2/ICA is like a staircase—winding up through important anatomic regions like a staircase winding up to each floor
Lobby is the neck. First floor is skullbase/carotid canal. Next it stops at the cavernous sinus, before finally reaching the rooftop balcony of the intradural space
3/ICA is divided into numbered segments based on landmarks that denote transitions on its way up the floors.
C1 is in the lobby or neck.
You can remember this b/c the number 1 looks elongated & straight like a neck
4/C2 is the petrous or horizontal segment. This is where the ICA gets to the next floor, the skullbase
I remember this b/c the ICA makes a curve forward here, like a swan’s neck--and number 2 has a forward, swan like curve that looks just like the curve of the petrous segment
5/C3 is the lacerum segment—from above foramen lacerum to petrolingual ligament.
It’s easy to remember b/c lacerum comes from the latin word for torn (b/c foramen lacerum is irregular like a tear or laceration)
Number 3 zig zags like a laceration or torn edge, so C3 = lacerum
6/C4 is the cavernous segment
Cavernous segment has the anterior genu. Here, the ICA makes a curve back, so it looks like a knee (genu is latin for knee)
You can remember C4 is cavernous bc the number 4 has a curve back like the anterior genu of the cavernous ICA, like a knee
7/C5 is the clinoid segment—at the ant. clinoid process
Clinoid process gets its name from its sloped shape. It’s from the same latin root as recline (CLIN)
And we all take a break (take five some might say😉) by sitting back or reclining
Take FIVE & reCLINE. C5 is CLINoid
8/C6 is the ophthalmic segment.
I remember this b/c the circle of the number 6 looks like eyes and its curve looks like eyebrows.
So 6 is an eye = ophthalmic
9/C7 is the communicating or terminal segment
You can remember this bc the number 7 looks like the ICA ending & giving off the PCOMM
The number 7 has the shape of a turn off right before the road ends—& the ICA gives off the PCOMM in its C7 segment right before terminating
10/Now you can remember all the segments of the ICA!
Hopefully this will help you to be precise in your localization and siphon away the term “carotid siphon”!!
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1/The 90s called & wants its carotid imaging back!
It’s been 30 years--why are you still just quoting NASCET?
Do you feel vulnerable when it comes to identifying plaque vulnerability?
Here’s a thread to help you identify high risk plaques with carotid plaque imaging
2/Everyone knows the NASCET criteria:
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.
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
3/At its most basic, you can think of the PPF as a room with 4 doors opening to each of these regions: one posteriorly to the skullbase, one medially to the nasal cavity, one laterally to the infratemporal fossa, and one anteriorly to the orbit