0:01

So when considering disease detection, we certainly

0:04

want to look at all the sequences at some point in

0:06

your exam, but really for the detection portion,

0:09

these are the four that I find the most valuable.

0:11

You've got the T2 sequence without fat

0:13

saturation, which gives you a good look

0:15

overview and a good look at the anatomy.

0:17

You have the post-contrast sequence.

0:20

And typically, I use one of the first two time

0:23

points, whichever shows up most clearly.

0:25

In this case, this is arterial phase, which is

0:28

going to show you the early enhancement really

0:30

well, and that can help you detect things.

0:33

You also want to look at the axial version

0:35

because seeing the ball in at least a second

0:38

projection can oftentimes help you identify

0:40

disease segments that you aren't going to pick

0:42

up in the coronal series alone, and then you

0:45

want to look at the diffusion-weighted images.

0:47

So I typically look at the high-B value diffusion

0:50

weighted images, which is the most sensitive

0:52

sequence at times when it turns out to be

0:54

high quality to detect areas of inflammation.

0:58

For these last few cases, I think we're going to

1:00

really try to pull it all together and talk about

1:02

how to globally approach exams where you're looking

1:06

at Crohn's disease and talk about those exams

1:09

and how to go about putting a report together.

1:13

And so, this is how I typically do it.

1:17

I'm not going to go dictate the whole thing,

1:19

obviously, but we'll talk about the highlights

1:21

about how we go about putting a report together.

1:23

So the first stage for the

1:25

small bowel piece is detection.

1:27

And obviously, we need to find all the segments

1:31

of Crohn's disease and characterize the disease.

1:34

So in this case, there's obviously an area of

1:36

thickening here that we're going to say is

1:39

Crohn's disease.

1:39

And so we've detected that.

1:42

But before we move on to characterization,

1:44

we want to go through and detect everything else.

1:46

Also, we're seeing that that looks to

1:48

be in the distal ileum, but the terminal

1:50

ileum doesn't look totally normal here.

1:52

It doesn't have complete pulsation.

1:54

It doesn't look too edematous, but it seems

1:56

like the wall pattern's a little bit atypical.

1:59

So let's look a little more closely at that.

2:01

And here again, I think we see that that area that

2:04

was thickened is enhancing. And the distal of that,

2:08

it looks relatively okay in terms of enhancement.

2:11

So there's not a lot of active disease

2:13

there, but there may be some chronic changes.

2:16

Looking at the rest of the bowel on this early arterial

2:20

phase exam, we see what we typically see, which is a

2:23

little more enhancement in the jejunum, but no jejunal

2:26

segments which are enhancing more than other segments.

2:29

And then we also want to look at the large bowel

2:31

and we look through that and see that there's no

2:34

areas of abnormal thickening or enhancement there.

2:37

Obviously, you want to use all your

2:39

sequences to help you with detection,

2:41

but I think that these four are the key ones.

2:43

And so, we've already done half of them.

2:45

And we also want to look at our axial images

2:49

post-contrast because sometimes that'll

2:51

help us pick up things that just are in

2:56

So again, we see that disease segment here, and

2:58

I think we can probably see a little more clearly

3:00

see that this bowel is not totally normal.

3:02

It looks like there's some chronic changes,

3:05

a little bit of irregular patchy enhancement.

3:08

And this sequence was a little more

3:10

delayed, which suggests that there have

3:12

been some chronic changes in that segment.

3:15

We also see that there's a lot more fat here.

3:17

So it's got some of that fibro-fatty proliferation

3:20

that we see with chronic Crohn's disease.

3:22

Looking through the sigmoid and colon,

3:24

we don't see any other disease segments or areas

3:26

that are enhancing more than others.

3:29

And then lastly, I think key for detection

3:32

86 00:03:33,150 --> 00:03:34,640 is to look at our diffusion sequence.

3:34

So I just look at the high-B value diffusion for

3:37

this, and we see that that disease segment does

3:40

have restricted diffusion, and it just jumps off the

3:44

page at us that that's an abnormal segment of bowel.

3:48

We see a little bit more signal down here,

3:50

and so we want to make sure we correlate that to our

3:52

other sequences, but I think that that's just

3:54

because there's a little more fluid in this bowel.

3:57

And then one of the pitfalls of

3:58

diffusion is that decompressed segments

4:00

will show up just a titch brighter.

4:02

So if they look decompressed, don't

4:04

give too much credence to that.

4:06

So I think that after going through all these

4:09

sequences, we can pretty well say that the

4:11

only segment we need to fully characterize

4:13

is that area of distal and terminal ileum.

4:16

So next we're going to talk about

4:18

that in terms of inflammation.

4:20

So in this case, it does look like there's

4:22

some active inflammation, right?

4:23

We saw that it had pretty

4:25

significant early enhancement.

4:26

It's got increased T2 signal

4:29

it appears on that sequence.

4:31

And we want to confirm that with some sort of 113 00:04:34,850 --> 00:04:37,639 fat-saturated sequence to make sure that

4:37

that's a true edema or edematous picture.

4:41

So on our fat-saturated sequence, sure enough,

4:44

we see that this is brighter than the adjacent fat.

4:46

It's brighter than the skeletal muscle.

4:48

So that's a true area of edema.

4:51

Next, I do think it's important that

4:53

we measure the area of inflammation.

4:55

So there's evidence showing that the

4:58

length of inflammation is important and

5:02

does correlate to the disease severity and

5:04

is another thing that can be monitored.

5:06

So I try to measure areas of active inflammation,

5:08

and this one's coming in at close to 5 centimeters.

5:11

So we're going to include that length and the

5:13

description of it as active in some of the

5:16

things that make me say it's active.

5:18

Next, we're going to evaluate for other

5:19

findings, so strictures and fistulas.

5:22

In this case, we don't see any fistula.

5:24

There's no bowel communicating with this

5:26

that looks to be, that looks like it tracks.

5:29

There's no penetrating disease.

5:31

There's no abscess in the region.

5:32

However, there does look to be some

5:34

persistent luminal narrowing associated

5:36

with some dilation just proximal to that.

5:39

So there is some degree of stricturing

5:41

here, at least moderate stricturing.

5:44

If you have dilation that's greater than

5:46

four centimeters in the upstream bowel,

5:48

you can call it moderate or severe.

5:49

So those are the key things that we're going to

5:51

include in our report as we put the dictation together.

5:54

In addition, obviously, we're going to look for

5:58

all the extraintestinal manifestations of Crohn's

6:00

disease, such as PSC, and look in the bones.

6:03

And then we're going to do our standard evaluation

6:06

of the remaining organs for any incidental findings.