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Here is a patient with

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sinonasal congestion and headache.

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Well, as you can see, we have a mass that is involving

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the maxillary sinus as well as the left nasal cavity.

0:13

It grows through the ethmoid sinus into

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the medial aspect of the left orbit, with

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displacement of the medial rectus muscle.

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And it has aggressive bony erosion from the

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ethmoid sinus into the anterior sphenoid sinus.

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Now, this could be any type of malignancy.

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One of the things that we want to identify, and we've

0:38

already done so, is the involvement of the orbit.

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We wanna identify whether there's intracranial

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extension, which would be along the anterior

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cranial fossa floor, and whether it involves the

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pterygopalatine fossa, as it happens in this case.

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What we see is soft tissue, which is

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in the pterygopalatine fossa here on the

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left side, where there should be fat.

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So let's talk about the different

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potential exits from the pterygopalatine fossa. Medially,

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we have the sphenopalatine foramen, which leads from

1:12

the pterygopalatine fossa into the sinonasal cavity.

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This is how this tumor got into

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the pterygopalatine fossa. Laterally,

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the pterygopalatine fossa goes through here,

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and this is the pterygomaxillary fissure

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laterally, that leads to the masticator space.

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So let me get this synced up here.

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This is the pterygomaxillary fissure

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leading to the masticator space.

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You see that there is a small foramen here.

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This is the Vidian canal.

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You can see that there is soft tissue that is just in

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the anterior-most border of the Vidian canal seen here.

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So this tumor may be extending into

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the Vidian canal, which is one of the

1:57

egresses from the pterygopalatine fossa.

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The next one up and further lateral that we see

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is the foramen rotundum, which is right here.

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Again, we notice that there does appear to be

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soft tissue in our foramen rotundum on this slice

2:16

here, and therefore the tumor has likely spread to

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the maxillary nerve along the foramen rotundum.

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You notice that the foramen rotundum goes back to the

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Meckel's cave region on the left side here.

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The next exit from the pterygopalatine

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fossa is the inferior orbital fissure.

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This is seen on the right side and on the left side.

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There's just a little bit of tissue here

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in the inferior orbital fissure that the

2:44

tumor may be entering through the orbit.

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Now it's got orbital entry through the

2:49

ethmoid sinus, so not as important, but

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there may be perineural spread through the

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inferior orbital fissure as well.

2:57

The clean one here and the soft tissue in that,

3:00

more on the left side.

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As we go further inferiorly,

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we have the two foramina here.

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This is the greater

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palatine foramen.

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This is the lesser palatine foramen. Obviously,

3:12

the larger one being the greater, and the smaller

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one being the lesser palatine foramen, and we

3:17

wanna try to see whether there's tumor in that.

3:20

That's quite difficult to tell.

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On the CT scan, we would rely a

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little bit more heavily on the

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MR scan. You notice that the greater and

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lesser palatine foramina ultimately innervate the

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maxillary teeth and end in the incisive canal,

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the nasopalatine foramen up anteriorly.

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So those are some of the egresses from the

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pterygopalatine fossa into the adjacent soft

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tissues that are at risk in this individual.

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As I mentioned, for perineural spread of

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tumor, particularly for adenoid cystic

3:55

carcinoma, MR is going to be a better study.

3:59

This is our high-resolution

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protocol that you've seen before.

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It has the thin section CISS images,

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which are one millimeter thick.

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It has the VIBE images, which are 0.8 millimeter

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thick, and it has the post-gad VIBE images,

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also 0.8 millimeter thick.

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Here is

4:19

even thinner T2-weighted imaging

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with 0.66 millimeters thickness.

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So we're getting pretty high resolution here.

4:28

So on this—uh, this is actually the STIR image—

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we see the tumor that we saw on the CT scan

4:34

that was growing into the sphenoid sinus, as

4:37

well as the orbit, as well as the pterygopalatine

4:40

fossa, and it's also in the nasal cavity.

4:45

In this situation, you see that it

4:46

has somewhat of a heterogeneous signal

4:48

intensity to it, with little fluid levels.

4:50

I'm not sure whether that was biopsied or

4:53

not, but that signal intensity does not give

4:56

us a good indicator of what the histology is.

5:00

Some people might look at this and think

5:02

this is cerebriform and therefore

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an inverted papilloma.

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I mentioned that sometimes adenoid cystic

5:08

carcinomas are very bright on T2-weighted scan.

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This does not look like one of those.

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However, more important than defining the

5:16

histology is defining the extent of the tumor.

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So on the post-gadolinium enhanced scan,

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although there's quite a bit of motion

5:23

artifact, we can definitely separate

5:25

the tumor from the obstructed secretions

5:27

in the maxillary antrum.

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We can also see that involvement of the

5:32

pterygopalatine fossa with enhancing tumor.

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Here we can see the edge of the Vidian canal.

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We can scroll down, and I mentioned about

5:44

the greater and lesser palatine foramina.

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Here we see enhancement of the greater

5:49

palatine foramen and the lesser palatine foramen.

5:52

We don't see that

5:53

on the contralateral side, and therefore this would

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imply that the tumor has spread inferiorly along the

5:59

greater and lesser palatine foramen, and therefore may

6:02

extend to the palate as far as its perineural spread.

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Here you can see enhancing tissue

6:08

coming to the masticator space.

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This is the temporalis muscle.

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This is the masseter muscle.

6:14

These are the groin muscles down here, and even

6:18

here you can see the spread along the periantral fat

6:22

outside the maxillary antrum, and that would be

6:25

leading from, again, the pterygopalatine fossa.

6:29

Here is our

6:31

Meckel's cave region and the foramen rotundum,

6:34

not as clearly defined as demonstrating tumor,

6:39

but I would be worried about this clump of

6:41

enhancement right along the anterior Meckel's cave

6:45

on the left side.

6:47

You notice that the sphenoid sinus is not enhancing.

6:50

This is inspissated secretions or

6:53

obstructed secretion secondary to the tumor.

6:56

Let's just look at the coronal

6:59

reconstruction of the CISS image.

7:02

Here we see the mass, the obstructed maxillary sinus,

7:07

the involvement of the orbit.

7:09

Now with regard to the involvement of the

7:11

orbit, as long as the periorbita has not

7:13

been violated, the orbit will be spared.

7:16

They will use the periorbita

7:18

as the margin of the tumor.

7:20

Once you start seeing irregular margination

7:23

or anything in the intraconal space, then

7:26

there's a high likelihood that, were they

7:29

to contemplate surgical resection, they

7:31

would have to do an orbital exenteration.

7:34

So here on the CISS image, we can see again

7:37

the involvement of the orbit, the involvement

7:39

of the nasal cavity, the ethmoid sinus, the

7:41

sphenoid sinus, and I don't think it's really

7:44

helpful in this specific case for evaluating

7:47

the involvement of the perineural tissue.