0:01

This was a patient who had a left

0:04

hemiparesis as the presenting symptom.

0:07

So when one has a left hemiparesis, we're

0:10

worried about the right motor region

0:13

and, therefore, the right-side vessels.

0:17

So once again, in this case, the patient had a normal CT

0:21

scan—non-contrast CT scan—but because of the clinical

0:25

suspicion of the acute onset of the hemiparesis,

0:28

the patient went on to get the CT angiogram,

0:33

and that's what I'm going to show you right now.

0:36

As with the previous case, usually, I will focus on

0:40

one vessel at a time, going up and down the neck.

0:44

In this case, because it was a left hemiparesis, I'm

0:47

most concerned about the right carotid circulation.

0:50

So as we scroll up from the aorta, we're

0:54

gonna follow the innominate artery and its

0:57

bifurcation to the subclavian artery

0:59

and the right common carotid artery.

1:01

I'm following that right common carotid artery.

1:04

There is some calcified plaque in

1:06

the right common carotid artery.

1:07

There's some soft plaque—this low-

1:11

density area in the right common carotid

1:13

artery—but not a high-grade stenosis.

1:16

I'm now at the carotid bifurcation.

1:18

At this carotid bifurcation, I see

1:20

that there is marked narrowing of the

1:25

right internal carotid artery at the carotid

1:28

bifurcation with a large amount of both

1:31

soft and calcified atherosclerotic plaque.

1:35

At this juncture, what I would do is I would

1:38

go to my magnification, get this really big,

1:41

and now I'm gonna start to measure the degree

1:44

of stenosis based on the NASCET criteria.

1:49

So for this, we're going to use the measuring

1:51

stick, and we're gonna look at the narrowest

1:53

portion of the lumen of this blood vessel,

1:58

the right internal carotid artery, and it

2:00

says it is 1.7 millimeters by NASCET criteria.

2:07

I have to now look at the internal carotid

2:10

artery in a portion of the vessel that is

2:14

not diseased above the area of narrowing.

2:18

So here is my

2:20

right external carotid artery.

2:21

Here is my right internal carotid artery.

2:24

This is a non-diseased segment, and so I am

2:27

now going to once again go to my measuring tool

2:32

and measure the lumen in the normal portion

2:37

of the blood vessel, which is 3.9 millimeters.

2:41

So we would put 1.7 divided by

2:45

3.9 to determine the degree of

2:49

luminal narrowing. So I don't have my calculator with

2:53

me, but I would estimate that to be about 60% narrowing.

2:57

As we follow the blood vessel upwards, we come to the

3:04

petrous internal carotid artery, we come to the cavernous

3:08

carotid artery, and in the cavernous carotid artery, if we're

3:11

comparing the lumen of the right internal carotid artery

3:14

to the lumen of the left internal carotid artery

3:17

in its cavernous portion, there are areas of stenosis.

3:20

Look at this size versus this size, and you can tell

3:24

that there is stenosis, in this case, greater than 50%.

3:28

And I would report that.

3:30

And then we come to the paraclinoid

3:33

internal carotid artery, and then the

3:35

supraclinoid internal carotid artery.

3:38

And what we see is absence of flow

3:42

in the M1 segment of the right middle cerebral artery.

3:48

So here we have this faint view of—here's normal

3:51

contrast in the distal internal carotid artery.

3:54

Here we have absence of contrast.

3:56

We'll compare that with the contralateral side,

3:59

and we see that the patient has a clot in the

4:04

right middle cerebral artery distribution.

4:06

Nonetheless, we do see blood vessels

4:09

in the Sylvian fissure once again,

4:11

thought to be due to collateral flow, and

4:14

those collaterals are doing a very good job.

4:16

They're almost analogous to the left

4:17

side, where we have a normal blood vessel.

4:20

So now we've looked at the right common carotid artery.

4:24

I would do the same for the left side.

4:27

So here we have the left common carotid artery origin.

4:30

We come up the neck.

4:31

There's a little bit of

4:32

calcified atherosclerotic plaque.

4:34

There's a little bit of soft plaque.

4:35

Here we are at the carotid bifurcation.

4:37

We want to window this,

4:41

so we can see the lumen here.

4:42

Here's the lumen.

4:44

Here's calcified plaque.

4:46

Here is soft plaque.

4:48

Here's an area of narrowing.

4:50

We would go ahead and magnify once again,

4:54

and then measure the luminal narrowing.

4:59

This measures 1.6 millimeters.

5:03

We then go up to the normal

5:07

carotid artery, cut in cross-section, which would

5:10

be here, and then we would measure that vessel.

5:16

There's a little bit of blurriness to

5:17

this because I'm using the thick sections.

5:20

I would normally do this on the thin sections

5:22

so that the walls would be a little bit

5:23

more clear, but this is, uh, 0.51. So,

5:28

0.16 divided by 0.51—

5:32

it's gonna be effectively a 32%

5:34

narrowing, which is 68% stenosed.

5:38

And then follow that blood vessel up the petrous portion,

5:42

the cavernous portion, which looks pretty clean,

5:45

particularly when we compare it to the right side.

5:49

And then the M1 segments as well.

5:52

And again, for the, uh, interest of time, we

5:55

won't go through the vertebral arteries.

5:58

Here are the intracranial portions of the vertebral

6:00

arteries, with a little bit of atherosclerotic plaque.

6:03

The next thing that you wanna do is you wanna

6:05

look again at the MIP images, and the MIP images

6:10

on the coronal plane are what I like the most.

6:12

Here, I get to see the anterior

6:14

cerebral arteries very nicely.

6:15

I get to see the left A1 and M1

6:19

segment of the left internal carotid artery.

6:22

Here, I have the right side where we

6:24

have all that atherosclerotic plaque.

6:26

So here's the atherosclerotic plaque in the

6:28

cavernous internal carotid artery with the area of

6:31

stenosis, and then we are missing the M1 segment.

6:35

We have a thin A1 segment on the right

6:38

side, but nonetheless, as you see, we, we do

6:41

have pretty good Sylvian branch collaterals here.

6:44

So maybe this patient, again, will have the frontal

6:48

lobe and the temporal lobe spared of an infarction.

6:51

Here is our vertebrobasilar artery junction.

6:55

Nice looking.

6:57

Little bit of atherosclerosis in the left

7:00

V4 segment. Right V4 segment

7:03

looks good.

7:04

Here's the basilar artery, which looks pristine.

7:06

Again, I would look at this on the axial

7:09

plane as well as the coronal plane.

7:11

This shows the absent M1 segment.

7:15

Nice looking M1, little bit of

7:17

atherosclerosis on the left M1.

7:19

And good looking posterior cerebral arteries,

7:21

good looking anterior cerebral arteries.

7:23

I do the same on the sagittal MIP.

7:26

Looking at the pericallosal artery, the A1, the

7:30

anterior cerebral arteries here—they all look fine.

7:35

Basilar artery looks fine.

7:36

Posterior cerebral artery looks fine.

7:39

Posterior cerebral artery.

7:40

A little bit of irregularity here on

7:42

the left side, and then continuing.

7:46

Into the middle cerebral arteries.

7:47

This is the diseased side, the right side, with

7:52

the middle cerebral artery, Sylvian branches.

7:54

Here's the left side, brighter-looking vessels because

7:57

there's more flow going through them, in part because of

8:00

the cavernous carotid artery stenosis on the right side.

8:03

So here's the normal left side.

8:05

Looking at any branch narrowings, a little

8:07

bit of atherosclerotic change here.

8:10

And then on the diseased side, not as well filling,

8:14

but not as dense contrast.

8:18

And here is our ratty-looking cavernous internal

8:23

carotid artery here, with atherosclerotic changes.

8:27

So in summary, on this, uh, on this case, we

8:32

have, uh, approximately 60% stenosis at the

8:37

right common carotid artery bifurcation.

8:41

We have approximately 68% stenosis at the

8:45

left common carotid artery bifurcation.

8:48

We have high-grade stenosis of the right cavernous

8:52

internal carotid artery with a clot in the

8:55

right M1 segment of the middle cerebral artery.

8:59

And all this is important because remember that

9:01

the interventionalist is going to have to cross

9:04

those areas of narrowing in order to get to do the

9:07

thrombectomy—has to go through the 60% stenosis

9:10

at the carotid bifurcation on the right, has to go

9:13

through the high-grade stenosis in the cavernous carotid

9:15

artery, with all that plaque, to get to the thrombus.

7:39

Posterior cerebral artery.

7:40

A little bit of irregularity here on

7:42

the left side, and then continuing.

7:46

Into the middle cerebral arteries.

7:47

This is the diseased side, the right side, with

7:52

the middle cerebral artery, Sylvian branches.

7:54

Here's the left side, brighter-looking vessels because

7:57

there's more flow going through them, in part because of

8:00

the cavernous carotid artery stenosis on the right side.

8:03

So here's the normal left side.

8:05

Looking at any branch narrowings, a little

8:07

bit of atherosclerotic change here.

8:10

And then on the diseased side, not as well filling,

8:14

but not as dense contrast.

8:18

And here is our ratty-looking cavernous internal

8:23

carotid artery here, with atherosclerotic changes.

8:27

So in summary, on this, uh, on this case, we

8:32

have, uh, approximately 60% stenosis at the

8:37

right common carotid artery bifurcation.

8:41

We have approximately 68% stenosis at the

8:45

left common carotid artery bifurcation.

8:48

We have high-grade stenosis of the right cavernous

8:52

internal carotid artery with a clot in the

8:55

right M1 segment of the middle cerebral artery.

8:59

And all this is important because remember that

9:01

the interventionalist is going to have to cross

9:04

those areas of narrowing in order to get to do the

9:07

thrombectomy—has to go through the 60% stenosis

9:10

at the carotid bifurcation on the right, has to go

9:13

through the high-grade stenosis in the cavernous carotid

9:15

artery, with all that plaque, to get to the thrombus.

9:19

All this is important information.

9:21

You'll note on this case, just in final, that we do

9:26

additional MIP images of the carotid bifurcations in

9:29

order to have a better sense of the degree of stenosis

9:34

in a three-dimensional plane.

9:37

So here is our left side—this is the left internal

9:41

carotid artery, where we called 68% stenosis.

9:45

Here is the right side, where we called 60% stenosis.

9:50

Based on this, I would go back and remeasure

9:53

and make sure that there isn't a higher

9:54

grade stenosis in this patient. And we have

9:58

additional MIP images of the vertebral arteries.

10:02

Looks like there's an area of narrowing in the V2

10:05

segment of the vertebral artery in this case.

10:09

So this was the right side.

10:11

That stenosis that I referred to as high grade

10:13

is actually in the internal carotid artery.

10:16

So, go back and remeasure.

10:18

So, uh, a very nice-looking, uh, example

10:23

of a CTA showing atherosclerotic disease at

10:26

the carotid bifurcations, as well as in the

10:30

right cavernous internal carotid artery, with

10:32

an associated clot in the right M1 segment.