Interactive Transcript
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Dr. Laser,
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This is a 43-year-old man with left
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sided weakness and numbness.
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This is a Sagittal 3D T1 image with contrast,
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and we've got a pretty large mass in the brain.
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What's your first impression of the mass?
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So, the first impression of the mass is that it avidly enhances.
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And then looking at the contours of the mass,
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the structures are rounded.
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You can see that the gray matter,
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which is the dark signal,
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the white matter in this case would be the more lighter
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gray signal contours around the lesion.
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So the first thought to myself is avidly enhances,
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and you have the brain Frankmas,
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actually contouring around the lesion.
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And there's no infiltration whatsoever.
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It's very sharply marginated.
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So even though it's kind of hard to tell.
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And at first glance,
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it looks like you might have white and gray
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matter all the way around the lesion,
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it's highly unusual to have a lesion
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this big that's so well marginated.
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So the fact that it's not infiltrating anything at least
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makes you suspicious that it really is outside
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of the brain in an extra-axial space,
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which you've emphasized repeatedly how important
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it is to document what space the lesion is in.
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So let's call up some other views of the lesion.
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Perhaps the coronal projection might be helpful.
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And I'll bring down the coronal T2.
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I'll give you a Coronal T1 with contrast,
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and I'll bring down an axial non-contrast
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component of the image.
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And now what do you think of the location of a lesion?
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Is it intra-axial or is it extra-axial?
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So now, looking at the lesion,
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you can confidently say that this lesion is extra-axial.
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Why?
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Because of all the different signs that we've talked
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about. For example, the cleft sign, the CSF cleft sign,
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which he's demonstrating right now.
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You have the Cortical buckling and the Cortical
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and white matter buckling sign.
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Right.
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It goes all the way around there,
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but it doesn't circumscribe it.
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Right. It only goes on the outside edge,
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not on the inside edge.
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Correct.
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And you can tell that this lesion is actually
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insinuating itself along the Falx.
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So that also is another sign that tells you that this
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is an extra-axial lesion. Vessels are displaced,
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cortex is displaced. You have CSF surrounding the lesion,
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all determined that this is an extra-axial lesion.
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Yeah. Here are a few displaced vessels.
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Here's some more CSF.
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There's a little vasogenic edema around the lesion.
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And does that preclude the diagnosis of an extra
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axial mass? Not at all.
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A lot of the times,
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these meningiomas can cause really severe vasogenic
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edema and reaction inside the brain.
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Parenchyma, sometimes it can cause none.
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It all depends on the type of tumor,
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and the amount of edema can be very profound.
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There are a few theories on that.
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Some people have postulated there's
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microthrombosis of small veins.
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Some people have suggested that there's micro
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ischemic change from compression.
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There are a number of theories on it,
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but the fact that you have moderate and even marked edema
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does not preclude the diagnosis of meningioma.
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Correct. You've got a nice little dural tail right here,
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which is also part of the diagnosis.
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The signal inside is a little bit twinkly,
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a little bit speckly, if you will.
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And that's okay. That doesn't bother me at all.
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Microcystic change very common in these lesions.
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Lipoid degeneration, not so much common.
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Hemorrhage occurs rare to uncommon, but it does occur,
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even though these are very hard, rock-hard, firm lesions.
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You can also see macrocysts inside the lesion.
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And as we stated, microcysts, but also microcalcifications.
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These calcs are noted histologically as psammoma bodies,
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and they can be little speckly areas of hypo and density.
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Not seen so much in this case,
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but that would be another MR.
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Appearance of meningioma. How about the signal?
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How about the signal on T1 without contrast and T2?
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So on T1,
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you notice right away that the lesion looks exactly
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like the brain parenchyma, the gray matter.
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It's iso-intense to the gray matter.
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On T2, the center of the lesion is heterogeneous,
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but the majority of the lesion is also hyper-intense
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or iso-intense to the gray matter.
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This one is an equilibrium phase MRI.
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But if we did a dynamic MRI with very early, say,
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10 seconds apart dynamic imaging,
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how would the lesion enhance?
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You're married, by the way.
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How would it enhance?
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So they call this the mother-in-law lesion.
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It's very early enhancement,
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so it'd be extremely early arterial phase enhancement.
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It comes early and it stays late.
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So even on delayed imaging,
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the lesion will be extremely enhanced and then they're
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very dense. So that's the typical mother-in-law lesion.
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They arrive early, they stay late, and they're very dense.
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I never heard the very dense part,
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but I certainly wouldn't use that on my own
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mother-in-law for fear of reprisal.
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But that's a very good summary of
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what meningiomas look like.
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Let's take a look at some of the other projections
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before we log out here together.
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Look at the axial contrast-enhanced image.
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You see a little bit of the dural enhancement.
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I'll blow it up a little bit so you have a nice view
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of the C plus T1 and the C minus T1.
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This one's a little unusual in that it's
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actually crossing the Falx now.
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It's not invading the brain on the other side,
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it's still extra-axial, pushing over to the other side.
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So this doesn't violate in any way the white
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matter buckle sign or the buckle sign.
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Here's the white matter buckled around the lesion.
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And then, just to summarize,
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you've got a lot of the other signs of meningioma.
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In this case, you've got the CSF clef sign,
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you've got the displaced vessel sign,
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you've got attachment to the Falx cerebri or to the dura.
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You've got a lesion that is iso-
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intense with the gray matter.
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It's a little bit heterogeneous and it is clearly an extra-
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axial lesion. This a giant convexity falx meningioma.
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Let's move on, shall we?
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