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I'm here with my young, brilliant colleague,

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Dr. Ben Laser,

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and we are looking at a 48-year-old lady

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with some visual problems

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and those visual problems are on which side?

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Little scrolling here and hopefully you figured out

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within a matter of seconds

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that the visual problems are on the left,

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the patient's left or our right.

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The optic nerve looks like a big tube.

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So, one of the challenges that we have

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in a case like this,

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I'll use my drawing tool,

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is with this sort of fusiform enlargement,

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and this is what I mean by fusiform.

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Are we looking at something

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that is intrinsically expanded?

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Or conversely, are we looking at something

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where we have an optic nerve

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and around the optic nerve,

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we've got something sitting around it

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and it's all kind of blending together

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on this pulsing sequence

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which is water weighted,

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but it's not a true T2-weighted image.

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It's more of a steady state free procession,

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which doesn't have terrific contrast resolution.

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So the answer is

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it's very hard to tell on this sequence.

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So, if you're going to make a judgment right here

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you're probably going to come up on the short end

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or you're going to have to guess.

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But we don't guess

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in radiology, we use other pulsing sequences.

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So, what would you do?

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A post-contrast would probably be the best

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sequence to look at

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the characteristics of the lesion.

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And what plane would you use?

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I would either look at a sagittal or

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if you can do an oblique sagittal

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to kind of look through parallel with the orbit.

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So, a lot of people do this

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and that's because they can

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and not everybody can go oblique,

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but most people these days can go oblique.

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And so,

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if you can go oblique, you absolutely should.

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And let's show you what we mean by that.

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So, we're going to go oblique.

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We're going to go absolutely

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balls on parallel to the optic nerve.

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And when we do that,

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this is what we get.

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So, these are both contrast-enhanced oblique images.

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This one over here is the right side,

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this one over here is the left side,

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so this one is on the right orbit

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or optic nerve

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and this one is the left orbit and optic nerve.

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Now the right one, pretty clear-cut.

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We see the optic nerve, this gray structure,

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and some dura around it.

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That's dark, maybe exacerbated a little bit

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or made more conspicuous by some magic angle effect,

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and the CSF, you don't see very well.

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even though there is a little bit of CSF around there

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because it's a T1.

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So, the CSF is going to be kind of dark,

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so that's not visible right now.

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Did a T2, you'd see a little

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thin stripe of high signal around the optic nerve.

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When we go to the abnormal nerve,

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you gotta look at it.

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You gotta really have a little bit of creativity here.

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You gotta say to yourself,

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"Okay, let's do a little scrolling."

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Is this thing that I see,

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this fluffy, irregular, hyperintense enhancing thing,

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is it inside the nerve, blowing the nerve out?

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Or is it around the nerve

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making the margins of the nerve rather fuzzy?

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If you look very carefully,

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there is the nerve right there.

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I'm gonna make it even bigger.

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That's the nerve right there.

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That is a little bit of dural tissue on either side.

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The rest of the tissue around that,

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including this bulky tissue underneath,

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there's a little more of the nerve. Right there.

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There is the nerve,

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there is the tissue around it.

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So, it is a little tram-tracky.

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In other words, what I mean by that is

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you've got the nerve,

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although it's kind of irregular

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now cause it's getting pushed around

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and sometimes it'll

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it'll form what's called the dotted eye sign.

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You know it becomes kind of irregular

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and then is punctuated

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at the very end where it inserts on the sclera.

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So you got the nerve,

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but then around the nerve,

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here's the nerve right there,

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around the nerve, you have this mushy,

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irregular enhancing tissue,

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which I'll make aquamarine blue,

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and you can see it's a little more bulky inferiorly.

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Right there.

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And so the answer in this case is meningioma.

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Another reason that meningioma would be favored here is,

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you look at the T2-weighted image,

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and I believe we have a regular T2 here somewhere.

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Let's see if we've got it.

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We do.

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And you look at this lesion,

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you know an optic nerve glioma,

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you'd like them to have a little bit of heterogeneity, right?

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It's a glioma.

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You know.

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They're not an ordinary bright,

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but this one's like totally grey,

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just like a meningioma would be.

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Kind of smooth gray,

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only slightly heterogeneous lesion.

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So, it's got the perfect

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T2 signal intensity

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on a T2-weighted image for a meningioma,

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much better than it does for a chiasmatic

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or optic nerve glioma.

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What percent of individuals that

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have optic nerve glioma have enough one?

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It's about 15%.

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About that. Yeah, 15 to 20.

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Yeah, 15 to 20.

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And then the converse,

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you know people with NF1 who have optic nerve gliomas,

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a lot of them have pilocytic astro dysplasia,

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the optic pathway.

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And in my experience,

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it's somewhere between 15 and 30%

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will eventually develop some form of

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optic nerve glioma.

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So, this is an optic nerve glioma.

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It looks like it gets back close to the apex.

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We have a matching case that came from the

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from the brain and grew into the apex.

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This one probably came

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directly from the sheath of the optic nerve

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and is growing

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out the back, towards the apex.

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Let's move on, shall we?