0:01

So this patient is a 74-year-old gentleman

0:04

who is post-liver transplant and has elevation

0:09

in liver function tests, and an MRI was

0:11

requested in order to evaluate these findings.

0:14

Start off with T2-weighted images,

0:17

which were performed with fat saturation.

0:21

I'll stop on this slice over here

0:22

and we can notice in the right

0:23

hepatic ducts, the ducts are dilated.

0:26

We can see over here, they are

0:28

larger than what we would expect, not

0:30

tremendously dilated, but nevertheless

0:32

more than what we would expect to be normal.

0:36

Let's keep on scrolling, and as you go

0:37

more downwards, you can see, you know,

0:39

larger ducts that are more dilated.

0:42

And again, right-sided ductal dilatation.

0:45

The remainder of the liver looks okay.

0:47

It's really just the right hepatic lobe,

0:49

and specifically almost the posterior

0:51

aspect of it that's more dilated.

0:53

Some ducts that start to join

0:54

in over here look dilated.

0:57

Some of the ducts here may be now dilated.

0:59

And now we're starting to get to a potential

1:02

filling defect inside of one of these

1:03

ducts, this T2 hypointense structure.

1:06

We're going to get to that in a bit.

1:08

You can follow it over here as well.

1:10

And as we go to the extrahepatic biliary tree,

1:13

relatively normal caliber over here, all the

1:16

way down to the ampulla and the duodenum.

1:20

All right.

1:20

So let's look at those findings one more time.

1:23

Right-sided ducts that are dilated.

1:26

Some filling defects inside the biliary

1:28

tree as you go towards the porta hepatis

1:30

and then beyond the porta hepatis, really

1:33

beyond that anastomosis, which the bile

1:35

ducts are the biliary anastomosis, the

1:37

biliary tree is relatively normal in caliber.

1:40

Let's have a look at the T1-weighted images.

1:42

This is a T1 fat-saturated

1:45

image in the axial plane.

1:46

We're going to relook at those findings

1:49

and specifically those filling defects.

1:51

So you can see some of the

1:52

bile ducts that are dilated.

1:53

They're hypointense.

1:55

As you go downwards, notice that those

1:56

filling defects are T1 hyperintense.

1:59

We can see them sort of conform

2:01

to the biliary tree itself.

2:03

It just sort of fills

2:04

whatever space is there.

2:05

And I'm going to sort of show

2:08

this in a different plane.

2:10

So in the reconstructed coronal plane,

2:13

we can see that that region, which is

2:17

T1 hyperintense, actually conforms to

2:20

a very linear sort of filling defect

2:23

that's within the bile ducts themselves.

2:26

It almost looks, it's almost geographic in

2:28

shape and very, very linear and almost tapered

2:31

borders, uh, superiorly and inferiorly.

2:34

So remember this patient is a

2:36

patient who is post-transplant.

2:38

Uh, the bile ducts are dilated in

2:40

the intrahepatic ducts as it goes

2:41

towards the extrahepatic biliary tree.

2:44

There's a relative area where transitioning

2:46

between dilated ducts and normal ducts.

2:48

So probably there's a region of stricturing,

2:51

particularly given the history of elevated LFTs.

2:54

But what's also interesting to note is

2:56

that there are some filling defects sort

2:58

of in the intrahepatic ducts upstream

3:00

from the region of the anastomosis.

3:02

And again, that tells us that there's some

3:03

stasis, but these filling defects have a

3:06

relatively unique appearance in that area.

3:09

You know, they are T2 hypointense,

3:11

T1 hyperintense, but they're not

3:12

nice and round or like a triangle like

3:15

we see a lot of choledocholithiasis.

3:17

Rather, their shape is much more linear,

3:19

and they're contiguous, and they almost

3:21

look like they're conforming to the shape

3:24

of the bile ducts in which they're forming.

3:27

If we look at the ERCP images, we

3:29

can see the scope over here; we'll

3:31

cannulate the common bile duct.

3:33

And you can start to see that filling defect

3:35

is a very linear filling defect that almost

3:37

conforms to the shape of the bile ducts.

3:40

And so the reason I wanted to show this

3:41

case is that we've talked about different

3:44

types of filling defects in the biliary

3:46

tree, such as choledocholithiasis or stone.

3:49

We've talked about biliary

3:51

sludge that can occur as well.

3:53

And we've talked about different types

3:54

of stones, pigmented, which are T1 hyper

3:57

intense, non-pigmented stones as well.

3:59

This is an additional type of filling

4:01

defect that is often seen in

4:02

patients with biliary transplants.

4:04

And we call these biliary casts.

4:08

And what happens is that you have a solid

4:11

cast of bilirubin that forms inside the

4:14

biliary tree that can result in obstruction.

4:18

And to differentiate it from biliary

4:21

sludge, biliary casts are much more

4:24

T2 hypointense or T1 hyperintense.

4:28

And just looking at them, you know,

4:29

sludge is just sort of thickened

4:31

bile; it doesn't quite precipitate.

4:32

Well, this is actually a solid

4:35

precipitated form of bilirubin.

4:37

When you take it out, it's sort of the

4:38

solid thing that you're sort of taking

4:40

out of the biliary tree itself.

4:43

The key though here is that you often see these

4:45

in transplanted patients, and when you see them,

4:48

they're almost linear, curvilinear in shape.

4:50

They can be T1 hyperintense and they conform to

4:54

the shape of the bile duct, which makes it quite

4:55

different from any of the other filling defects

4:58

we've talked about in this master course.