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Hello and welcome to Noon conference hosted by MRI online. Noon Conference

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Today we're honored to welcome Dr. Michael Lev for a lecture on advanced

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CT MR imaging for stroke patient treatment selection, state of the art and

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future directions. Dr. Lev is a director of emergency radiology and emergency

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neuro radiology at Massachusetts General Hospital in Boston and a professor

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of radiology at Harvard Medical School. He has been an attending radiologist

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at MGH since 1995 and as a board certified in both internal medicine

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and radiology with a certificate of added qualification and neuro radiology.

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Dr. Lev is an elected fellow of both the American Heart Association and

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the American College of radiology. At the end of the lecture join Dr.

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Lev in a Q&A session where he will answer any questions you may

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have on today's topic. With that being said, we're ready to begin today's

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lecture, Dr. Lev, please take it from here.

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Welcome everyone. I will be speaking today on

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advanced CT MR imaging for stroke patient treatment selection,

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and I'm going to do a little bit of a how to and

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where we are right now, as well as talk about

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future directions. So, these are my disclosures, and I want to let everyone

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know I'm actually speaking live from Geneva, Switzerland, I am at a photon

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counting CT meeting at the large hadron collider at CERN,

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home of the Higgs boson, and I'm here with several of my mass

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general Brigham colleagues as well as over 100 other

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scientists and engineers who are working on this next generation of CT scanning.

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It would be interesting to see over the next couple of years how

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this pans out but I think that I could summarize the whole meeting

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by saying everything that I'm going to be discussing today

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we'll probably be able to do in the future using photon counting CT

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faster at higher spatial resolution, at higher contrast resolution, and

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with the ability to do material decomposition and distinguish

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different tissues, so more to come on that.

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Much of what I'm going to speak about in terms of current state

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of the art and how to can be found in this

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monograph issue paper on stroke code imaging that

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we wrote with Chris Potter and the group.

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And basically, stroke is a clinical syndrome, and we like to divide it

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up into different differential diagnoses and different age groups and the

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cut point for adult versus young adult is about age 40

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in adults, certainly cardioembolic stroke from AFib is very important.

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We're seeing probably fewer and fewer new onset large vessel strokes meaning

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carotid artery extra cranial to intracranial embolus, just because we're

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getting so good at screening for those and then treating them preventively.

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And up to 20% of all strokes fall into the other or uncertain

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category, and a big chunk of those are usually due to disease at the

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great vessel origins. Under the age of 40 when you're looking for stroke,

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you want to look for certain keywords. You're much less likely in the

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young adult and adolescent age group to have Atheromatous causes or A fib

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as a cause of stroke. But if you ever hear the word yoga

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chiropractor weightlifting, then you should definitely be thinking about

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dissection. If you hear about someone who has just taken a 10 hour

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plane flight and stands up as they're getting off and suddenly becomes hemiparetic

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or aesthesic, then think about a DBT with a paradoxical convalesce through

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a PFO. It's almost impossible to predict ahead of time if someone's going

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to go into a fib get turbulent flow cause a clot in the

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left atrium or left atrial appendage and have that clot travel up into

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the brain, but there are some clues on a CT scan,

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if the AP left atrial diameter at the maximum level is about four to

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five millimeters or greater, then there's a pretty good chance you'll be

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in a fib and usually over five, and you're almost certainly going to have

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some type of atrial arrhythmia. There's actually clues to that on plain

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film as well, and probably the most important is the carinal angle. And

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normally the carinal angle is anywhere from 45 to about 90 or 100

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degrees. Certainly if it's much over 100 degrees and flattened out here,

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it means the left atrium is pushing up on the Carina and is

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probably enlarged to the point where atrial fibrillation is possible.

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Now, the single biggest take home message from today's talk is that diffusion

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weighted imaging is the reference standard for acute infarction detection,

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and what that means is that once you see true restricted diffusion and

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something bright on DWI in the setting of an acute onset of a

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clinical deficit, it pretty much is irreversible and even if you were to

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reperfuse that tissue or recanalize that occluded middle cerebral artery

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or anterior cerebral artery or Basilar artery acutely, there probably still

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be some neuronal damage on a follow up scan and

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one to...