0:00

Next case is a 40-year-old female who, um, got CT

0:05

imaging done for an altruistic renal donation and had

0:07

an incidental mass seen on these images in the liver.

0:10

So we can see there's a non-contrast phase and a

0:12

corticomedullary phase, a nephrographic phase, and we see

0:15

this arterially enhancing mass centered in the caudate lobe.

0:20

Very difficult to see on the non-

0:21

contrast phase and the equilibrium phase.

0:24

This is an indeterminate mass and an MRI

0:26

was, uh, ordered for further evaluation.

0:30

We'll start off T2-weighted sequences, and on both of

0:35

them, we can see the lesion here in the caudate lobe.

0:38

On the T2-weighted image performed without

0:39

fat saturation, the lesion is here.

0:42

It's quite difficult to actually see on this sequence, and

0:45

if you were scrolling through it very quickly up and down,

0:48

you may actually even miss it, despite the size of this.

0:50

This is probably at least three centimeters in size.

0:53

And it looks slightly hyperintense.

0:57

With respect to the liver parenchyma, some may argue that

1:00

it's very isotense with respect to the liver parenchyma.

1:03

And on the T2-weighted Turbospin echo sequence

1:05

performed with Fatsat, this is the sequence

1:08

that we're going to look at to really bring

1:09

out the true T2 signal within any liver lesion.

1:12

We can see that lesion here on the caudate lobe.

1:14

Again, quite tough to detect, slightly T2 hyperintense.

1:21

The next set of images we need to look

1:23

at are the T1 in and out of phase images.

1:25

And on both the out of phase image and the in phase image,

1:28

the lesion is very, very difficult to accurately delineate.

1:32

We know that it's sort of centered in the caudate lobe,

1:34

and it's probably going to be this lesion over here.

1:36

Um, it looks pretty much identical on

1:38

both the in and out of phase image.

1:40

It's probably slightly T1 hypointense, some may argue

1:44

that in fact it's isointense with respect to the liver

1:46

parenchyma, and that finding is pretty consistent on

1:49

the out of phase image and the in phase image over here.

1:52

Uh, there's no fat within it on the out of phase image,

1:55

that would manifest as a region of decreased signal on

1:57

the out of phase imaging, we don't see that over here.

2:01

the T1 FATSAT pre-contrast images, again we're

2:04

going to focus here on the caudate lobe region.

2:07

So here we have the T1 pre-contrast FAT SAT image,

2:13

and it's very, very tough to see where this lesion is.

2:16

We know that it's in the caudate lobe.

2:18

It's probably going to be somewhere in this location.

2:21

In this case, I'd probably say it's isointense

2:23

to the liver parenchyma because it's just so

2:25

difficult to really visualize where it is.

2:27

Now we have to look and see what it does

2:30

on the post-contrast imaging sequences.

2:33

So here we have our post-contrast sequences.

2:36

You can see the lesion again in the caudate lobe.

2:39

On the arterial phase images, we notice that

2:41

there is very brisk arterial hyperenhancement,

2:47

very homogeneous as well in its appearance.

2:49

On the portal venous phase and the equilibrium

2:52

phase that I'm not showing you over here, very,

2:54

very difficult to see where this lesion is.

2:56

Probably isointense on these images

2:58

with respect to the liver parenchyma.

3:00

Now in this instance, we gave EOVIS, the

3:02

agent with partial hepatobiliary excretion.

3:05

So let's have a look and see what

3:06

it does on that imaging sequence.

3:09

So, here's the axial post-contrast image obtained

3:12

20 minutes after giving intravenous Eovist.

3:16

We can see the lesion nicely in the caudate lobe, and it

3:19

is hyperintense with respect to the liver parenchyma.

3:24

So, these combination of findings of the nearly iso-

3:27

intense signal seen on many of the sequences, except

3:31

the arterial phase where it briskly enhances, and the

3:34

Eovist 20 minute phase where it's also hyperintense,

3:37

are quite characteristics of this

3:39

entity of focal nodular hyperplasia.

3:44

And the reason it's thought to be hyperintense

3:46

on the impatibility phase images is because

3:50

some of these lesions express a certain type

3:52

of receptor that allows this contrast to

3:56

enter the lesion but does not allow it to leave.

3:59

So depending on the concentration of these receptors,

4:03

you're going to see various degrees of hyperintensity.

4:05

Now, notice that this lesion, unlike our prior example

4:10

of focal nodular hyperplasia, did not demonstrate a scar.

4:14

And that's okay, because scars are only really seen in about

4:17

50 percent of cases with focal nodular hyperplasia.

4:21

So, while having a scar is quite characteristic of focal

4:24

nodular hyperplasia, it's not always present and doesn't

4:28

always need to be seen to diagnose a liver lesion as such.