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This is a patient who had right-sided tinnitus and

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vertigo and hearing loss. On the high-resolution

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T2-weighted CISS imaging,

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what was noticed was that there was asymmetry in

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the signal intensity of the vestibule on the left

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side when compared to the right side, and looked as

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if there was a filling defect within the vestibule

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on the right side compared with the left side.

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Here on the right side,

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we see the lateral semicircular canal.

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And then we see what looks like a soft tissue

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mass within the vestibule on the right side.

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When we look at the post-gadolinium-enhanced scan,

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we come to the vestibule, and the next slice above,

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we see an area of contrast enhancement.

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This is the area of contrast enhancement.

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And you can very faintly see the

1:02

lateral semicircular canal.

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So here you can see the semicircular canal and the

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enhancement in the anterior portion of the

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semicircular canal, the lateral semicircular canal.

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Now, you might ask yourself,

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how do I know that that is enhancement as opposed

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to an area of fat or an area of hemorrhage?

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Well, fortunately,

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you have pre-gadolinium T1-weighted

1:26

scans in this patient.

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Sometimes, we don't do pre-gadolinium-enhanced scans,

1:30

in which case what we have to do is take our

1:33

sagittal scan and reconstruct it in an axial plane.

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So let's just look and see what would happen if we

1:39

were to try that. So here's our sagittal scan.

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It's 5 mm thick slices,

1:45

and we want to move it into the axial plane

1:49

and then go down to this petrous apex,

1:53

to this region,

1:54

and we don't see something bright there.

1:56

So that is what you are required to do if

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you don't have pre-gad T1-weighted scan.

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Fortunately, in this individual,

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the patient had both pre-gad fat sat and

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pre-gad non-fat sat T1-weighted scans.

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And in that same area,

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we do not see the same level of brightness.

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So this is indeed a soft tissue mass that is

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enhancing, not hemorrhage and not fat.

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On the T1-weighted scan without fat sat,

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we're at the same level here,

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and you see that there's no evidence

2:35

of high signal intensity.

2:37

This is the same anatomic area where we are seeing

2:41

the contrast enhancement. And therefore,

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this makes it more likely that this

2:46

represents a schwannoma. Again,

2:49

could this be an inflammatory process with

2:51

focal enhancement of the anterior turn

2:55

of the lateral semicircular canal? It can.

2:58

But to me,

2:59

this looks like it's a little bit expanded.

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And what we can always do is do a follow-up

3:03

study and see whether it persists.