Daniel Oh, MD

Time to go for the jugular when it comes to carotid stenosis! Degree of stenosis isn’t all that matters Here’s cheat sheet you NEED to remember the risky features of carotid plaques Read on for the newest @theAJNR SCANtatistic on carotid stenosis: ajnr.org/content/45/7/934 NASCET isn’t the end of what you need to know—it’s just the beginning. In addition to degree of stenosis, there are features of plaques on imaging that suggest they are prone to rupture & cause strokes. You can remember the high-risk features by remembering that atherosclerosis is influenced by a bad diet—so the features you get when you have a bad diet are the same features vulnerable plaques will show on imaging! High risk features: 🔸Size You get increased size w/outward remodeling of your belly w/a bad diet. Same w/vulnerable plaques—larger plaques with outward remodeling are riskier 🔸Irregularity If you eat a poor diet, you will get constipated & irregular. Same w/vulnerable plaques—irregular plaques are at higher risk 🔸Ulceration Obesity is associated with ulcers. Same w/vulnerable plaques—ulcerated plaques are more vulnerable 🔸Lipid necrotic core If you eat a lot, you get more belly fat or lipid in your core. Same w/vulnerable plaques—plaques with fatty deposits in their core are more vulnerable 🔸Loss of fibrous cap If you eat a lot, your belt can’t hold your fat in anymore & will break. Same w/vulnerable plaques—loss of the fibrous cap holding in the lipid core is a high-risk feature. 🔸Neovascularity Poor diet leads to constipation & hemorrhoids, a sort of neovascularity. Same w/vulnerable plaques—increased vasculature in the plaque & enhancement is a high-risk feature. 🔸Hemorrhage Poor diet & hemorrhoids leads to bleeding. Same w/vulnerable plaques—intraplaque hemorrhage is associated with increased chance of rupture More and more research like the research in this month’s @theAJNR have shown that looking at only degree of stenosis & symptomatology are not enough Now you know all the imaging features that suggest a high-risk plaque beyond the degree of stenosis. Don’t narrow your focus when it comes to carotid narrowing!

Sink or swim! Brain is swimming in CSF! CSF is key for protection, buoyancy, & hormone/waste transport Most know basic ventricular anatomy well, but not subarachnoid anatomy. How many cisterns do YOU know? Here’s a quick guide to the key midline cisterns & what to know for each ▶️Cisterna Magna: 🔸Largest of the cisterns 🔸Contains CN 9-11 & vertebral arteries 🔸Remember this bc the LARGEST cistern contains the LARGEST cranial nerve (vagus) and the two cranial nerves around it ▶️Prepontine cistern: 🔸Contains CN 6 & basilar artery 🔸Remember this bc the shape of the number 6 mirrors the curvature of the anterior pons, where this cistern lies ▶️Chiasmatic cistern 🔸Contains CN 2 & pituitary stalk 🔸Easy to remember bc the CHIASM is CN 2 ▶️Interpeduncular cistern: 🔸Contains CN 3 & mammillary bodies 🔸Remember this bc if you lay the number 3 on its side it looks both like the two cerebral peduncles (where this cistern lies) & well, two mamillary bodies ▶️Quadrigeminal cistern 🔸Contains CN4 & pineal gland 🔸East to remember bc QUAD is the prefix for FOUR ▶️Lamina terminalis: 🔸Contains the ACOMM 🔸Remember this bc the shape of subarachnoid hemorrhage after ACOMM rupture follows this cistern anteriorly Now when you look at cisternal anatomy, you will definitely be able to go with the flow!

1/Asking “How old are you?” can be dicey—both in real life & on MRI! Do you know how to tell the age of blood on MRI? Here’s a thread on how to date blood on MRI! After reading this, when you see a hemorrhage, your guess on its age will always be in the right vein!

Tired of stressing whether a brain tumor is progressing? Wish you had some insurance about calling tumor recurrence? Here’s the cheat sheet you NEED for the best signs of tumor progression! Read on for the newest @theAJNR SCANtastic on tumor imaging: ajnr.org/content/45/4/453 ▶️Tumor progression is like tumor escaping treatment. 🔷Just when treatment thinks it’s got tumor trapped at cliff, tumor is able to get away 🔶Think how you would get away if you were chased to a cliff’s edge---these are same signs of tumor progression: ➡️Jump off into the water: 🔸Tumor heads to the water—the ventricular surface 🔸Subependymal enhancement is very specific (93% sensitivity), but it isn’t commonly seen (38% sensitive). ➡️Cross over the rickety bridge: 🔸Tumor crosses over the brain’s main bridge: the corpus callosum 🔸Callosal involvement is only significant if combined w/multiple foci or crossing midline. ➡️Slide down the rocks: 🔸Spectroscopy looks like a slide down: Increased choline is seen w/recurrence—when combined w/low NAA, it looks like a reverse Hunter’s angle 🔸Increased Cho/NAA or Cho/Cre ratios can suggest recurrence ➡️Run fast & get your red blood hot: 🔸Blood volume is hot on perfusion: high rCBV on perfusion 🔸rCBV hotter than the normal contralateral white matter can be used as a gestalt 🔸Quantitatively, rCBV >1.75 is high suggestive of tumor & rCBV > 1.0 is concerning ➡️Try to sneak away when it’s dark: 🔸Tumor looks dark: Low ADC value (dark on T2) is concerning for tumor 🔸Quantitatively ADC value ≤ 1220 × 10-6 mm2/s is 74% sensitive & 89% specific 🔸I joke, “If the ADC is less than 1000 x 10-6, I am 1000% sure it’s tumor!” Now you know the best signs of tumor recurrence on imaging! Hopefully now you know when tumor progression should make your impression!

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 #tweetorial to help you date a #stroke on MR! #medtwitter #meded #neurotwitter #neurology #neurorad #radres #radtwitter #radiology #FOAMed #FOAMrad

1/If all you know is: To Zanzibar By Motor Car—then you don’t even know half of facial nerve anatomy—literally! Here’s a #tweetorial on the facial nerve anatomy you don’t know! #medtwitter #neurotwitter #neurorad #radres #meded #FOAMed #neurosurgery #neurology #radtwitter