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Lea Alhilali, MD

@teachplaygrub

Jul 29 • 9 tweets • 4 min read • Read on X

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1/Talk about bad blood!

Do you know when a hematoma is going to expand?

Read on for month’s @theAJNR SCANtastic on all you need to know about imaging intracranial hemorrhage!

ajnr.org/content/46/7/1…

@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!

Hopefully, now you will know which clot is hot!

ajnr.org/content/46/7/1…

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More from @teachplaygrub

Lea Alhilali, MD

@teachplaygrub

Aug 1

1/They say form follows function!

Brain MRI anatomy is best understood in terms of both form & function.

Here’s a short thread to help you to remember important functional brain anatomy--so you truly can clinically correlate!

2/Let’s start at the top. At the vertex is the superior frontal gyrus. This is easy to remember, bc it’s at the top—and being at the top is superior. It’s like the superior king at the top of the vertex.

3/It is also easy to recognize on imaging. It looks like a big thumb pointing straight up out of the brain. I always look for that thumbs up when I am looking for the superior frontal gyrus (SFG)

Read 12 tweets

Lea Alhilali, MD

@teachplaygrub

Jul 25

1/Time to go with the flow!

Hoping no one notices you don’t know the anatomy of internal carotid (ICA)?

Do you say “carotid siphon” & hope no one asks for more detail?

Here’s a thread to help you siphon off some information about ICA anatomy!

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.

Read 10 tweets

Lea Alhilali, MD

@teachplaygrub

Jul 23

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.

Read 18 tweets

Lea Alhilali, MD

@teachplaygrub

Jul 21

1/Do you know all the aspects of, well, ASPECTS?

Many know the anterior circulation stroke scoring system—but posterior circulation (pc) ASPECTS is often left behind

25% of infarcts are posterior circulation

Do you know pc-ASPECTS?!

Here’s how to remember pc-ASPECTS!

https://x.com/teachplaygrub/status/1587472264764657664

2/Many know anterior circulation ASPECTS.

It uses a 10-point scoring system to semi-quantitation the amount of the MCA territory infarcted on non-contrast head CT

If you need a review: here’s my thread on ASPECTS:

https://x.com/teachplaygrub/status/1587472264764657664

3/But it’s only useful for the anterior circulation.

Posterior circulation accounts for ~25% of infarcts.

Even w/recanalization, many of these pts do poorly bc of the extent of already infarcted tissue.

So there’s a need to quantitate the amount of infarcted tissue in these pts

Read 12 tweets

Lea Alhilali, MD

@teachplaygrub

Jul 2

1/The medulla is anything but DULL!

Does seeing an infarct in the medulla cause your heart to skip a beat?

Does medullary anatomy send you into respiratory arrest?

Never fear, here is a thread on the major medullary syndromes!

2/The medulla is like a toll road.

Everything going down into the cord must pass through the medulla & everything from the cord going back up to the brain must too.

That’s a lot of tracts for a very small territory. Luckily you don’t need to know every tract

3/Medulla has 4 main vascular territories, spread out like a fan: anteromedial, anterolateral, lateral, and posterior.

You don’t need to remember their names, just the territory they cover—and I’ll show you how

Read 18 tweets

Lea Alhilali, MD

@teachplaygrub

Jun 30

1/Time is brain! But what time is it?

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

Read 10 tweets

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