0:00

Second case the provided history is concerned for

0:03

MCA stroke, of course, that's not adequate. So

0:06

we're going to dig into the chart and find out a little bit more information. So

0:09

it turns out that they're a 28 year old intravenous drug

0:13

user. They've had a recent bout of mitral valve

0:16

endocarditis and there's still on antimicrobial therapy

0:19

for this. They were last known well two hours

0:22

ago. They're in the hospital and the nurse came in and check

0:25

on them and notice new deficits. They had a left-sided hemiplegia

0:28

and a right side of gaze deviation as well

0:31

as confusion their NIH Stroke Scale was assessed at

0:34

12.

0:36

So the what we can learn from this vignette

0:39

so far. Is that even though

0:42

they're in the TPA window, you

0:45

know within three and a half four and a half hours that

0:48

because

0:51

they have this history of endocarditis. There's

0:54

a relative contraindication to giving TPA. However,

0:57

there's still potentially a candidate for mechanical thrombectomy.

1:00

There's still considered within the early window, you know

1:03

less than six hours in terms of candidate C

1:06

for mechanical front back to me. So now we're going to examine our

1:09

CTE Imaging cases starting with

1:12

a non-con at CT as we do in

1:16

every stroke case

1:19

And what we can notice here, I'm going to turn it

1:22

on stroke window just a really accentuate that great white differentiation is

1:25

that we don't have gray white differentiation laws. We

1:28

actually see areas where there's accentuation of the gray white differentiation. That's

1:31

because of the subcort Y matter hypodensity and

1:34

we might consider this phasergenic edema, which is because

1:37

it looks a little swollen and it's limited to the subcortical white

1:40

matter in these right parallelandic region

1:43

as well as this left posterior Temple

1:46

region.

1:48

But actually if we look a

1:51

little closer we might notice that there is subtle right

1:54

differentiation loss at the right basal ganglia.

1:57

You see how the distinction between the sub-inter or

2:00

Y matter of containment is maintaining on the left side, but not really the

2:03

white right side. There's a blurring of the gray white

2:06

Junction. And so there is in this

2:09

indicates a hypodensity of the ptamian part

2:12

of the caudate as well.

2:15

So what aspects score would you get this? I would give

2:18

this an eight based on a loss of caught it if you came in this case.

2:22

So now let's move on to the CT perfusion. We

2:25

see that rapid has segmented a cvf lesson

2:28

30% volume of 21 milliliters is corresponds

2:31

to mostly the white matter of the

2:34

right MCA territory in the right frontal and

2:37

parietal lobes and then there's a larger area

2:40

of TMax elevation greater than six seconds.

2:43

They have segmented 102 milliliters in this

2:46

corresponds to a large region of the rightmost artery

2:49

territory.

2:51

And this kind of gets into the baseball ganglia

2:54

that we saw the subtle hypodensity and non-continent CT

2:57

as well. So this is a case where there's a large mismatch 81

3:00

milliliters mismatch Ratio or

3:03

4.9.

3:06

Take a look at the other parameter Maps. The hypoperfusion index is

3:09

0.4. So borderline terms

3:12

of the adequacy of collaterals here.

3:18

And a relatively good looking aif curve. Now.

3:21

We're going to use that information to inform our

3:24

evaluation of the CT angiogram

3:27

and here we see as expected

3:30

a cutoff of the right and CA M1 segment

3:33

a large vessel occlusion.

3:36

And we're not gonna stop at just looking at

3:39

the mips of the CTA. We're

3:42

also going to look at here the source

3:45

images of the CTA because we still

3:48

have unexplained those areas of asogenic Edema. Right as we

3:51

see this like faint area of enhancement the right pair

3:54

related region corresponding to the area that demon the

3:57

left parietal region. We see a rim in handing abnormality at

4:00

the left posterior temporal and

4:03

parietal region that in

4:06

the context of having endocarditis would

4:09

be suspicious for cerebral abscess. So they have that going on

4:12

in addition to their large vessel occlusion stroke,

4:15

okay.

4:17

so

4:18

so in summary, we have areas of

4:22

age edema aspects 8 we have

4:25

a mismatch. We have a right M1 occlusion.

4:28

And we also have as a kind of almost incidental

4:31

finding left temporal lobe brain abscess

4:34

and maybe another area in the right carrier Atlantic region, so

4:39

What comments do I have to make about this study?

4:44

Number one in the early window CT perfusion

4:47

is not strictly required. Although we

4:50

do obtain it in many cases look for a stroke mimics when

4:53

evaluating candidacy for mechanical thrombectomy.

4:58

The core that we saw in this case relatively small

5:01

is estimated around 21 milliliters, but

5:04

we're going to take a look at what the final chord look like

5:07

on MRI a little bit later. There was a Target mismatch profile

5:10

and remember to look at the CTA Source

5:13

images Bernie incidental lesions. So and this

5:16

patient was treated with aspiration

5:19

thrombectomy. They achieved good reperfusion and

5:22

Tiki grade 3 Flow restoration after a

5:25

single pass and they're neurologic deficits improved in

5:28

any stroke scale of one for minor facial policy.

5:31

So our next study that we're going

5:34

to take a look at is the MRI that's obtained as

5:37

a fall of after thrombectomy. And at this

5:40

time I'm going to pull up the DWI.

5:44

And scroll to the b1000 images

5:47

and we can activate the poll in the situation. Now, I'm

5:50

going to tell you that this area of infarct delineated on

5:53

the DWI affecting the car date and the putamine and a

5:56

little bit of the Globus paladis here amounted to only about

5:59

10 milliliters by segmented out this area. That's hyperintense

6:02

on the DWI just 10 millimeters. And

6:05

remember this CT perfusion estimate of

6:08

the CBF left in 30%

6:11

volume was greater than

6:14

that 20 something milliliters and

6:17

that area that was segmented out on the CBF map

6:20

and the white matter is not really infarctica

6:23

on this post-thrombectomy MRI.

6:26

So the question for you is what is the

6:29

term for when you overestimate the infarct

6:32

on the initial CTP compared to follow up Imaging in

6:35

the fall of gold standard is going to be MRI after your

6:38

intervention.

6:40

And while you're answering that I'm going to point out a couple other

6:43

findings. Here's the little brain abscess and

6:46

the left posterior temporal lobe region. Here's

6:49

that kind of developing brain abscess or you

6:52

know, sequela of septic emboli in the right period Landing

6:55

region and all multiple other small enhancing

6:58

post side that consequence of their,

7:01

you know, endocarditis and septic. Anboli

7:04

you just incidental to this process of the

7:07

right MCA in part, okay.

7:11

So take a take a gander at the

7:14

answer choices. We have Shadow open Umbra ghost core

7:17

Phantom mismatch misery perfusion and

7:20

CBF shading.

7:22

Okay, and we have a florality getting the

7:25

right answer which is Ghost core the other terms. I

7:28

totally made up Shadow penumbra Phantom mismatch misery perfusion

7:31

CBS shading. So this concept of ghost

7:34

core is just the term to mean

7:37

that in that you've overestimated what

7:40

is infarct on your

7:43

CTP?

7:45

So what I mean by this when we look at the CTF

7:48

CTP parameter Maps based

7:51

on CBF lesson 30% We are making an

7:54

estimate on what will progress or

7:57

has already progressed to infarction. It

8:00

is not the gold standard for determining

8:03

what is infarction. That would be DWI, but

8:06

often we don't obtain DWI as

8:09

the first Imaging and that's where CT perfusion comes

8:12

in. Unfortunately CT perfusion. There is some variability and

8:15

a hot on how well it's able to estimate what

8:18

is in fact the infarctic core.

8:22

And we know that this phenomenon of

8:25

ghost core is more common in the

8:28

early hypercute window less than six hours.

8:31

It's relatively more common to see that there's an

8:34

overestimation of what turns out to be the infarcore

8:37

and we see this after the reperfusion therapy

8:40

on the fall of MRI a smaller core than was predicted.

8:45

So that was the case here in summary. This

8:48

was a case of a small stroke with a significant penumbra.

8:51

There were a good candidate for reperfusion therapy by

8:54

mechanical thrombectomy. And to

8:57

remember that the the CDF segmentation's can

9:00

overestimate infarctic particularly in

9:03

the early window.

9:05

So do we have any questions for this kind of

9:08

chat doctor? Dang, do we consider mismatch between CBF and

9:11

TMax without cbv?

9:14

So that's a good question. So so

9:17

far. I haven't had the time to show you

9:20

guys the cbv map but it is good practice to

9:23

look at all of the parameter Maps CBF cbv

9:27

and MTT when looking at

9:30

your stroke cases, so

9:34

In this case, you know

9:38

we can see relatively.

9:44

Maintained areas of cbv and and most

9:47

of this territory but actually decrease cbv in

9:50

that area that we saw was infected in

9:53

the basal ganglia that would confirm our suspicions the MTT.

9:56

We would expect to be elevating that territory and

9:59

sometimes this is more visually striking and even more

10:02

sensitive than the CBF

10:05

and CBB Maps. The MTT is

10:08

often, you know more visually striking. So on your qualitative analysis,

10:11

it's good to look at

10:14

all the parameter Maps together this the CBB

10:17

the CBF and MTT, but the

10:20

parameters that are

10:23

most commonly used to predict what

10:26

is core and what is

10:29

critical hypoperfusion are going to be your CBF and

10:32

your TMax there have been many studies on

10:35

using cbv to predict core but

10:38

somehow the stroke leadership just has coalesced on

10:41

CBF less than 30 as the primary predictor

10:44

of your ischemic Court.

10:47

Got another question in the Q&A box for this

10:50

specific case. Could The increased volume be because

10:53

of vasogenic Edema was included in the

10:56

core.

10:58

In the increased volume because

11:01

of vasogenic Edema

11:04

was included in the court. Well not exactly

11:07

because this volume that

11:10

is being segmented on the CBF. Lesson. 30% Maps is

11:13

really in the white matter of the

11:16

Corona radiata and Central Valley and

11:19

and some of this

11:22

corresponds to the vasogenma and the parallelogic region. So

11:25

yes, I think in part you are correct, but also some

11:28

of this was not really vasogenic edema kind of in the

11:31

more anterior parts of the corona radiata I think

11:34

is

11:37

Perhaps hypoperfused, but did

11:40

not turn out to be infarcted.

11:44

One more question for this case and then we'll move on. How is

11:47

the volume of infarct calculated on MRI?

11:51

So so there

11:54

are two ways to kind of

11:58

practically speaking calculate the volume of infarct on

12:01

MRI

12:04

Number one is you can kind of use the

12:08

kind of a two diameter

12:11

measuring approach. You measure the

12:16

Diameter of the area that's hyperintense on

12:19

DWI and you estimate by the ellipsoid method, you

12:22

know ABC divided by two the approximate volume

12:25

that is affected here. Another way

12:28

is if your packs has a way to

12:31

do a thresholding based segmentation, you

12:34

can ask it to segment everything that looks hyper intense

12:37

in this region.

12:39

Another way is that if this is plugged into some commercial

12:42

software like

12:45

rapid it will take the ADC map and segment

12:48

everything that falls below a certain ADC threshold

12:51

like 620 and it'll give you

12:54

the volume for that. So there are multiple ways to estimate the

12:57

infarct volume on DWI. If

13:00

you're doing it yourself, I would either measure

13:04

or use your packs to segment the areas

13:07

hyperintense on the DWI, or if you can plug into

13:10

commercial software or have your

13:13

technologist send it to Rapid or Vis or

13:16

for instance. They can calculate the regions that

13:19

have a ADC below a certain threshold.