0:01

So this patient is a 55-year-old male, history of

0:05

pre transplant evaluation, trying to do a liver transplant.

0:09

So they wanted to look at the liver to make sure

0:11

that there are no abnormalities prior to doing so.

0:14

We'll start off by looking at the T2, non-fat saturated

0:18

image, as I do with most of the exams of the abdomen.

0:20

And again, we're focused on the gallbladder,

0:22

so there's a lot of stuff going on here,

0:24

but let's just focus, uh, immediately on the gallbladder.

0:27

We can see that there is, um, a somewhat

0:30

familiar appearance by now of a gallstone.

0:32

It's T2 hypointense, somewhat

0:35

lobulated borders in this instance.

0:37

And it's lying within, uh,

0:40

an otherwise normal-appearing, uh, reasonably

0:42

normal-appearing gallbladder over here.

0:44

And we'll look at it on T2 fat-saturated image,

0:46

19 00:00:49,255 --> 00:00:50,725 you can see again that it has

0:50

that T2 hypointense appearance.

0:53

Some of the borders in this instance look a little

0:55

bit more sharp than they do on the first image.

0:58

I wanted to show it to you on the

0:59

T1 pre-contrast fat-saturated image

1:06

because it has a sort of

1:07

different appearance over here.

1:09

So this really does look like a gallstone.

1:11

However, the gallstones that we've been

1:13

accustomed to seeing so far were both

1:16

T2 hypointense and T1 hypointense.

1:19

However, this one is T1 hyperintense.

1:23

It's bright on these images.

1:24

And so it has sort of a different

1:26

imaging appearance that we can see.

1:29

When we give contrast, let's see what it looks like.

1:33

This is a T1-weighted, fat-saturated, post-contrast

1:37

image in the portal venous phase I'm showing you.

1:41

And it looks like it does enhance; however, because

1:44

it contains T1 hyperintense content, you're not

1:47

sure if this brightness on the post-contrast

1:50

images is present because it truely is

1:53

enhancing or whether this just reflects

1:56

the T1 hyper intense content

1:58

that it contained to begin with.

2:00

And so for that, we need to look at subtraction images.

2:03

When we look at subtraction images,

2:05

there's a little bit of misregistration.

2:06

You can see how the liver here,

2:08

uh, is a little bit misregistered.

2:09

There's this artifact associated with it, but when

2:11

you look at this area in general, there's really

2:13

no enhancement associated with this finding. So this

2:16

is a non enhancing lesion within the gallbladder.

2:21

And so, this imaging appearance is characteristics

2:23

of the less common type of gallstone, which is the

2:27

pigmented gallstones. And as we said gallstones

2:30

can be either be qualified as cholesterol

2:34

gallstones or pigmented gallstones in the U.S.

2:36

60 00:02:37,260 --> 00:02:39,690 The vast majority of our cholesterol

2:39

gallstones, which appear T2 and T1 hypointense.

2:44

And then you have that subset of pigmented gallstones,

2:46

which do appear T2 hypointense as seen over here.

2:50

However, on the T1 weighted images,

2:52

they have hyperintense content and they

2:55

won't enhance when you give contrast.

2:57

And so we generally qualify something as a pigmented

3:00

gallstones if its internal content contains less

3:03

than 50% cholesterol and it tends to have

3:06

a higher percentage content of other constituents

3:09

such as calcium bilirubinate, other glycoproteins.

3:12

And one of the reasons that this is important

3:16

is that it's thought that these are easier

3:18

to remove via endoscopic lithotripsy,

3:21

pigmented gallstones rather

3:23

than the cholesterol gallstones.

3:25

But I think for practical purposes, it's just

3:28

important to know what gallstones could look like.

3:31

The sort of variable appearance that when

3:33

you look at images, you're not astounded or

3:35

surprised by the appearance of gallstones.

3:38

If they appear T1 hyperintense,

3:40

they can certainly appear like that.

3:41

And when they do, they're almost certainly

3:44

going to be pigmented gallstones.