Lea Alhilali, MD Profile picture
Sep 19, 2022 19 tweets 7 min read Read on X
1/Need help reading spine imaging? I’ve got your back!
A #tweetorial about the ABCs of reading spine MRs & CTs.
#medtwitter #FOAMed #FOAMrad #medstudenttwitter #medstudent #neurorad #radres #neurosurgery #spine #orthopedics @medtweetorials @stefantigges Image
2/A is for alignment. Normal spinal alignment is perfectly in balance, resulting in the minimal energy needed for erect posture. Even subtle changes in alignment need compensatory changes to maintain posture, resulting in more work/energy expenditure & pain. Image
3/The goals for alignment on imaging: (1) look for unstable injuries & (2) look for malalignment that causes early degenerative change. Abnormal motion causes spinal elements to abnormally move against each other, like grinding teeth wears down teeth—this wears down the spine Image
4/B is for bones. On CT, the most important thing to look for w/bones is fractures. You may see focal bony lesions, but you may not. On MR, it is the opposite—you can see marrow lesions easily but you may or may not see edema associated w/fractures if the fracture is subtle. Image
5/Assess the ligaments w/the bones. Unlike long bones, ligaments in the spine cover along the bones like saran wrap. Anterior longitudinal along the vertebral body front, posterior longitudinal along the vertebral body & posterior ligamentous complex along posterior elements Image
6/On CT, you can infer ligamentous injury from the alignment—if the space is too wide, the ligament can’t be intact. On MR you can see edema in the ligament (suspect ligamentous injury) or focal disruption (see the ligamentous injury) Image
7/C is for canal on CT & cord on MRI. On CT, look at canal contents for any large masses or collections that could compromise the canal. You won’t see it all, but you have to try. On MR, assessing the canal is easy. You can also see the cord itself to check for edema/injury Image
8/D is for discs or degenerative findings. Normal discs should look like a kidney on its side, with a little indentation in the middle just like the renal hilum. Any change to this reniform shape means that there is a disc bulge. Image
9/Normal discs also have a very distinctive appearance on sagittal imaging. You should see a T2 bright disc with a dark nucleus pulposus center. It looks like the cross section of a jelly filled donut Image
10/If you lose that jelly filled donut appearance, and the discs look flatter or darker without a definable center—more like flat pancakes than jelly donuts—then the disc is degenerated. Image
11/Several things can happen to a degenerated disc. First, you can get a bulge. I think of a bulge like gaining weight—you slowly get fatter & loosen your belt. For a disc, the annulus degenerates, gets looser & the disc gets a pot belly—so you lose the renal hilum indentation. Image
12/Next you can get a protrusion. If a bulge is loosening your belt (i.e., the annulus is more lax but still intact), a protrusion is like a hernia. The annulus suddenly tears and disc herniates out. This means it is more focal and can happen more acutely. Image
13/Next is an extrusion. Extrusion is when herniated disc become like toothpaste. B/c it’s squishy like toothpaste, an extrusion can move up or down away from the parent disc. Extrusion base can be smaller than the rest of it bc it can squish through small holes like toothpaste Image
14/Finally is a free fragment. This is when a piece of the extrusion breaks off from the rest of the disc—like when you break off some toothpaste onto your toothbrush. You can see this on imaging bc the fragment is usually a different signal than the parent disc—much T2 brighter Image
15/Besides the disc, you should also look at the facet joints. A normal facet joint looks like a hamburger. When the facet starts to look more like a mushroom than a hamburger, with overhanging osteophytes, that’s when I call it degenerated Image
16/In the c-spine, there are also uncovertebral joints. These are at the lateral vertebral body. Normally they should be smooth. On coronal images, they look like little devil horns. When they start to get osteophytes & look more like moose antlers, then they are degenerated. Image
17/So every spine dictation becomes formulaic, like a mad libs fill in the blank. Go through your ABCs and look for abnormalities in each. When you get to the D, if the study was done for degenerative changes, you should evaluate each level individually. Image
18/At each level, it is also a fill in the blank formulaic dictation. You should assess disc, facets, & possibly uncovertebral joints, looking for the signs we have talked about that show they are degenerated. Then you should say what they are doing to the canal & neural foramina Image
19/So now you know how to approach spine imaging studies in a systematic way—so that your dictations will have all the necessary elements to strike that perfect balance between enough detail and enough brevity. I told you I had your back! Image

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More from @teachplaygrub

Apr 2
1/One important aspect to stroke care is well, ASPECTS.

It’s a simple score system—but it’s important to understand all aspects!

Read on for the latest research on ASPECTS in this month’s @theAJNR SCANtastic!

ajnr.org/content/46/3/5…Image
2/ASPECTS stands for “Alberta Stroke Program Early CT Score.”

It’s meant to replace gestalt-ing what percent of the MCA territory is infarcted.

Instead, it uses a 10-pt score to semi-quantitate the infarcted tissue in the MCA territory on non-contrast head CT Image
3/You can think of it as a score card for the MCA.

For each region of MCA territory NOT infarcted, the pt gets one point—for a highest score of 10, and lowest score of 0 Image
Read 18 tweets
Mar 21
1/Don't fall for the siren song of calling all bright round objects at foramen of Monro colloid cysts.

Like a true siren song, this may be a TRAP!

If you hear the call of colloid—read this first!

Here's a thread about lesions here that can trap you--& how you can avoid them! Image
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! Image
3/In this case it was A!

B was a tortuous basilar

C was a cavernoma of the chiasm/hypothalamus that had bled and projected into the third ventricle. Image
Read 12 tweets
Mar 16
1/Remembering spinal fracture classifications is back breaking work!

A thread to review the scoring system for thoracic & lumbar fractures—“TLICS” to the cool kids! Image
2/TLICS scores a fx on (1) morphology & (2) posterior ligamentous complex injury

Let's start w/morphology

TLICS scores severity like the steps to make & eat a pizza:

Mild compression (kneading), strong compression (rolling), rotation (tossing), & distraction (tearing in) Image
3/At the most mild, w/only mild axial loading, you get the simplest fx, a compression fx—like a simple long bone fx--worth 1 pt.

This is like when you just start to kneading the dough. There's pressure, but not as much as with a rolling pin! Image
Read 13 tweets
Mar 14
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 Image
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! Image
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. Image
Read 25 tweets
Mar 12
1/Do you know all the aspects of, well, ASPECTS?

Many know the anterior circulation stroke scoring system—but posterior circulation (pc) ASPECTS is often left behind

25% of infarcts are posterior circulation

Do you know pc-ASPECTS?!

Here’s how to remember pc-ASPECTS! Image
2/Many know anterior circulation ASPECTS.

It uses a 10-point scoring system to semi-quantitation the amount of the MCA territory infarcted on non-contrast head CT

If you need a review: here’s my thread on ASPECTS: Image
3/But it’s only useful for the anterior circulation.

Posterior circulation accounts for ~25% of infarcts.

Even w/recanalization, many of these pts do poorly bc of the extent of already infarcted tissue.

So there’s a need to quantitate the amount of infarcted tissue in these ptsImage
Read 12 tweets
Mar 10
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 Image
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 Image
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 Image
Read 21 tweets

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