1/Time is brain! So you don’t have time to struggle w/that "stroke alert" head CT
Here’s a #tweetorial to help you with the CT findings in acute stroke #medtwitter #FOAMed #FOAMrad #medstudenttwitter #medstudent #neurorad #radres @medtweetorials #stroke #neurology #Neurosurgery
2/CT in acute stroke has 2 main purposes—(1) exclude intracranial hemorrhage (a contraindication to thrombolysis) & (2) exclude other pathologies mimicking acute stroke. However, that doesn’t mean you can’t see other findings that can help you diagnose a stroke.
3/Infarct appearance depends on timing. In first 12 hrs, the most common imaging finding is…a normal head CT. However, in some, you see a hyperdense artery or basal ganglia obscuration. Later in the acute period, you see the insular ribbon & sulcal effacement
4/Hyperdense artery sign occurs when you see the thrombus in the artery. The thrombus appears hyperdense bc clot is denser than normal flowing blood—& CT is just a measure of density. So an artery filled w/clot will be denser than arteries filled with flowing blood.
5/Bc the hyperdensity you are seeing is clot, there will not be flowing blood in this region on CTA. So the hyperdense artery will be the inverse of the CTA--where there is hyperdensity on non-contrast CT, there will be no density/contrast on CTA—like a negative of a photograph
6/The other sign in the first 12 hours is the blurred basal ganglia/lentiform nucleus. Usually this region is a triangle of low density white matter (ant limb internal capsule, post limb internal capsule, external capsule) surrounding the high density lentiform nucleus
7/In an acute infarct, this triangle becomes blurred. As the lentiform nucleus becomes more edematous, it becomes similar in density to white matter. So instead of clean line between white and gray matter, they look like they are smeared together.
8/The lentiform nucleus is commonly infarcted bc it receives blood from the lenticulostriate arteries that come off of the M1. So unless there is an occlusion more distal than the M1 segment in the MCA, the blood supply to the lentiform nucleus is cut off and it infarcts early.
9/Why do regions become low density when they infarct? This is bc when O2 & ATP run out, Na/K pump stops working. Bc of the osmotic gradient, Na & H20 rush into the cell. More water in the cell = lower density. For every 1% increase in H20 there is a 2.5 HU decrease in density
10/This brings us to our next sign—hypodense regions of brain outside the basal ganglia. If the brain is low density, that means it has run out of ATP and swelled, which means the damage is irreversible. Low density = dead brain = poor prognostic sign.
11/Another region that infarcts early is the insula. This is bc the insula is actually an internal watershed in the MCA territory. It is the watershed between the lenticulostriate arteries and the M2 sylvian branches. So it will infarct relatively early with low blood supply
12/Later you will get sulcal effacement. Normally, the brain should have lots of sulci that look like ice cracks/crevasses along its surface. As more water accumulates in the dead cells, more swelling occurs, and these crevasses become effaced by the swollen brain.
13/So now you know the 5 main signs of acute infarct on CT—remember, if you see these five, soon that brain won’t be alive!

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More from @teachplaygrub

Aug 3
1/ If only there was a way to make hippocampal anatomy memorable!
Here is a #tweetorial of the basics of hippocampal #anatomy that will hopefully stay in your #hippocampus! #medtwitter #FOAMed #FOAMrad #medstudent #neurorad #radres @medtweetorials #Neurology @StefanTigges
2/Its name “hippocampus” comes from its shape on gross anatomy. Early anatomists thought it looked like an upside down seahorse—w/its curved tail resembling the tail of a seahorse. Hippocampus literally means seahorse.
3/In cross section, it has a spiral appearance, leading to its other name, Cornu Ammonis, translated Ammon’s Horn. Ammon was an Egyptian god w/spiraling rams horns. The hippocampal subfields are abbreviated CA-1, CA-2, etc, w/CA standing for “Cornu Ammonis”
Read 14 tweets
Jul 22
1/Remembering spinal fracture classifications is back breaking work!

A #tweetorial to review the scoring system for thoracic & lumbar fractures—“TLICS” to the cool kids! #medstudenttwitter #medtwitter #radres #FOAMed #FOAMrad #neurorad #Meded #backpain #spine #Neurosurgery
2/We’ll talk about the imaging part of TLICS. TLICS scores a fx on (1) morphology & (2) posterior ligamentous complex (PLC) injury. Let’s start w/morphology. W/only mild axial loading, you get the simplest fx, a compression fx—like a simple long bone fx--worth 1 pt.
3/As the axial force grows, this becomes a burst fx with retropulsion of the posterior vertebral body—just as greater force causes more comminution in long bone fxs. A burst is worth 2 points.
Read 10 tweets
Jul 15
1/Is remembering cerebellar anatomy making you dizzy? Need help telling your flocculus from your nodule?
Here’s some help w/a #anatomy #tweetorial on the 9 lobules of the vermis!#medtwitter #FOAMed #FOAMrad #medstudent #neurorad #radres @medtweetorials #neurosurgery @StefanTigges
2/Coming from anterior, the first lobule is the lingula. It sticks out from the front of the vermis & is connected to the superior cerebellar peduncle. I remember this bc it has a very appropriate name—lingula—it looks like a tongue sticking out of the vermis to lick the SCP.
3/Moving clockwise, next is the central lobule. I remember this bc it is positioned exactly how a central lobule should be positioned, in the driver’s seat—where the front seat driver position would be if the vermis was a car—up front, looking out the windshield over the lingula
Read 12 tweets
Jul 12
1/”That’s a ninja turtle looking at me!” I exclaimed. My fellow rolled his eyes at me, “Why do I feel I’m going to see this on twitter soon…”He was right! A 🧵about 1 of my favorite imaging findings & pathology behind it #medtwitter #FOAMed #FOAMrad #medstudent #neurorad #radres Image
2/Now the ninja turtle isn’t an actual sign—yet! But I am hoping to make it go viral as one. To understand what this ninja turtle is, you have to know the anatomy. I have always thought the medulla looks like a 3 leaf clover in this region. Image
3/ The most medial bump of the clover is the medullary pyramid (motor fibers). Next to it is the inferior olivary nucleus (ION), & finally, the last largest leaf is the inferior cerebellar peduncle. Now you can see that the ninja turtle eyes correspond to the ION. Image
Read 11 tweets
Jul 6
1/ “Now listen carefully!” Does the word “tbone” make you think of a tough guy nickname before ear anatomy? Do you know the CT ice cream cone & then nada? Then you need this #tweetorial on tbone anatomy! #medtwitter #FOAMed #FOAMrad #medstudent #neurorad #radres @medtweetorials
2/For the middle ear, I have a rule of 3s. The middle ear is divided into 3 parts and it contains three ossicles. Today we will focus on the ossicles—each of which has 3 parts!
3/The first ossicle you meet when you enter the middle ear is the malleus. It is called the malleus because it acts like a mallet that hits a drum—literally—the ear drum! I think it looks like Dr. Evil’s mini me, with its short body and round bald head
Read 19 tweets
Jun 27
1/Do radiologists sound like they are speaking a different language when they talk about MRI? T1 shortening what?T2 prolongation who?
Here’s a translation w/a #tweetorial introduction to MRI
#medtwitter #FOAMed #FOAMrad #medstudent #neurorad #radres @MedTweetorials #neurosurgery Image
2/When it comes to bread and butter neuroimaging—MRI is definitely the butter. Butter makes everything taste better and packs a lot of calories. MRI can add so much information to a case Image
3/In fact, if CT is a looking glass into the brain—MRI is a microscope. It can tell us so much more about the brain and pathology that affects the brain. So let’s talk about the basic sequences that make up an MRI and what they can show us. Image
Read 22 tweets

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