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Parafalcine Meningioma

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0:00

Dr. Laser,

0:01

This is a 43-year-old man with left

0:02

sided weakness and numbness.

0:04

This is a Sagittal 3D T1 image with contrast,

0:07

and we've got a pretty large mass in the brain.

0:10

What's your first impression of the mass?

0:12

So, the first impression of the mass is that it avidly enhances.

0:16

And then looking at the contours of the mass,

0:18

the structures are rounded.

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You can see that the gray matter,

0:22

which is the dark signal,

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the white matter in this case would be the more lighter

0:27

gray signal contours around the lesion.

0:30

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

1:02

it is to document what space the lesion is in.

1:05

So let's call up some other views of the lesion.

1:08

Perhaps the coronal projection might be helpful.

1:11

And I'll bring down the coronal T2.

1:14

I'll give you a Coronal T1 with contrast,

1:17

and I'll bring down an axial non-contrast

1:20

component of the image.

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And now what do you think of the location of a lesion?

1:24

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.

1:31

Why?

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Because of all the different signs that we've talked

1:34

about. For example, the cleft sign, the CSF cleft sign,

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which he's demonstrating right now.

1:40

You have the Cortical buckling and the Cortical

1:43

and white matter buckling sign.

1:45

Right.

1:45

It goes all the way around there,

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but it doesn't circumscribe it.

1:48

Right. It only goes on the outside edge,

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not on the inside edge.

1:51

Correct.

1:52

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,

2:01

cortex is displaced. You have CSF surrounding the lesion,

2:05

all determined that this is an extra-axial lesion.

2:07

Yeah. Here are a few displaced vessels.

2:09

Here's some more CSF.

2:11

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.

2:48

Correct. You've got a nice little dural tail right here,

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which is also part of the diagnosis.

2:52

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.

2:59

Microcystic change very common in these lesions.

3:02

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,

3:58

10 seconds apart dynamic imaging,

4:01

how would the lesion enhance?

4:03

You're married, by the way.

4:05

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.

4:27

They arrive early, they stay late, and they're very dense.

4:30

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.

4:34

But that's a very good summary of

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what meningiomas look like.

4:38

Let's take a look at some of the other projections

4:41

before we log out here together.

4:44

Look at the axial contrast-enhanced image.

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You see a little bit of the dural enhancement.

4:48

I'll blow it up a little bit so you have a nice view

4:50

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.

4:58

It's not invading the brain on the other side,

5:00

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.

5:11

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.

5:37

Let's move on, shall we?

Report

Description

Faculty

Stephen J Pomeranz, MD

Chief Medical Officer, ProScan Imaging. Founder, MRI Online

ProScan Imaging

Tags

Pediatrics

Neuroradiology

Neoplastic

MRI

Brain

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