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/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.
If you don’t know the time of stroke onset, are you able to deduce it from imaging?
Here’s a thread to help you date a stroke on MRI!
2/Strokes evolve, or grow old, the same way people evolve or grow old.
The appearance of stroke on imaging mirrors the life stages of a person—you just have to change days for a stroke into years for a person
So 15 day old stroke has features of a 15 year old person, etc.
3/Initially (less than 4-6 hrs), the only finding is restriction (brightness) on diffusion imaging (DWI).
You can remember this bc in the first few months, a baby does nothing but be swaddled or restricted. So early/newly born stroke is like a baby, only restricted
1/”I LOVE spinal cord syndromes!” is a phrase that has NEVER, EVER been said by anyone.
Do you become paralyzed when you see cord signal abnormality?
Never fear—here is a thread on all the incomplete spinal cord syndromes to get you moving again!
2/Spinal cord anatomy can be complex. On imaging, we can see the ant & post nerve roots. We can also see the gray & white matter. Hidden w/in the white matter, however, are numerous efferent & afferent tracts—enough to make your head spin.
3/Lucky for you, for the incomplete cord syndromes, all you need to know is gray matter & 3 main tracts. Anterolaterally, spinothalamic tract (pain & temp). Posteriorly, dorsal columns (vibration, proprioception, & light touch), & next to it, corticospinal tracts—providing motor