2/Here are 3 lesions, all round and bright and in the region of the foramen of Monro. Can you tell from the images which is a colloid cyst and which may be something else? Choose which one or ones you think are a colloid cyst
Choose which one you think is a colloid cyst
4/In this case it was A. B was a tortuous basilar and C was a cavernoma of the chiasm/hypothalamus that had bled and projected into the third ventricle.
5/Many lesions may mimic a colloid cyst at the foramen of Monro. Below is a list, but it is by no means exhaustive. So with so many mimickers, how can you know when to call a colloid cyst?
6/They say location is everything--especially in colloid cysts. 99% of them are located at the foramen of Monro, so if it isn't at the foramen, be suspicious that it isn't a colloid cyst
7/Another feature that makes it special is actually how few special features it has! It should be very featureless. Many imaging findings we use to characterize lesions (enhancement, calcification, diffusion restriction), should all be absent in a colloid cyst
8/I remember this bc colloid cysts are kind of cousins to other midline congenital cysts (Rathke's cyst & Thornwaldt cyst) & they behave similarly. So if there's a feature that would be weird in a Rathke's or Thornwald cyst (calcs, enhancement), it's weird for a colloid cyst
9/But recognizing a colloid cyst isn't enough. There are important things to mention in your report. You should mention anatomic variants of the septum & fornix that could affect the surgical approach. Also mention low T2 signal, as these cysts can be more difficult to resect
10/Another important issue is where along the 3rd ventricle the cyst extends. Zone 1 is anterior to the mass intermedia, Zone 2 is behind Zone 1 but anterior to the aqueduct, and Zone 3 is behind Zone 2. Zones 1 & 3 are higher risk
11/I hate it when classifications don't go in order. I want Zone 1 to be lowest risk and Zone 3 highest. I hate it when there is a sine wave of risk in the classification
12/But you can remember this by remembering that there are openings at the anterior & posterior 3rd ventricle. So anteriorly you are at risk of obstructing the foramen & posteriorly the aqueduct. Zone 2 is just the zone sandwiched between to the two openings, so it is low risk.
13/So remember, there are mimics of colloid cysts all around. So look at the imaging findings, instead of listening to the siren song!
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1/The 90s called & wants its carotid imaging back!
It’s been 30 years--why are you still just quoting NASCET?
Do you feel vulnerable when it comes to identifying plaque vulnerability?
Here’s a thread to help you identify high risk plaques with carotid plaque imaging
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.
1/I always say you can tell a bad read on a spine MR if it doesn’t talk about lateral recesses.
What will I think when I see your read? Do you rate lateral recess stenosis?
Here’s a thread on lateral recess anatomy & a grading system for lateral recess stenosis
2/First anatomy.
Thecal sac is like a highway, carrying the nerve roots down the lumbar spine.
Lateral recess is part of the lateral lumbar canal, which is essentially the exit for spinal nerve roots to get off the thecal sac highway & head out into the rest of the body
3/Exits have 3 main parts.
First is the deceleration lane, where the car slows down as it starts the process of exiting.
Then there is the off ramp itself, and this leads into the service road which takes the car to the roads that it needs to get to its destination