0:00

For our next case, I'm gonna show you something much more

0:02

subtle than the, uh, the outright colon cancers

0:05

that you're seeing, uh, before.

0:07

So in this case, we've got something along the wall

0:11

of the cecum here, and this is an untagged case.

0:15

So you can see how much more difficult it is to read, uh,

0:18

a case that doesn't have oral contrast on board,

0:21

or where the oral contrast may not have reached this portion

0:24

of the colon yet, or may have passed beyond the, the,

0:26

this portion of the colon.

0:27

You're not gonna see anything submerged here,

0:30

but we do see a little bit

0:31

of mural irregularity here on the three D view, something

0:35

that does not look like an adjacent to nostril fold.

0:37

Here's our ileocecal valve for comparison.

0:40

Again, looking very, very much like a pair of lips here

0:45

telling you that this portion is the cecum.

0:47

And right along this wall there's a little bit

0:50

of mural irregularity.

0:51

It looks very flat if you look at it in profile, it's,

0:54

it's almost like a little bit of a carpet patch.

0:57

This is what we term a flat lesion.

0:59

You want to confirm that it's soft tissue and attenuation

1:02

and doesn't represent just adherent, um, stool.

1:06

And in this case, without fluid tagging material,

1:08

it can be more challenging to make that di distinction.

1:11

But I do see a little bit of, um, soft tissue plateau, uh,

1:16

of thickening here in that portion of the cecum.

1:18

And you want to confirm that it's in

1:21

that same position on the prone positions here, just

1:23

to confirm that it's not a piece of, um, stool

1:27

that might be, um, redistributing on

1:30

changes in patient position.

1:31

And in that same location here, we have something

1:33

that looks very much similar to

1:35

what we're seeing on the supine images,

1:38

and it's measuring more than one centimeter in size.

1:41

So this is a, a subtle finding which, um, uh,

1:45

has been termed a flat lesion

1:47

and many endoscopists had previously, um,

1:51

criticize CT colonography for not being able

1:54

to pick these findings up.

1:55

But I think now that we've seen more of these findings, uh,

1:59

we're better at be able

2:01

to appreciate their appearance on CTC.

2:04

And when oral contrast is used for, for tagging,

2:08

these lesions do tend to have a predilection for,

2:12

uh, contrast coating.

2:14

So you may get a little thin coating of contrast stuck to

2:17

that carpet lesion, uh,

2:20

and not sticking to the rest of the colonic mucosa.

2:22

So in that case, they can actually act to tag a flat lesion

2:26

and help you identify it as long as you realize that

2:29

underneath that contrast coat, there's a little plateau

2:32

of soft tissue thickening, undermining it, telling you

2:35

that you're dealing with a flat lesion.

2:37

So this is a flat lesion in the cecum.

2:40

There were other findings in this, uh, particular patient,

2:45

something in the descending colon as well.

2:47

There are other polyps,

2:48

more salur polyps in this particular case.

2:52

But, uh, even that SQL fat lesion alone would've been enough

2:55

to, to send somebody on to, uh, endoscopy

2:59

For confirmation.

3:00

And in this case, it was confirmed.

3:02

The last teaching point I'm gonna make here is sometimes

3:05

things that, that are outside

3:06

of the colonic lumen can push in on the lumen

3:08

and look like something

3:10

that could be potentially submucosal.

3:12

Most commonly you're gonna see that with adjacent, uh,

3:15

small bowel loops, for example, that might be

3:17

pressing in on the colon or the, um,

3:19

the spleen at the splenic flexor

3:22

or the liver edge at the hepatic flexor.

3:24

Sometimes those can push into the wall.

3:26

Those are usually pretty easily recognized on CTC

3:29

because you can see the adjacent structure outside

3:32

of the clo lumen, but it can oftentimes, uh, be a little,

3:36

um, of a dilemma for the endoscopist

3:39

because they can't see what's on

3:40

the other side of that wall.

3:42

So, uh, in that sense, our x-ray vision helps us see

3:45

beyond the wall and beyond the lumen of the colon.

3:47

In this case, we've got something

3:49

that looks like it's pushing on this,

3:50

this fold in the rectum here,

3:52

but this one's pretty easily differentiated

3:54

because you can see the, the tip

3:56

of the balloon is pushing on that, uh,

3:59

wall from the other side

4:00

and giving you that false impression on this side.

4:03

And it's easily appreciated on our, um, NPR views as well.