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All right, so for our last case today, we're going

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to try to put together an approach and a report for a

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more complex disease in a patient with Crohn's here.

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And so again, as always, the first step is to

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look at our key sequences for detecting disease.

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So I'm going to start with this

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coronal post-contrast series.

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And right away in the pelvis, we see several

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loops of bowel that are clearly enhancing

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more than the adjacent similar loops.

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These end up being ileal loops.

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Of course, you can see it connecting

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here with the cecum in the right abdomen.

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So there's a lot of inflammation

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involving these ileal loops.

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That's clearly evident with this enhancement

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pattern, where you see that inner wall enhancement

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and some suggestion of wall thickening.

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We're also going to try to see if there are any skip

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lesions or other lesions in the more proximal bowel.

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And to me, this proximal bowel looks

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to be enhancing similarly throughout.

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Also, the colon doesn't look like it has a

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lot of abnormal enhancement in this region.

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You see some stool in the colon, but you

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don't see a lot of hyperenhancement.

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So, so far, it's really the ileal disease

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that's most prominent, with potentially a little

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bit of enhancement of the ascending colon,

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which may indicate some mild disease there,

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and the remaining bowel looks pretty normal.

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So, looking at our T2 sequence, we again

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see a similar appearance of the distal ileum

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here with some clear wall thickening.

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You can see some haziness in the

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fat, which is an important finding.

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It indicates a more severe disease process here.

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As far as the remaining bowel, it looks

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like fairly normal fold-type patterns

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here in the jejunum and the colon,

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it doesn't show any severe wall

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thickening that we can see.

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Looking in the axial plane to help us identify

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more diseased segments, we again see that

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the more proximal bowel looks pretty normal.

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The colon, again, is filled with

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stool, but otherwise appears normal,

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with the exception of, I think, a little bit

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of mild inflammation of that ascending colon.

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So very mild enhancement without other findings.

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And lastly, looking at diffusion, our other

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key detection sequence, I believe we see a

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lot of diffusion abnormality in the pelvis.

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And in the remaining bowel, we don't see

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a lot of diffusion signal abnormality.

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We do see some scattered lymph nodes,

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which don't look especially enlarged,

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but maybe some reactive lymph nodes.

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And then that ascending colon doesn't look

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like it has a lot of inflammation here.

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So if there's any disease in

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the ascending colon, it's really quite mild.

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So our primary focus is going to be

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this diseased bowel in the pelvis.

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For our next step, we want to

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characterize that a little more fully.

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In this case, where there's so much disease, getting

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precise measurements of the length of disease

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involvement isn't going to be feasible, particularly.

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So just giving a ballpark estimate, saying

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there's maybe 30 to 40 centimeters of disease

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involvement, is generally how I approach this.

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Okay.

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Next, we want to see if it's acute or

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chronic, and there's clearly a large

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component of acute inflammation here.

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In addition to the, you know, marked hyperemia

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early, it does look like there's edema in

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the wall, causing that wall thickening.

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When we look at our fat-saturated sequence, it does

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look like those loops of bowel are brighter

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than similar appearing loops of bowel elsewhere

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and brighter than the adjacent skeletal muscle.

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So there's a large acute

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component to this disease process.

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Additionally, we've got this enhancement

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that goes outside of the wall.

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And so that, first of all, indicates there's

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a pretty significant acute component with this

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enhancement and abnormal T2 signal that we're

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seeing outside the wall of the bowel in that region.

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And it also indicates that we need to look really

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closely for any strictures or fistulizing disease.

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When we look at this sequence, it does look

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like we have that kind of asterisk look.

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So it does look like

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we're going to have a complex

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fistulizing disease here.

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And this is connecting all these loops of

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diseased small bowel in the lower abdomen there.

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So I would characterize this as a complex fistula

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with multiple tracts, connecting loops of small bowel.

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That can be confirmed on not just that sequence, but on

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other projections showing that similar asterisk shape.

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And of course, when there's a fistula,

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we need to look for abscess.

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So we do see some free fluid down here,

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but this doesn't have a wall around it.

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So it looks like it's just simple

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layering free fluid on this T2 sequence.

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We're not going to pick up

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that fluid very well here, but...

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What we can see on our post-contrast

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sequence is any pockets of enhancement

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that aren't directly connected to bowel.

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And here we see that there's

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maybe a little pocket here.

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You can see these loops of bowel and these tracts

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connecting these loops of bowel all throughout here.

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But this does not have an associated loop of bowel.

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It's an isolated pocket in the mesentery

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of the small bowel in that region.

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So that's concerning that

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there may be an abscess there.

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So how do we confirm that?

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Well, let's look at our other sequences.

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And when we look at this diffusion sequence,

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we see right where that area is, where

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there's that pocket, is very restricting.

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And that often happens when you have a lot of pus

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or a lot of infected cells that are tight together.

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They show some diffusion restriction.

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So this is confirmatory evidence that there's a very

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small abscess associated with this complex fistula.

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When we look at our other sequences that

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further confirm that we kind of have

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this hazy T2 look at the site where that

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suspected abscess is outside the bowel wall.

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We're going to characterize that as an abscess.

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We're going to want to give a

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size measurement for that abscess.

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It's not huge, it's only one and a

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half centimeters, but it is real.

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And so we want to include that in our report.

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So in the end, our final impression is going

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to include the diseased segment, which is

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predominantly the distal ileum with possible

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mild involvement of the ascending colon.

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It's going to say that there's 30 to 40

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centimeters of distal ileal involvement.

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There's associated fistulization

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and active inflammation

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of the loops of bowel.

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And there's a small one and a half centimeter abscess.

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So those are going to be the key components

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that we want to put in our impression.

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Hopefully, that helps you as far as how to take an

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approach that's reasonable to these more complex

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cases that can take a lot of time and energy

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to really figure out exactly what's going on.