If the patient is symptomatic & the greatest stenosis from the plaque is >70% of the diameter of normal distal lumen, patient will likely benefit from carotid endarterectomy
But that doesn’t mean the remaining patients are just fine!
3/Yes, carotid plaques resulting in high-grade stenosis are high risk
But assuming that stenosis is the only mechanism by which a carotid plaque is high risk is like assuming that the only way to kill someone is by strangulation.
4/Carotid disease not only harms by strangulation (stenosis), but also by serving as a source of emboli
A gun isn’t less dangerous bc it shoots from a distance—similarly, a plaque without stenosis is still dangerous if it causes emboli, even if the harm is from a distance
5/So how can we tell which plaques are high risk for emboli stroke and which are stable?
Well, we need to need to leave NASCET behind and look at the plaque itself for clues
6/We can use carotid plaque-RADS, which has been adapted for CTA, bc that is the modality we are most often evaluating carotid plaques on!
7/Type 1 = no plaque.
This is easy to remember bc the number 1 looks like a smooth straight vessel with no plaque!
8/Type 2 = plaque thickness < 3mm & no signs of vulnerability (ulceration)
You can remember this bc 2 is less than 3 & the curve of the number 2 mimics a smooth, non ulcerated plaque.
9/Type 3 = plaque thickness >3mm or ulceration
Remember 3 is greater than 3!
And the scooped out part of the number 3 looks like scooped out ulceration!
10/Type 4 = plaque hemorrhage or intraluminal thrombus
You can remember this bc the pointy part of the number 4 looks like pointy thrombus pointing into the lumen
11/You can also remember that type 4 is for plaque hemorrhage bc the number four has a hole in the middle—just like the hole blasted in a plaque by intraplaque hemorrhage
12/In this month’s @theAJNR, Saba et al. found that this scoring system was highly reproducible among intermediate & experienced readers.
But like all things radiology—there was a learning curve for inexperienced readers.
13/So go beyond NASCET!
Hopefully, now you’ll never feel vulnerable about vulnerable carotid plaque!
1/My hardest thread yet! Are you up for the challenge?
How stroke perfusion imaging works!
Ever wonder why it’s Tmax & not Tmin?
Do you not question & let RAPID read the perfusion for you? Not anymore!
2/Perfusion imaging is based on one principle: When you inject CT or MR intravenous contrast, the contrast flows w/blood & so contrast can be a surrogate marker for blood.
This is key, b/c we can track contrast—it changes CT density or MR signal so we can see where it goes.
3/So if we can track how contrast gets to the tissue (by changes in CT density or MR signal), then we can approximate how BLOOD is getting to the tissue.
And how much blood is getting to the tissue is what perfusion imaging is all about.
1/”That’s a ninja turtle looking at me!” I exclaimed. My fellow rolled his eyes at me, “Why do I feel I’m going to see this a thread on this soon…”
He was right! A thread about one of my favorite imaging findings & pathology behind it
2/Now the ninja turtle isn’t an actual sign—yet!
But I am hoping to make it go viral as one. To understand what this ninja turtle is, you have to know the anatomy.
I have always thought the medulla looks like a 3 leaf clover in this region.
The most medial bump of the clover is the medullary pyramid (motor fibers).
Next to it is the inferior olivary nucleus (ION), & finally, the last largest leaf is the inferior cerebellar peduncle.
Now you can see that the ninja turtle eyes correspond to the ION.
3/But why are IONs large & bright in our ninja turtle?
This is hypertrophic olivary degeneration.
It is how ION degenerates when input to it is disrupted. Input to ION comes from a circuit called the triangle of Guillain & Mollaret—which sounds like a fine French wine label!
1/I always say you can tell a bad read on a spine MR if it doesn’t talk about lateral recesses.
What will I think when I see your read? Do you rate lateral recess stenosis?
Here’s a thread on lateral recess anatomy & a grading system for lateral recess stenosis
2/First anatomy.
Thecal sac is like a highway, carrying the nerve roots down the lumbar spine.
Lateral recess is part of the lateral lumbar canal, which is essentially the exit for spinal nerve roots to get off the thecal sac highway & head out into the rest of the body
3/Exits have 3 main parts.
First is the deceleration lane, where the car slows down as it starts the process of exiting.
Then there is the off ramp itself, and this leads into the service road which takes the car to the roads that it needs to get to its destination