2/ With CSF leaks, everyone knows about brain sagging. But this can happen w/other pathologies, ie Chiari 1. Other findings can be seen on brain MRI in CSF leaks. But what are these findings? Are some findings more suggestive than others? Do more findings = ⬆️suspicion?
3/Dobrocky et al. looked at 9 quantitative & 7 qualitative signs seen on brain MRI in CSF leaks to see which are most important. Depending on type & # of findings, they developed a score to indicate what level of suspicion you should have for a leak. pubmed.ncbi.nlm.nih.gov/30776059/
4/Not surprisingly, they found the best sign for CSF leaks is classic pachymeningeal enhancement. While not always seen, it was seen in > 4 out of 5 leak patients, & almost never in others,unless they had recent LP. Therefore, this sign is worth 2 points on the scoring system
5/Classically, subdural collections are also associated, but these are seen less commonly than pachymeningeal enhancement (~about half of leaks), and other patients may have subdurals for other reasons (ie trauma) and therefore, this is only afforded one point.
6/A newer finding assoc w/leaks is rounding of the transverse sinus. Dural sinuses enlarge to compensate for loss of intracranial CSF in leak pts, & in doing so, their margins go from concave to convex. This was seen in 2/3rds of leak pts & never in others, so it is given 2 pts
7/Another overlooked finding in leak pts is⬇️in the suprasellar cistern around the chiasm. As the hindbrain sinks, eventually the chiasm sinks w/it & the cistern below it is attenuated. If the suprasellar cistern below the chiasm measures less than 4mm, this is worth 2 points.
8/Decrease in the pre-pontine cistern (<5mm) was not commonly seen, but was more than 4x more common in leak patients and was reproducible among readers of the scans, and so it was given 1 point.
9/Similarly, a decrease in the ponto-mammillary distance (<6.5mm between the mammillary bodies and top of the pons on the sagittal images) was also not commonly seen, but 3x more common in leak patients and therefore worth 1 point.
10/Other findings, such as the ponto-mesencephalic angle, attenuation of the quadrigeminal plate cistern, enlargement of the intercavernous sinus, and pituitary contour were not reproducible among readers of the scans and therefore not included in the score.
11/Here is the summary of the points awarded to each finding. The scoring system is classified as follows:
12/ So next time you are looking at a brain MRI for intracranial hypotension, you can feel confident in classifying your suspicion of a CSF leak. Say to them like they say in Billions--you are not uncertain 😉
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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/an introductory thread to MRI.
2/Let’s start w/T1—it is #1 after all! T1 is for anatomy
Since it’s anatomic, brain structures will reflect the same color as real life
So gray matter is gray on T1 & white matter is white on T1
So if you see an image where gray is gray & white is white—you know it’s a T1
3/T1 is also for contrast
Contrast material helps us to see masses
Contrast can’t get into normal brain & spine bc of the blood brain barrier—but masses don’t have a blood brain barrier, so when you give contrast, masses will take it up & light up, making them easier to see.
1/Does your ability to remember temporal lobe anatomy seem, well, temporary?
Or are you feeling temporally challenged when it comes to this complex region?
Here’s a thread to help you remember the structures of the temporal lobe!
2/Temporal lobe can be divided centrally & peripherally.
Centrally is the hippocampus.
It’s a very old part of the brain & is relatively well preserved going all the way back to rats.
Its main function is memory—getting both rats & us through mazes—including the maze of life
3/Peripherally is the neocortex.
Although rats also have neocortex, theirs is much different structurally than humans.
So I like to think of neocortex as providing the newer (neo) functions of the temporal lobes seen in humans: speech, language, visual processing/social cues
@TheAJNR 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.
@TheAJNR 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.
1/Do you get a Broca’s aphasia trying remember the location of Broca's area?
Does trying to remember inferior frontal gyrus anatomy leave you speechless?
Don't be at a loss for words when it comes to Broca's area
Here’s a 🧵to help you remember the anatomy of this key region!
2/Anatomy of the inferior frontal gyrus (IFG) is best seen on the sagittal images, where it looks like the McDonald’s arches.
So, to find this area on MR, I open the sagittal images & scroll until I see the arches. When it comes to this method of finding the IFG, i’m lovin it.
3/Inferior frontal gyrus also looks like a sideways 3, if you prefer. This 3 is helpful bc the inferior frontal gyrus has 3 parts—called pars