2/On axial temporal bone CT, you cannot see the whole cochlea at once. So let’s start at the bottom. The first thing you come to is the basal turn of the cochlea (makes sense, basal=bottom). On axial images, it looks like a banana. I remember both Basal and Banana start w/B.
3/As you move up to the next slice, you start to see the upper turns of the cochlea coming in above the basal turn. They look like a stack of pancakes. Pancakes are the heart of any breakfast, so they are at the heart or middle of the cochlea on imaging.
4/On this slice showing pancakes, you can see the round window and the round window niche. I remember that this slice is where you can see the round window bc pancakes are ROUND.
5/As you move up, you leave the basal turn behind & see only the upper turns. These no longer look like pancakes bc cochlear scala separate them. Instead they look like a bunch of cherries. I know I’m at the cochlea top when I see cherries bc you always put a cherry on top!
6/Here’s an easy way to remember the order of the appearance of the cochlea. Starting at the basal turn, B is for banana & basal. Bananas can make banana pancakes, so the next slice is pancakes. Finally, you put a cherry on top of the pancakes, so top of the cochlea is cherries.
7/On the coronal plane, you get a sense of the spiral nature of the cochlea. It looks like the spiral of a snail’s shell.
8/Looking closely, you can see eyes of the snail on coronal images.Eyes are right in front of the cochlear snail shell—canal of labyrinthine facial nerve segment going anterior & canal of the tympanic segment coming back. Makes sense that the FACIAL nerve canal would be the EYES
9/So now you know the anatomy of the cochlea, so it won’t just look like the layered rolls of Jabba the Hutt to you. May the force of this knowledge be with you!
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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
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!