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Thank you everyone for joining me. Today. We're going to take a

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look at a handful of cases that utilize head CT perfusion.

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Now this session is going to be intended for

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the intermediate to Advanced learner somebody who already has

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some fundamental understanding of the concept of CT perfusion

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that we're not going to go through in detail. And

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really this is more focus on a case-based review

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of the possible indications and uses of

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CT profusion both. Well establish and emerging indications

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for CT perfusion and hopefully

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it'll allow you to gain some more confidence with your

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interpretations of brain CT perfusion. So

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let's begin with our first case the provided

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history is stroke like symptoms and I'm sure

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if you're practicing radiologist, you'll understand

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that the provided history is often inadequate in these cases

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that and so we should take every opportunity we can to dig

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a little into electronic medical record find any

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useful clinically relevant information that we can to

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help us with our interpretation and so in this

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As we learned that this patient is 81 years old. They

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have a history of atrial fibrillation. They're not on anticoagulation.

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So that's a stroke risk factor their last

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known well 16 hours ago. And now they're presenting with

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right-sided hemiplegia and a left gaze deviation.

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So with that information we're going to really scrutinize the

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left scribble hemisphere for a causative lesion, and

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they're NIH stroke scales 24, so it's quite high.

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It's likely this is going to be a debilitating large vessel.

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stroke if present

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So the first thing we're going to do is examine our

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non-contrast head CT the first step of any stroke

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Imaging workup to distinguish hemorrhagic stroke

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from ischemic stroke. And once we've excluded intracranial

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hemorrhage, we're going to now focus on where is

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the ischemic stroke?

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How extensive are the early scheme exchanges and

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how do we best communicate the

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location instant of that ischemic change.

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So now is a good time to launch our first poll

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question, which is about how extensive

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is this infarct as expressed

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with the aspect score. So

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I'm going to talk while you guys answer the question

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by first pausing at

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the level of the basal ganglia here to tell

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you that the aspects score is the Alberta Stroke

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Program early CT score for

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expressing the extent of infarct in a middle super artery

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territory stroke. Okay, so that is

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scored on images of a non-con has CT at

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level the basal ganglia and at the level of above the

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basal ganglia. So at the ganglionic level we score

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areas of the cerebral cortex the basal

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ganglia the insula and internal capsule and then

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above the level of easy ganglia. We score multiple areas

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of the cortex here.

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So take a few seconds. Look at the area of high potency

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gray white differentiation loss here and

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come up with your expression on non-con

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head CT. What is the aspects score?

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All right, so it looks like the

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Scores are all over the place. Yeah, a

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plurality chose two and that

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tied with five the correct answer

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here is one and let me tell you why so

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the maximum score you can have when giving

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an aspect stories 10 and

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that means a completely normal head CT without any gray white

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differentiation loss in the FCA territory and you subtract

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a point for each of the following areas that

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are involved at the ganglionic level. So frontal

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curriculum is called the M1 territory. So that's

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lost here M2 territory is the anterior part

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of the temporal lobe that's affected here. And three is

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the posterior part of the temporal lobe and like the lateral

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occipital lobe. So that's affected here.

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The caught it nucleus is another that's

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affected here.

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Part of the putanium is affected here. The

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insular cortex is affected here. The

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internal capsules. The only part of the aspect score that's

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not affected in this situation and then above the basal ganglia

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level. We have the M3. Sorry the

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M for M5 and M6 cerebral cortex. That's

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roughly dividing to thirds this MCA territory

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that are all affected by this ischemic

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stroke in addition to the MCA territory,

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which has an access for of one

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in this case. There's also in Far involving

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the ACA territory. We see this medial part

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of the frontal lobe being involved with this

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loss it very differentiation. So overall this

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is a very large territory inpark involving nearly

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the entire MCA territory sparing some

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of the butane internal capsule and also enviral

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involving a large portion of the ACA territory

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as well.

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So the next step in

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imaging is a CTA and CTP,

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but we can already make a lot of conclusions based on non-con scte

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alone, which is why I wanted to emphasize that

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evaluation and providing an aspect

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score with that regard. So the next

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part of our Imaging evaluation is

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that we're going to look at is our CT perfusion

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and the CT perfusion. We can see

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on the summary map provided by the vendor rapid that

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the cereal blood flow in that left

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Circle hemisphere is very low the CV of

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less than 30% is segmented out at

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a volume of 287 milliliters. And once again, this includes

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the MCA territory the ACA territory sparing

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some parts of the deep kind of

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lenticulous right region.

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Now looking at the TMax greater than six seconds

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math. This is essentially that entire territory as

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well and it probably artifactually counts

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some of the contralateral, you know

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ripe Bridal region. So we're going to you know, mentally

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take off a little bit of this volume when interpreting

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these numbers so your cvf less than 30% is

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going to be your ischemic core your TMax career

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then six seconds gonna be your critical hype

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who perfusion volume and the mismatch

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in between of these and between these they have

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38 millimeters, but that's probably an overestimate is what

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would you you would consider your penumbra or

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tissue at risk that could be salvaged if

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you were to intervene. Unfortunately what

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we can see from these parameters summary Maps is

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that the core is large. It's essentially most of

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the lesserable hemisphere, you know, except the PCA

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territory, and this is a matched defect

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in terms of

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The comparing the TMax the CBF less than 30

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territories.

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Some other things we can derive from these summary Maps we can

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see that there's a hypoperfusion index which is the ratio of

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TMax greater than 10 seconds to tmaxxary than

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six seconds volume. And this is quite High meaning that

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this tissue is severely ischemic greater

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than 0.4 is considered high

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and that indicates that there's poor collateral.

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flow into this hypoperfused territory

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Another thing we can observe on these summary images

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is that there's a flattening of this

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arterial input function on this time attenuation curve. We

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see that it starts going up around 15 seconds and doesn't come

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back down towards Baseline until after 45 seconds. So with

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this curve is greater than 30 seconds, which is

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strongly suspicious for cardiac output failure

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cardiac dysfunction causing

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a widening of this arterial input

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function curve. So that's something that I think is relevant

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to mention because sometimes you may be the first

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to suggest that possibility because the patient doesn't come with

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pre-existing diagnosis of cardiac disease.

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So the

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last thing that we're going to take a look at so in you know

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in summary the CT perfusion shows large

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core essentially matched defect

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for collaterals or cardiac output and now we're

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going to examine the CT angiogram just to

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see what are the

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Vessel deficits that are concomitant with this perfusion deficit

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so as expected there is a cutoff of

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this left MCA at the distal M1 segment. That's

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after giving off an anterior temporal Branch.

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But you know, most of the MCA territory is Downstream of

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this large vessel occlusion. In addition.

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There's a cutoff here of the ACA the

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left ACA right at the a1a2 junction.

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So that accounts for that ACA invark we

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could have predicted all this just based on looking at our CT

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perfusion parameter maps and using that to inform

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our evaluation of the CT angiogram.

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Okay distally, we see

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their it's a relatively decreased density

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of vessels and the distal territory indicating poor

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collateralization. The rapid software

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does highlight this area as suspicious for large

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vessel occlusion. And you know, it has highlighted

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that for us based on this decrease density of blood vessels.

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So back to our slides, we have A2 and

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M1 occlusions on the left. We have believed in collaterals. This

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patient was outside of the TPA window.

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So they were not receiving from lysis. The infarc

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was too large to

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Be a good candidate for mechanical thrombectomy because the

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benefit would not be realized in this situation.

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There's essentially no tissue left

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to save if you were to take out that clot.

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They were admitted to the neurological Intensive Care

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Unit where they underwent intensive care for swell watch

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they receive hyperosmal or therapy. They

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considered how many cranic to me if it was within the goals

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of care. But unfortunately this patient progressed to

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have cerebral swelling herniation. They were

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put on comfort care and died within a few

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days.

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So what we learned from this case, so this is a case of a completed

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stroke. They were within the so called late window

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late hyperacute window. That's 6 to 24 hours after stroke

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on set. But the CT perfusion imaging

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basically showed no penumbra of salvageable tissue

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at risk. They were not a hyperacute

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intervention candidate based on the findings these, you

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know, non eligibility for you know

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mechanical term back to me could be made on a non

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contrast CT alone because they were so obvious and

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that there was a large territory in far

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however, not all cases are as obvious

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and in those cases CT perfusion can help

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I wanted to show you an obvious case just so you can match up the non-con

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CT findings with that of CT perfusion.

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Does anyone have any questions on the first case? If you

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have any questions, please drop them in the chat and we'll try

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to address it after each case.

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If not, we'll move on.