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So now we're going to talk about imaging

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the head vessels, CTA of the head.

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And the first thing I'd like to talk

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about are the CTA source images.

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So they're whole brain source images

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they do increase the

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conspicuity of infarction.

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Remember non-contrast CT in the early

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hours is only 45 percent sensitive.

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CTA source images are 75 percent sensitive,

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but they're cerebral blood flow-weighted and

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they tend to overestimate the infarction.

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So you can see in this patient with the

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right-sided weakness and non-contrast

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CT that's normal on the CTA source images,

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you can see some hypoattenuation in

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the left lentiform nucleus and the left

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inferior frontal and parietal cortex.

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So it increases the conspicuity of ischemia.

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And we outlined it here a little bit.

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Uh, this is another patient where we

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outlined the CTA source image abnormality,

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but when we compared it with a DWI, the

0:55

actual core infarct was much smaller.

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So it increases the constipation

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of ischemia, but doesn't tell you

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how much tissue is dead on arrival.

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And then as far as the head vessels, everyone

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should be making these overlapping MIPS.

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We acquire them at 30 millimeters and

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overlap them at five-millimeter intervals.

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You can create them in

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axial planes in one minute.

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And they allow you to scroll the vessels

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easily to find proximal vessel occlusion.

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So here's an example of a left MCA occlusion.

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So, in addition to being able to find the level

1:34

of occlusion, you can assess the collaterals.

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So all of these patients have MCA STEM

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emboli, but they have different collaterals.

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And why are the collaterals important?

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Because the better the collaterals, the

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more slowly the infarct grows and the

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more time you have to open the vessel.

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So we tend to grade the

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collaterals in three ways.

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One are symmetric collaterals.

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You can see this plot here.

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Filling defect is consistent with

1:57

clot, and the collateral vessels

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are even more robust than the.

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Contralateral side.

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So those would be robust collaterals

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with a slowly growing infarct.

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On the opposite side, we have

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order malignant collaterals.

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Here's the MCA stem cutoff

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with an MCA stem embolism.

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You don't have any collaterals on this side.

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You know that infarct is

2:14

going to grow really quickly.

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This patient is probably not going to do that

2:18

well, even if you thrombolyze them early.

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And then in between we have

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Intermediate collaterals.

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We have some collaterals, it's

2:25

not malignant, but they're not the

2:27

same as the contralateral side.

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So, that's how you assess collaterals, and

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this is a graphic from some unpublished

2:38

research that I did a while ago with a fellow.

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And the lower line are the good collaterals,

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so you can see it's 6 hours, the infarct's

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only 30 cc's, that's pretty small.

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The pink line is the malignant collaterals,

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so, At two hours, the infarct's already

2:53

70 or 80 cc's, and the intermediate

2:56

collaterals are somewhere in between.

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So, this just gives you an idea of how

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patients with malignant collaterals,

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how quickly their infarcts grow.

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So, I'm going to show you a couple

3:05

examples and we'll go through some cases.

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So, here's a patient who has their

3:09

MCA stem embolus, hyperdense vessel

3:12

sign, has an aspects of nine, just

3:15

had hypodensity in the left insula.

3:17

Everything else looked normal

3:18

on the non-contrast CT.

3:20

We can see MCA stem clot, good

3:23

collaterals, they're just about

3:25

equal to the contralateral side.

3:28

The vessel was open completely.

3:30

with intra-arterial therapy.

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And you can see the follow-up on

3:33

the diffusion-weighted images.

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It's really a pretty small infarct.

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So early infarct, good collaterals, opened

3:40

up the vessel, small final infarct volume.

3:44

And here's just the opposite.

3:45

Here's a patient who presented with

3:47

right-sided weakness at two hours.

3:50

The non-contrast CT looks

3:52

normal, so the ASPECTS is 10.

3:54

The patient actually had an ICA, type of ICA,

3:57

MCA stem thrombus, which you can see here.

4:00

There's absence of type of ICA and MCA.

4:04

Malignant collaterals, there are no collaterals.

4:06

They opened up the vessel within two hours and

4:09

there was still a huge infarct involving most of

4:11

the MCA territory and some of the ACA territory.

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So with that, we're going

4:16

to show you some cases.

4:18

Thanks.