0:00

So we have another mass involving

0:02

the cerebellopontine angle.

0:03

So one of the challenges now is

0:05

how do we address this mass,

0:07

especially when we see no involvement of the

0:11

internal auditory canal?

0:12

So remember,

0:12

the two things that we talked about before was,

0:15

does the mass enhance?

0:17

Is there a dural tail and is there involvement

0:20

of the cerebellopontine angle?

0:21

So now, we're trying to differentiate essentially between

0:24

a vestibular schwannoma and a meningioma,

0:26

and how do we go about that?

0:28

Well, the first thing that we do is we look at the

0:30

mass and look at the T2-weighted images.

0:32

So now we're going to talk about, if you will,

0:34

the higher level analysis of these images.

0:37

So on the T2-weighted images, meningiomas,

0:40

as we'll see later,

0:41

tend to be isointense to the adjacent brain,

0:44

where schwannomas tend to be a little bit more heterogeneous

0:48

on the T2-weighted sequences.

0:50

So when we look at the internal characteristics of the

0:52

T2-weighted sequences, we can see some areas that are a

0:55

little bit higher signal and there are other

0:58

areas that are a little bit lower signal.

1:01

So it's relatively homogeneous, but not really.

1:04

So one can say that it does have some heterogeneous T2 signal.

1:07

So, let's look at the T1 signal

1:10

pre-contrast, we can see there's low signal, but again,

1:13

not to the extent that we see in the fluid of the fourth ventricle.

1:18

When we look at the contrast enhancement,

1:20

there is no, in this case, extension into the IAC.

1:24

It's just not there. Right?

1:25

So, what are those other characteristics we look for?

1:28

Remember, we look at the relationship

1:31

between the mass and the cerebellopontine angle,

1:33

and we can see very nicely,

1:35

unequivocally, that there is this acute angle and

1:38

that tells us that this is not a dural tail.

1:42

And therefore, when we look at the combination of this

1:46

mass that's enhancing, no dural tail,

1:49

heterogeneous T2 signal,

1:51

despite the fact that there's no extension

1:54

into the internal auditory canal,

1:56

this, again, was a schwannoma involving the 7th-8th nerve

2:01

complex and probably arising from the cochlear nerve.