0:00

Okay, this was an SMA embolism

0:03

causing mesenteric ischemia.

0:05

Here on this 3D image, you can see the celiac axis,

0:07

and the lack of enhancement of that proximal SMA,

0:09

as we saw on the images previously. Acute arterial

0:13

occlusion is usually from an embolic source, most

0:15

commonly from a cardiac source with a patient

0:18

who may have AFib or other cardiac abnormalities.

0:21

So, we always look for intracardiac thrombus

0:24

in the setting of emboli or embolic disease.

0:26

I would say also, even when I'm trying to protocol

0:29

these abdominal pains, sometimes if someone tells

0:31

me that the patient has underlying AFib or a

0:34

cardiac issue such as this, I will automatically

0:37

protocol that case with an arterial and portal

0:40

venous phase because these emboli are so much more

0:43

easily visualized in the arterial phase of imaging.

0:47

You can also get in situ thrombus.

0:48

That's probably 15% to 30%—just develop

0:51

at the level of an ostium, secondary

0:53

to underlying atherosclerotic disease.

0:55

Um, you can see that this patient

0:56

has a lot of calcifications.

0:58

They had actually already had surgical aortic

1:00

graft, so they're definitely a vasculopath,

1:02

so that is an opportunity as well.

1:04

The fact that there were splenic infarcts

1:06

there probably cinches the deal that

1:07

it was more likely embolic in nature.

1:09

Aortic dissections can occur and result in mesenteric

1:13

ischemia as well, so you always want to look for

1:16

that as a cause for your mesenteric ischemia.

1:19

So, how does the bowel look with mesenteric ischemia?

1:22

Because the bowel, you know, has lack of blood

1:24

flow and the blood supply is reduced, it'll become

1:26

ischemic, and it will have typical features of

1:29

ischemic bowel, including this absent enhancement.

1:32

You can see as the enhancement more

1:34

proximally of these little folds just

1:36

gets lost in these dilated ischemic folds.

1:39

You're going to have a very thin

1:40

wall in arterial enhancement.

1:41

It's a blood

1:42

inlet problem.

1:44

You're not getting enough blood to the bowel,

1:45

so the wall will be nice and paper thin.

1:47

You can see that along where these dots of air are.

1:50

Usually you'll have some ileus.

1:51

The bowel isn't going to like to be

1:52

ischemic, it's not going to do its work

1:53

if it doesn't have the blood it wants.

1:55

I mean, it's not going to be happy.

1:57

So, as a result, you'll get some dilatation as well.

1:59

You may go on to pneumatosis, where there's actually

2:02

air in the bowel wall.

2:04

As that mucosa breaks down from ischemia, it

2:06

allows air from the intraluminal contents to

2:09

go into the wall, which can then be reabsorbed

2:11

into your portal venous tract as well.

2:14

So, this is a beautiful appearance of

2:17

arterial ischemia of the small bowel.

2:19

This would be considered a watershed zone for the SMA.

2:22

There are a lot of variable

2:24

watershed zones that aren't as

2:26

applicable to the general population because it

2:28

depends on where your atherosclerotic disease is.

2:31

But this would definitely be a location where

2:34

I've seen a number of ischemic insults from

2:36

SMA occlusions and/or the like, frequently

2:39

affects the distal small bowel and cecum.

2:42

Here's a case which is similar.

2:44

But this time we can see that there's a small focus

2:46

of enhancement within the lumen, and there's a nice

2:49

crescent of lower attenuation. On the sagittal image,

2:52

we can see just that nice small, um, lumen here.

2:56

This is an SMA dissection.

2:59

We do see celiac axis and SMA dissections at times.

3:03

They don't have a really good natural

3:05

history of who gets these or why.

3:07

Definitely higher on your Ehlers–Danlos

3:09

patients, but they can be somewhat sporadic and

3:13

definitely not something that

3:14

people would be expecting.

3:16

So, I always look very carefully at the vessels.

3:18

It's definitely one of my, uh, search patterns.

3:21

I like to look at the celiac axis and SMA specifically

3:24

on the sagittal view because I always feel like

3:25

this view gives me the best image of those vessels.