Interactive Transcript
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.
© 2025 Medality. All Rights Reserved.