0:00

This was a patient who had a palpable abnormality.

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Superficially, in the left side of the face.

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To identify and detect a lesion,

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I usually go with the T1-weighted scans first.

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T1-weighted scans because you have the nice,

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bright outline of fat that is in the parotid gland.

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As well as superficial fat.

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So, as we scroll,

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This patient's scan ends from the skull base downward.

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We come upon a marker which is very helpful to us,

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That has been placed over the palpable abnormality seen

0:37

on the left side. Let's identify the anatomy.

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This is the masseter muscle.

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This is the pterygoid muscle.

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This is the mandible.

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This is the brighter parotid tissue.

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Brighter than muscle tissue,

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But not as bright as the subcutaneous fat.

0:52

You will see that we can see the parotid duct.

0:57

Wharton's duct. I'm sorry.

1:01

My mistake.

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Stenson's duct inserting here into the buccal mucosa.

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And we have our zygomaticus muscle.

1:07

So, our abnormality is here.

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It's somewhat heterogeneous signal intensity.

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Now,

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This is likely the darker signal intensity

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Is likely the abnormality.

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And the intermediate signal intensity is likely the

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Parotid tissue that is encapsulating the mass.

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You can see on the normal right side,

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We have parotid tissue overlying the masseter muscle.

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And then we have Stenson's duct and zygomaticus

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muscle and the buccinator musculature.

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On the T2-weighted scan,

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We see that this mass

1:43

Is homogeneously bright. On T2-weighted imaging,

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We can see the parotid tissue,

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The normal parotid tissue, superficial to it,

1:53

And we see its border with the masseter muscle.

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If we zoom

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Even further.

2:02

Let me see whether I can work the zoom a little bit more

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And slide this over.

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We might even be able to see what some people would call

2:15

The dark signal intensity capsule around the lesion.

2:20

Let's look at the post-gadolinium enhanced scan.

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And

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And has a somewhat peculiar enhancement characteristic,

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Despite the nice bright signal on

2:43

The T2-weighted imaging.

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This may, in part, be a phenomenon of scanning too early.

2:49

But as we come anteriorly here,

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we see that the lesion actually shows good

2:57

enhancement on the more delayed

3:00

coronal image. Let me magnify again.

3:04

Okay, so on the delayed post-gad, it kind of fills in,

3:08

and that is not unusual for a pleomorphic

3:11

adenoma to have it.

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The initial scan shows less enhancement

3:15

than the delayed scan.

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So delayed accumulation of contrast dye is one of the

3:20

characteristic features of a pleomorphic adenoma.

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Now, as it happens, in this case,

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we did do the diffusion-weighted imaging.

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Again,

3:30

these are thicker sections and not as high resolution.

3:34

Overall, there's the lesion on the DWI.

3:39

On our ADC map,

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we can see that it's relatively bright in ADC,

3:46

suggesting higher ADC values,

3:49

which is in keeping with a benign

3:51

tumor of pleomorphic adenoma.

3:54

So a nice demonstration of a pleomorphic adenoma

3:58

of the superficial parotid tissue.

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Overlying the masseter muscle,

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showing one of its characteristic features,

4:04

which is this delay in accumulation of contrast

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between the axial and the coronal

4:12

subsequent imaging,

4:14

as well as bright high ADC indicative

4:19

of a benign neoplasm.