0:01

So here we have a patient that presented

0:02

with right-sided hearing loss.

0:04

Now, what did this patient present with

0:06

right-sided symptoms? Well,

0:07

obviously there's a mass involving the

0:09

right cerebellopontine angle.

0:11

But remember the things that we

0:12

talked about in the past.

0:13

The main purpose of imaging is to show the anatomy.

0:16

And when we do our anatomy just right,

0:18

we want to be able to see the four nerves in the

0:20

internal auditory canal. In this particular case,

0:23

we can see the anterior pituitary.

0:25

This is our facial nerve that's located right there.

0:28

And then if you're at the level of the facial nerve,

0:30

then this is our superior vestibular nerve.

0:32

And we can see as they extend laterally,

0:35

it runs into and is compressed by this large

0:39

right cerebellopontine angle mass.

0:41

So we see a cerebellopontine angle mass.

0:43

The next step that we want to do is how

0:45

do we analyze this? Well, number one,

0:47

we look at the internal characteristics,

0:49

we look at the signal, and on the T2-weighted

0:52

sequences we can see that the signal is very

0:54

similar to the adjacent brain.

0:56

Number two,

0:57

we can see that this overall signal within

0:59

this mass is homogeneous. Remember,

1:02

schwannomas can contain areas of calcification,

1:05

sometimes they can contain areas of hemorrhage and

1:07

they can be a little bit heterogeneous as we saw

1:10

in a couple of vignettes on the schwannomas.

1:13

Rather this is more homogeneous.

1:15

The next thing that we want to do is look

1:17

at the T1-weighted sequences.

1:18

And when we look at the non-contrast

1:20

T1-weighted sequences,

1:21

we can see that the signal is very

1:23

similar to the adjacent brain.

1:25

And this is what we mean by isointense

1:27

to the adjacent brain. Also,

1:29

when we look internally we can see the stellate

1:32

areas of low signal within this mass.

1:35

And this area of low signal could represent stellate

1:38

areas of fibrosis or they could also

1:41

represent hypervascularity.

1:43

And we remember that meningiomas can be

1:45

hypervascular. When we give contrast,

1:48

we can see that this lesion is very avidly

1:51

enhancing, homogeneously. It's not heterogeneous,

1:55

but very homogeneously enhancing.

1:57

And when we look at the axial images we can see that

1:59

the interface of this mass with the adjacent dura is

2:03

very obtuse. And this is the classic dural tail.

2:06

If we look at the coronal images,

2:08

here's another example of the dural tail,

2:11

both superiorly and inferiorly. Remember,

2:14

the dura and the meninges are directly

2:16

adjacent to the skull base.

2:17

The meningiomas arise from the meninges and

2:20

therefore it's going to have

2:21

a very smooth transition.

2:23

Now there is a little bit of a component extending

2:26

into the internal auditory canal.

2:28

You shouldn't be surprised by this.

2:30

Why? Because the internal auditory canal is lined

2:33

by meninges. So anywhere you have meninges,

2:36

you can have meningiomas.

2:37

But realize that the vast majority of this

2:39

is in the cerebellopontine angle.

2:41

It's homogeneously enhancing and the signal

2:45

characteristics are isointense to the adjacent

2:47

brain. So therefore the diagnosis is a meningioma.

2:51

And we should be able to clearly separate this

2:54

and differentiate this from a schwannoma.