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Lea Alhilali, MD

@teachplaygrub

Dec 5

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

Dec 1

1/To call it or not to call it? That is the question!

Do you feel a bit wacky & wobbly when it comes to calling normal pressure hydrocephalus on imaging?

You don’t want to overcall it, but you don’t want to miss it either!

Let me help you out w/a thread about imaging in NPH!

2/First, you must understand the pathophysiology of “idiopathic” or iNPH.

It was first described in 1965—but, of the original six in the 1965 cohort, 4 were found to have underlying causes for hydrocephalus.

This begs the question—when do you stop looking & call it idiopathic?

3/Thus, some don’t believe true idiopathic NPH exists.

After all, it’s a syndrome defined essentially only by response to a treatment w/o ever a placebo-controlled trial.

However, most believe iNPH does exist--but its underlying etiology is controversial. Several theories exist

Read 19 tweets

Lea Alhilali, MD

@teachplaygrub

Nov 21

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

Nov 4

1/The 90s called & wants its carotid imaging back!

It’s been 30 years--are you still on NASCET?

Feeling vulnerable about plaque vulnerability?

This month’s @theAJNR SCANtastic has what you need to know about carotid plaque

ajnr.org/content/46/10/…

2/Everyone knows the NASCET criteria:

If the patient is symptomatic & the greatest stenosis from the plaque is >70% of the diameter of normal distal lumen, patient will likely benefit from carotid endarterectomy

But that doesn’t mean the remaining patients are just fine!

3/Yes, carotid plaques resulting in high-grade stenosis are high risk

But assuming that stenosis is the only mechanism by which a carotid plaque is high risk is like assuming that the only way to kill someone is by strangulation.

Read 13 tweets

Lea Alhilali, MD

@teachplaygrub

Oct 24

1/Having trouble remembering how to differentiate dementias on imaging?

Is looking at dementia PET scans one of your PET peeves?

Here’s a thread to show you how to remember the imaging findings in dementia & never forget!

2/The most common functional imaging used in dementia is FDG PET. And the most common dementia is Alzheimer’s disease (AD).

On PET, AD demonstrates a typical Nike swoosh pattern—with decreased metabolism in the parietal & temporal regions

3/The swoosh rapidly tapers anteriorly—& so does hypometabolism in AD in the temporal lobe. It usually spares the anterior temporal poles.

So in AD look for a rapidly tapering Nike swoosh, w/hypometabolism in the parietal/temporal regions—sparing the anterior temporal pole

Read 16 tweets

Lea Alhilali, MD

@teachplaygrub

Oct 17

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

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Lea Alhilali, MD

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