Imaging in FESS

Introduction to Imaging in Endoscopic Sinus Surgery

I'm gonna be talking to you about imaging and FESS and FESS in endoscopic sinus surgery
and at the end of this discussion, I'd like to be able to say that you can develop an organized approach
to interpreting a sinus CT, go through the potential anatomic sites
and causes for recurrent sinus infections
and recognize those findings
that might increase the potential
for surgical complications.

And Eric Jablonowski is my artist
and has done a lot of the art that I'll be using.

Approach to Sinus CT Interpretation and Dictation

So when I look at a sinus CT, I know
how long it's my dictation's gonna be based on
what the indication was.

If it's from the ER
and it's just rule out sinusitis, in my opinion,
there's really no imaging needed.
That's a clinical diagnosis.
But if it's just rule out sinusitis,
I'm gonna do a pretty quick dictation.

But if it's a pre-op roadmap to plan surgery
or it's from one of the sinus surgeons,
my dictation's gonna be much more thought,
not more thoughtful, but much longer
and more involved than if it is just for sinusitis.

When you dictate sinuses, choose your words very carefully.
We have some
of these patients may have their surgery denied based on
words that radiologists use,
and when, especially when we get to the septum,
I'll show you some words that
that can really result in denials for patient's surgery.

As you've seen, the endoscopic sinus procedure is tailored
and is different for every patient, for every sinus cavity
and from the right and the left side.
So they treat each of these areas independently
and separately, which is why
our dictations should treat each of them differently
and separately and individually, let's go through each
of the sinuses and talk about some of the variations
and some of the things that are helpful
to put in your dictation.

Maxillary Sinus

The maxillary sinus is the first
to form at birth and it's the first to pneumatize.
It fully pneumatizes during the second decade
and it is really divided into separate cells
and separate locations or recesses.
For example, this is the zygomatic recess.
This is the alveolar recess
and this is the area called the palatine recess.

So if I see mucosal thickening, I try to mention
what part of the maxillary sinus there is.
Mucosal thickening, we almost always see the cyst
or polyps down here in the alveolar recess.
Sometimes I don't even mention them
unless they fill more than a third of the sinus.

If I see soft tissue up here on the non-dependent wall
of the maxillary sinus, I'm very careful to mention that.
Rarely do we see a T1 squamous cell
of the maxillary sinus,
but when they do occur,
they often originate up here. So if I
see mucosal thickening on the non-dependent wall,
I'll specifically mention that and mention how thick it is
and whether the floor, the orbit is intact.

I also like to separately mention the uncinate process
and whether it's normal or atelectatic.
And I mention the maxillary sinus ostium.

So my maxillary sinus dictation might go,
the maxillary sinus is well pneumatized and is clear
and the uncinate process in the ostium are normal.
That's how I'll dictate that there are variants, some
of which John addressed.

This is an example of a hypoplastic maxillary sinus
and this is an atelectatic maxillary sinus.
This patient has not had surgery,
but notice how the uncinate process is atelectatic up
against the infra floor of the orbit
and the sinus is completely opacified an ectatic sinus.

Haller Cells

These are the Haller cells
and usually it look at this patient on the right side.
If you find the inferior turbinate, you trace it up
to its insertion on the lateral nasal wall.
That's the way you can always find the uncinate process.
And usually there is no cell
between the inferior medial orbital wall
and the uncinate process,
but occasionally these anterior ethmoid air cells will
develop in pneumatize into the region
of the maxillary sinus ostium.
And those are the Haller cells.

If you forget the term Haller cell
and you're dictating, just say there is an anterior ethmoid
cell located at the maxillary sinus ostium
because that's really all a Haller cell is.

Ectatic Uncinate Process

John talked a little bit about an ectatic uncinate process
and one of the surgical complications.
And that is that in the normal setting,
if you look at this side, the uncinate process is medial
to the lamina papyracea.
If you draw a vertical line from the tip
of the uncinate process, it's medial to the lamina pap.
So the surgeon can do an uncinectomy
and hopefully the medial orbital wall will not be involved in any of the surgical procedure.

On the other hand, with an atelectatic lateral wall
of the nasal cavity
or an atelectatic uncinate process, notice that if you draw
that line, it will be lateral to the lamina papyracea.
And that has definitely been reported in the ENT literature
as a risk factor when the surgeon does an uncinectomy.
So I like to mention whether the uncinate process
is lateralized.

Maxillary Recirculation

He also talked about maxillary recirculation,
and this is what happens with recirculation.
In the old days when patients had sinus surgery
and a hundred percent of them came back with recurrent symptoms, it was often
because the surgeon had done an inferior antrostomy.
This was before we recognized
that the cilia have a very orderly way
of beating the mucus.
It beats it up and out the maxillary ostium.
So if you do an antrostomy down here,
what happens is this diseased mucosa mucus will come out the maxillary ostium
and then recirculate and go right back into the sinus.
And that's the maxillary recirculation syndrome.

As a radiologist, if I see
that perhaps the patient has had surgery in the old days, so to speak,
where they've had an inferior antrostomy,
I'll put that in my dictation.
So the surgeon is aware that that is a potential.

Ethmoid Air Cells

Now the ethmoid air cells are the paired septated cells.
The anterior
and the posterior ethmoids are embryologically different.
The anterior ethmoids, there are many more of them
and they're smaller volume where they're usually just one
to two posterior ethmoids, they're larger
and of course they're just anterior to the anterior wall
of the sphenoid sinus.
Their drainage is also different.
The anterior ethmoids drain into the middle meatus.

Here's an example of a patient
with a normal looking agger nasi cells
and multiple small anterior ethmoid cells here
above the agger nasi.

And it's hard to talk about the ethmoid air cells without
kind of immediately talking about the frontal recess.
And so this is kind
of a segue into discussing the frontal recess.

Frontal Recess and Sinus

It's tough on the coronals, in my opinion,
to find the drainage of this frontal sinus.
How does this sinus drain,
where the sagittal reformations make it so easy
to see the frontal recess?
And let's go through some
of the anatomy in this frontal recess.

The frontal sinus is absent at birth
and it fully pneumatizes in the second decade.
Basically, the frontal sinus is a big anterior ethmoid air
cell and the drainage the drainage is best seen on the
sagittal reformations.
They're often asymmetric and they may be septated.

What I like to do is look for the agger nasi cell,
and I put that in every one of my dictations.
The agger nasi cell is the anterior most ethmoid air cell.
I mention whether the agger nasi cells are symmetric
and I like to turn on the sagittals
and see if they're a prominent or
otherwise unusual agger cell.

On the sagittal images, this is the frontal sinus itself.
This is the anterior bony beak
and this is the posterior aspect
of this area called the isthmus or the frontal isthmus.
And this funnels directly into this area,
which is the frontal recess.
So frontal sinus, anterior bony beak, posterior wall
of the isthmus, and then right into the frontal recess,
notice the variable size
that you can see at the frontal isthmus and frontal recess.

Here's a patient with a very wide
isthmus, and here's a patient.
I've put a little circle there with a very narrow isthmus.

As John alluded to, we don't really talk about the size
of the ostium since this isn't the issue.
It's whether it's physiologically a normal or functioning ostium.
So I wouldn't really mention that this is a narrowed isthmus,
but I might say here
that the bony beak is prominent indirectly hoping the
surgeon will take a look and see that that's a small ostium.

These are our axial source images.
We do our reformations every 2.5 millimeters.
We our standard is to go from right to left
and these are the routine reformations
that we get on our sagittal reformations.

Now the agger nasi cell, again is the anterior most of the ethmoid air cells.
And this is the region of the left agger nasi cell
with the agger nasi cells.
There's a tremendous variation in the cells.
Here's one that's fairly small
and is clearly several millimeters below this bony beak.
Here's a patient with a larger agger cell
and notice how the roof domes up
and meets the under surface of the bony beak
of the anterior aspect of the isthmus.

So a lot of variability
and you'll appreciate that on the coronals as well,
where one agger cell will be much larger than the other.

I find the agger nasi cells by beginning at the tip
of the nose and moving posteriorly.
Very first cell that pops into view is going
to be the agger nasi cell.

There are a variety of variant cells that can occur
above the agger nasi.
If you have one cell above the agger,
that's called a type one frontal cell.
If you have two little cells above the agger,
those are type two frontal cells.
And this is what it looks like on the sagittal.
There is the agger cell
and there are two little cells
that are anterior at the frontal isthmus and recess.

The type two frontal cells, this is
what it looks like on the our CT scan.

An enormous concha does the concha matter.
That doesn't matter. What matters is what it's doing.
And this large concha is resulting in this lateralized
atelectatic uncinate process.
But notice that there's the agger cell
and above it there is one little air cell
that's a type one frontal cell.
And you can see that when the surgeon addresses this area,
he's going to need to take back,
take down the posterior aspect of the agger nasi cell.
If he stops there, he's left this cell, which is there
to further obstruct this frontal sinus outflow tract.
So he will take down the posterior aspect
of both of these cells.

Here's the patient with a two little cells
above the agger nasi.
These are called the type two frontal cells.
If you forget the name nomenclature in this location,
all you have to do is say there are two small cells
pneumatized above the agger nasi
and the surgeon will know what you're talking about.

Sometimes these little cells can pneumatize
above the bony beak
and well into the region of the isthmus,
or they can pneumatize
and be incorporated into the frontal sinus completely.
These are the type three and type four frontal cells.

So here's a patient. There's the agger nasi cell right
there on the sagittal.
Nice look here at the nasal lacrimal duct coming down
to drain beneath the inferior turbinate.
And notice that there's a completely opacified cell here,
which is above the agger
and it's kind of herniated up over this bony beak.
And that's an opacified type three frontal cell.

So this patient doesn't need just run
of the mill endoscopic sinus surgery.
This is a much more difficult procedure endoscopically,
which will require resecting the posterior aspect of
that type three cell.

Here's another patient with a normal agger nasi right there,
a little cell above the agger nasi
and notice the opacification here.
And when you look on your sagittals,
the anatomy makes so much more sense.
There's the agger nasi cell right there, right
behind the nasal lacrimal duct,
and there's that anterior ethmoid air cell,
which is extended up over the bony beak.
And you can see that's where this patient's getting a lot
of inflammatory debris.
And this cell here is the ethmoid bulla.

So that's a type three frontal cell.

If you ever see a opacified frontal sinus,
and it looks like there's a balloon in the sinus,
that's a type four frontal cell.

So this patient has bilateral frontal sinus opacification,
but it's like, what is
that one single area doing in that cell?
And on the axial images, you can see it here,
it's normally pneumatized.
This is the cell right here. It's a type four frontal cell.
It's pneumatized up into the frontal sinus,
and that's a whole different ball of wax when it comes
to sinus surgery.

So this is another patient with a,
it looks like a little air-filled balloon in a completely
opacified frontal sinus.
That is a type four frontal cell.

So agger nasi cell right here, single cell above the
agger nasi type one tiered little cells above the agger nasi type two,
and then cells that pneumatize into the frontal sinus,
the type three frontal cells.

Supraorbital Ethmoid Cells and Frontal Bullar Cells

Now on the lateral aspect, notice that this area
of the frontal recess can have aber
or unusual cells that are coming from the posterior aspect.
And notice that these posterior cells,
their posterior wall is the floor
of the anterior skull base.
And these are called the supra bulla
or frontal bulla cells.

Again, if you forget the name
or your surgeon uses a different nomenclature,
you can simply say there's a pneumatized ethmoid air cell at
the posterior aspect of the frontal isthmus that is present above the level of the frontal ostium.

Here's an example of supra bulla cells, sagittal agger nasi cell
bony beak, frontal sinus outflow tract isthmus right here,
frontal recess, small cell here above this opacified ethmoid bulla, that's a supra bulla cell.

Just so you can see it without the little yellow line.
The supra bulla cell on this,
this patient has an agger nasi cell right here.
It's at the posterior aspect of the frontal isthmus.
Notice that it is extended up into the frontal sinus.
This is called a frontal bulla cell.
If you're not familiar with that standard terminology,
just say it's an ethmoid cell, it's posterior,
it's filling the posterior inferior aspect
of the frontal sinus outflow tract.
And it's at the level of the isthmus.

Supraorbital ethmoid cells are these cells
that look like they're posterior
to the frontal sinus on your axials
and on your sagittal images.
They're pneumatized cells here above the orbit.

Recurrent Disease and Sphenoid Sinus

Okay, this is what recurrent disease looks like.
This is sino nasal polyposis.
Patient has had surgery
and you can see here that he has had widening here
of the frontal sinus outflow track and the frontal recess
and has this polypoid benign looking soft tissue coming out.

The operated site,
sphenoid sinus is the last to pneumatize.
What we're looking for is radiologists.
We wanna make sure the roof of the sphenoid sinus is intact.
Notice that on the sagittal images, that's one
of the best ways to look at the anterior wall
of the sphenoid sinus.

I know many of you in the audience saw
that this patient has a defect here in the roof
of the posterior ethmoids.

Nasal Cavity and Septal Deviation

Finally, the nasal cavity on the anterior most aspect
of your scan, you'll see this nasal septal swell body.
It's often looks very full
and maybe hourglass contour,
and you almost always will see the inferior turbinates kind
of peeking around the inferior aspect of that swell body.

Remember, the nasal cavity is comprised
of three components and ant
or the nasal septum, the anterior cartilaginous.
This bone is part
of the perpendicular plate of the ethmoid bone.
And then this is the vomer.
And when you see a septal deviation,
it's often here at the confluence of the perpendicular plate
of the ethmoid bone and the vomer.

We are very poor at predicting whether a septal deviation is
clinically significant
or if a septal deviation narrows the nasal cavity.
What I say is there either is a septal deviation
or a severe septal deviation.
I'm never try to say mild or moderate
because what we say see on our imaging often does not
reflect what they see in the office.

And as I said, the poor choice of words here can definitely
result in a third party payer denying
payment for surgery.

If I see something like this,
I'll say severe septal deviation, large bony spur,
which is abutting the turbinate,
and that kind of, if this patient has nasal obstruction
symptoms, that should meet any criteria for surgery.

Skull Base Integrity and Lamina Papyracea

Just a last reminder to look at the integrity
of the skull base and the lamina papyracea.
Look at this anatomy here.
Remember, you can find the middle turbinate,
trace it up to its insertion on the skull base.
Medial to that is always the cribriform plate.
And lateral to that is this thin bone called
the lateral lamella.
When this thin bone starts to thicken,
that's the ethmoid roof.

So my standard dictation, I say the cribriform plate,
lateral lamella and ethmoid roof are intact.
Be sure you mention in your dictation if there's a defect
in the ethmoid roof.

Look for these little holes in the
superior lateral wall of the sphenoid sinus.
And of course, always mention whether there is a defect in
the cribriform plate.

Axial images of a defect in the orbital roof
or the ethmoid roof always looks like this.
You'll see nice pneumatized cells on one side
and the brain will look low hanging on the other
and be very suspicious if you see this on an axial
'cause it's likely your coronal
and sagittal will show that skull base defect.

Same case here. Radiologists interpreting.
This was all about this little ostium when this is
the important finding.
Looks like there's a mass here in the roof
of the nasal cavity
and there is, it's the brain.

Lamina papyracea defects always should be mentioned on
your CT scans.
Here's a patient who's had sinus surgery
with a lamina papyracea defect and I usually will measure that
and tell them where it is in the globe.

Surgical Complications and Other Findings

So John went through all these types
of endoscopic sinus surgery.
He talked a little bit about why
patients fail this surgery.
Osteogenesis is one common reason
and if I see anything that looks like this,
like thickened sclerotic sinus walls, I'll put
that in the dictation.
That is osteogenesis.
That is very difficult for the surgeon to handle.

Here's another case of osteogenesis,
very thick sclerotic sinus walls.

Last but not least, step back.
Make sure you're not dealing with the wrong diagnosis.
Here's a patient who'd had sinus surgery
for headaches when he had a colloid cyst.

Structured Dictation Approach

So I usually start with the right side.
Then I go to the left side.
And with each side I talk first about the sinus maxillary
sinus uncinate process and the ostium.
I then turn my sagittals
and I look at the frontal sinus, the frontal recess,
and talk about the agger nasi cell
and if there are any frontal cells above the agger nasi.

The next thing in my dictation are the anterior ethmoids,
which I do kind of lump together.
Then the posterior ethmoids and the sphenoid sinus.
My third paragraph, I talk about the nasal cavity.
That's when I talk about septal deviation.
And fourth paragraph is everything else.

Last but not least, fifth paragraph.
I think about those places the surgeon can get into trouble.
My goal as a radiologist is to take care of patients,
but number two, it's to help keep my surgeon outta trouble.
And that's when I mentioned these osseous defects.

Thank you so much for your attention.