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!
@TheAJNR 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.
@TheAJNR 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/Do you get a Broca’s aphasia trying remember the location of Broca's area?
Does trying to remember inferior frontal gyrus anatomy leave you speechless?
Don't be at a loss for words when it comes to Broca's area
Here’s a 🧵to help you remember the anatomy of this key region!
2/Anatomy of the inferior frontal gyrus (IFG) is best seen on the sagittal images, where it looks like the McDonald’s arches.
So, to find this area on MR, I open the sagittal images & scroll until I see the arches. When it comes to this method of finding the IFG, i’m lovin it.
3/Inferior frontal gyrus also looks like a sideways 3, if you prefer. This 3 is helpful bc the inferior frontal gyrus has 3 parts—called pars
Brain MRI anatomy is best understood in terms of both form & function.
Here’s a short thread to help you to remember important functional brain anatomy--so you truly can clinically correlate!
2/Let’s start at the top. At the vertex is the superior frontal gyrus. This is easy to remember, bc it’s at the top—and being at the top is superior. It’s like the superior king at the top of the vertex.
3/It is also easy to recognize on imaging. It looks like a big thumb pointing straight up out of the brain. I always look for that thumbs up when I am looking for the superior frontal gyrus (SFG)