency because, obviously,

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the basilar artery supplies the brainstem.

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The brainstem runs breathing and cardiac function,

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as well as lots of ocular motor function and cranial

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nerve function, but we're missing that segment.

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Let's look quickly at the CT perfusion.

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Again, I'm on the phone telling the clinician,

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"Hey, you've got a clot in the basilar artery.

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Call the interventionist if they're not

5:38

already there as part of the BAT team."

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This is the cerebral blood volume.

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This is the

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cerebral blood flow map, and what you're seeing

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is within the brainstem and bilateral cerebellum.

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This blue is not good.

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You want it to be more on the red side.

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And on the TMAX, you have all this.

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Remember the TMAX, we have a six-second.

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So anything longer than six seconds,

6:12

which is delayed, is abnormal.

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In this case, bilateral cerebellar and brainstem

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tissue is in the red zone.

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We don't want that.

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And it also affects some of—these

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are the medial occipital lobes.

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This is the normal signal on the

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TMAX, as you can see in the MCA.

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We want it to be blue and light blue.

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Anything below six seconds is our threshold here.

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In this case, we have all this tissue in the

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vertebrobasilar artery distribution, the

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basilar artery distribution, which is abnormal.

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Now let me see whether I have my analysis.

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So, this analysis package gives us the volume of the

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penumbra, the volume of the infarction, and the amount

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of tissue that is salvageable still after intervention.

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So, this is an excellent example of going

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outside the typical middle cerebral artery or

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internal—the anterior circulation infarcts.

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In this case, we have a posterior circulation

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infarct in a patient presenting with dizziness,

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represented by a clot in the mid to distal basilar

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artery with associated perfusion abnormality in the

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cerebellum and in the brainstem from that clot.

Report

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Vascular

Neuroradiology

Emergency

CTP

CTA

CT

Brain

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