@TheAJNR 2/Everyone knows about the spot sign for intracranial hemorrhage
It’s when arterial contrast is seen within a hematoma on CTA, indicating active
extravasation of contrast into the hematoma.
But what if you want to know before the CTA?
@TheAJNR 3/Turns out there are non-contrast head CT signs that a hematoma may expand that perform similarly to the spot sign—and together can be very accurate.
How can you remember what they are?
@TheAJNR 4/If you are wondering if a hematoma will expand, look for the same features as the
most expansive thing in the universe: a black hole.
There are many signs, but 3 best are also seen w/black holes
@TheAJNR 5/First is the blend sign
Here, part of the hematoma has a different attenuation, meaning different age blood & thus active bleeding
It looks like a halo & black holes have halos in the event horizon!
@TheAJNR 6/Next is the black hole sign
Here, regions have very low density, indicating unclotted blood similar to water density.
If blood is still flowing like water, then hematoma may expand
Black holes obviously have black holes too!
@TheAJNR 7/Finally is the island sign
Here, there are satellite hematomas, indicating multiple regions of bleeding, increasing risk of expansion
Black holes usually have satellites orbiting around them from their gravitational pull!
@TheAJNR 8/In this month’s @theAJNR Tran et al. worked to optimize a deep learning model that could predict hematoma expansion with an AUC of 0.8!
In the future, AI may make all these signs obsolete!!
@TheAJNR 9/Now you know the imaging signs for hematoma expansion—until deep learning can assess it for you!
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