1/As my attending once said, “If I’ve seen it once, I’ve seen it…well once.”
A 🧵about an interesting case that I’ve seen once in 15 years and never again. #medtwitter #radres #FOAMed #FOAMrad #neurorad #Meded #Neurosurgery #HNrad
2/Pt with history only of diabetes came in with altered mental status. There were these super bright round balls in their ventricles. It looked like a snowman massacre happened, with big round snowballs in the ventricles
3/On MRI, these had intrinsic T1 hyperintensity w/chemical shift artifact--they looked like boba tea pearls floating in the ventricles. Typically, we think of chemical shift w/fat--but these were not fat on the CT!! They did not enhance & otherwise, brain was unremarkable for age
4/The answer is looking you right in the eye! This is intraventricular extension of silicone from a silicone retinopexy. Silicone dissections along the optic sheath into subarachnoid space & ventricles. It is typically asymptomatic. And now you've seen as many of these as me!😉
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1/Asking “How old are you?” can be dicey—both in real life & on MRI! Do you know how to tell the age of blood on MRI?
Here’s a thread on how to date blood on MRI so that the next time you see a hemorrhage, your guess on when it happened will always be in the right vein!
2/If you ask someone how to date blood on MRI, they’ll spit out a crazy mnemonic about babies that tells you what signal blood should be on T1 & T2 imaging by age.
But mnemonics are crutch—they help you memorize, but not understand. If you understand, you don’t need to memorize
3/If you look at the mnemonic, you will notice one thing—the T1 signal is all you need to tell if blood is acute, subacute or chronic.
T2 signal will tell if it is early or late in each of those time periods—but that type of detail isn’t needed in real life
Here's a little help on how to do it yourself w/a thread on how to read a head CT!
2/In bread & butter neuroimaging—CT is the bread—maybe a little bland, not super exciting—but necessary & you can get a lot of nutrition out of it
MRI is like the butter—everyone loves it, it makes everything better, & it packs a lot of calories. Today, we start w/the bread!
3/The most important thing to look for on a head CT is blood.
Blood is Bright on a head CT—both start w/B.
Blood is bright bc for all it’s Nobel prizes, all CT is is a density measurement—and blood is denser (thicker) than water & denser things are brighter on CT
MMA fights get a lot of attention, but MMA (middle meningeal art) & dural blood supply doesn’t get the attention it deserves.
A thread on dural vascular anatomy!
2/Everyone knows about the blood supply to the brain.
Circle of Willis anatomy is king and loved by everyone, while the vascular anatomy of the blood supply to the dura is the poor, wicked step child of vascular anatomy that is often forgotten
3/But dural vascular anatomy & supply are important, especially now that MMA embolizations are commonly for chronic recurrent subdurals.
It also important for understanding dural arteriovenous fistulas as well.