0:00

So this next patient is a 40-year-old female with a history

0:04

of a gastrointestinal stromal tumor involved in the stomach,

0:07

and a staging CT scan was performed for further evaluation.

0:14

So as we scroll through her CT imaging, we'll note that

0:18

there is a rather large mass within the left hepatic lobe.

0:21

We can see it over here.

0:22

The patient is status post cholecystectomy,

0:27

and we can scroll up and down through

0:29

this indeterminate imaging features.

0:32

So, an MRI was, uh, requested to further evaluate this.

0:37

So, we'll start our evaluation of, uh, this

0:40

patient's MRI looking at the T2-weighted sequence.

0:43

And on the T2-weighted sequence performed

0:46

without fat saturation, we can see a rather

0:49

large mass within the left hepatic lobe.

0:52

And if we were to look at its internal T2 contents

0:55

within it, it looks different from some of the other

0:57

stuff we've seen so far in that it's not particularly

1:00

bright, certainly not as bright as the CSF over here.

1:04

And if anything, it sort of looks similar

1:07

to the adjacent liver parenchyma over here.

1:10

So, I would say this is iso intense or

1:15

minimally hyperintense with respect to the

1:18

liver parenchyma on the T2-weighted images.

1:23

Internally, we note that there are clefts

1:26

within it over here and over here and over here.

1:29

Perhaps some in this location that

1:31

are slightly more T2 hyperintense.

1:34

We'll get back to what those represent in a little bit.

1:37

On the T2-weighted sequence performed with fat saturation,

1:41

we can again, uh, look at the signal within this lesion.

1:44

Again, we use these turbospineco fat sat sequences

1:47

to really determine the T2 content of these lesions.

1:49

And again, looks quite similar to the adjacent liver

1:52

parenchyma, maybe iso to slightly hyperintense on the

1:56

T2-weighted images with respect to the liver parenchyma.

1:59

And it certainly has these clefts within

2:01

it that are much more T2 hyperintense.

2:06

The next set of sequences to look at are

2:08

the T1 in and out of phase, and this is what

2:10

the lesion looks like on those sequences.

2:17

hypointense with respect to liver parenchyma, right?

2:20

So it looks somewhat similar, but not quite the same.

2:23

And similar in the in-phase image, it looks iso to

2:26

slightly hypointense with respect to the liver parenchyma.

2:30

There are no areas of diminished signal on the out

2:32

of phase images to suggest fat within this lesion.

2:35

And there's no increased susceptibility

2:37

artifact on the in-phase images.

2:39

At the periphery of this lesion, there is some

2:40

increased susceptibility artifact over here and

2:42

that just comes from cholecystectomy clips in

2:45

this patient who had a prior gallbladder surgery.

2:48

We'll then proceed to our T1 FATSAT precontrast image.

2:51

And on this image, we can also see that the

2:54

lesion overall has signal intensity that is

2:58

somewhat similar to the liver parenchyma.

3:00

But, if you look at it very critically, we can

3:02

see that it's probably, if anything, a little

3:04

bit T1 hypointense with respect to normal liver

3:07

parenchyma and normal liver parenchyma over here.

3:10

What does it do when we give intravenous contrast?

3:12

So we move on to our post-contrast imaging sequences.

3:15

We have the arterial, portal venous, and equilibrium phase

3:17

images done over here, and I'll just settle in on a

3:21

representative portion of this lesion right over here.

3:24

In the arterial phase image, we note that the lesion

3:27

itself has pretty homogeneous arterial hyperenhancement.

3:35

On the portal venous phase image, the lesion

3:38

is somewhat iso intense to slightly hyper

3:43

intense with respect to the liver parenchyma.

3:45

So if we were to look at it, you can argue that

3:47

some portions look very similar to the liver

3:49

parenchyma or iso intense, and some portions remain

3:52

slightly brighter than the liver parenchyma.

3:55

And finally, on the equilibrium phase images, I

3:57

would argue that it looks very, very similar to the

4:00

liver parenchyma, almost completely iso intense.

4:04

Now, there are certain clefts within this lesion,

4:06

right over there, that do not enhance on the arterial

4:10

phase, and these, remember, were T2 hyperintense.

4:15

They don't enhance on the arterial phase, but as you go

4:18

from the arterial to the portal venous to the equilibrium

4:21

phase images, we can see that that same area now enhances.

4:27

And so we have a lesion that, for all

4:31

practical purposes, looks very similar to the

4:34

liver parenchyma on many of the sequences.

4:36

Except for the arterial phase where it's definitively

4:40

arterial hyperenhancing, and it has a little cleft of

4:43

T2 signal that fills in on our equilibrium phase images.

4:47

So if this is all we had, we would suggest that

4:50

this most likely reflects focal nodular hyperplasia.

4:55

Now when we evaluate patient focal nodular

4:56

hyperplasia, or if that's the clinical question,

4:59

we often do one final phase after giving an

5:02

agent which has partial hepatobiliary excretion.

5:06

We brought this patient back and did that final phase.

5:09

I'll show you what the lesion looks like on those images.

5:12

And so here are the final set of, uh, post

5:14

contrast images performed at 20 minutes after

5:17

giving, uh, intravenous, uh, contrast agent called

5:20

Eovist that has partial hepatobiliary excretion.

5:24

So this is with Eovist and we do these,

5:26

as I said, at 20 minutes post-contrast.

5:30

See the lesion here and it is relatively hyperintense.

5:36

Some portions may be iso intense but predominantly

5:39

hyperintense with respect to the liver parenchyma.

5:45

And so the combination of these findings on the

5:46

T2-weighted images, the post-contrast imaging, the

5:49

EOVIS findings, makes this lesion characteristic of

5:53

focal, nodular hyperplasia, now this is the second

5:58

most common benign liver tumor after hemangioma.

6:01

It occurs much more commonly in females than males,

6:06

and it occurs in females typically of childbearing age.

6:10

It's often incidental, seen in up to 90 percent

6:13

of cases, it's just an incidental finding.

6:15

And the thought previously with FNHs is that they were not

6:18

responsive to estrogen at all, but the current thinking is

6:22

that there may be some response to estrogen, such that if

6:25

patients are, uh, going to become pregnant or are pregnant

6:30

or an oral contraceptive pills, there is the risk of a

6:33

small amount of growth associated with these lesions.

6:40

associated with these despite, um, that potential

6:43

for growth, um, with high estrogen states.

6:47

On pathology, this manifests as a, uh, mass with a

6:52

central scar with radiating septations coming from it.

6:55

So it often looks like a central scar.

6:56

Radiating septations, um, and that central scar

7:00

is that portion that was T2 hyperintense and

7:04

that enhanced late on the equilibrium phase.

7:07

And so oftentimes when I look at a lesion and it sort

7:10

of looks like an orange to me, you cut open an orange

7:14

and cross section, if it looks like that, I'm going to

7:16

think that this could reflect focal nodular hyperplasia.