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The following is a 65-year-old

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gentleman with cirrhosis who's being

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screened for hepatocellular carcinoma.

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A few liver lesions, but we're going

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to focus on this one over here.

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So here we have a T2-weighted

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image with fat saturation.

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And this is a T1-weighted image with

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fat saturation without contrast.

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And this is the lesion in question,

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better seen on this sequence over here.

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On the T1-weighted images, it's relatively hyper-

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intense when compared to the liver parenchyma.

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On the T2 images, it's very difficult

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to see. It's probably iso-intense

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with respect to the liver parenchyma.

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And so something like this, you know,

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could be considered one of these

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cirrhotic nodules given its appearance,

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possibly this is a dysplastic nodule.

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The next thing to look for in any of

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these nodules is to see if there's

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any internal enhancement within it.

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So here we have a T1-weighted sequence

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with fat saturation, with contrast.

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This is in the arterial phase.

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This one over here is in the portal

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venous phase, a little bit later.

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What I'm actually showing you here are

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subtracted images, and the reason we use

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subtracted images is because this lesion

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has hyperintense T1 content to begin with.

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So you want to make sure you remove that

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prior to looking at the post-contrast

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images, hence the use of subtracted images.

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We can find the lesion again, right

1:18

over here and right over here.

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In the medial left hepatic lobe, and it

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doesn't demonstrate any internal enhancement.

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So, we have a lesion, it's T1 hyperintense,

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T2 isointense, no enhancement.

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It would not be unreasonable to

1:32

describe this as a dysplastic nodule.

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Now, as it has been mentioned, these

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dysplastic nodules can undergo various degrees

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of differentiation from low grade to high

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grade, and once you start getting to the

1:42

high grade, many people consider them

1:45

as precursor lesions to developing frank

1:47

malignancy, which is hepatocellular carcinoma.

1:50

And the key then when evaluating serial

1:53

studies and looking at these nodules is

1:55

to really see, does the imaging appearance

1:57

change on subsequent studies as the T2

2:00

appearance changes, the T1 appearance changes?

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Is there any enhancement associated with this?

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So if we fast-forward imaging studies on this

2:08

patient to about a year after that initial

2:10

imaging study, we can relook at this nodule

2:13

in the medial left hepatic lobe.

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And on the T2-weighted image

2:16

with fat saturation, we can see

2:18

that its appearance has changed.

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Previously, it was isointense with

2:22

respect to the liver parenchyma, but

2:24

now, certainly internally, if you look at

2:25

this portion of it, it is hyperintense.

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If we look at this nodule on the T1-

2:31

weighted sequence with fat saturation,

2:33

before giving contrast, again, the

2:36

nodule's appearance has changed.

2:37

It probably has gotten a little bit

2:39

bigger. But internally, it is hypointense

2:42

with respect to the liver parenchyma,

2:44

whereas previously it was hyperintense or

2:46

brighter than the liver parenchyma itself.

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Finally, we can look at this nodule on

2:50

the T1-weighted fat-saturated image.

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Post-contrast, this one

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is in the arterial phase.

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And internally, not a lot of

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enhancement at this cut over here.

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But if we scroll up and down through this

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lesion, what we find is that there are

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foci of internal enhancement that are new.

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As can be seen along the cephalodermal aspect of

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this lesion, this little nodule of enhancement.

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And so this is sometimes referred to

3:15

as a nodule-within-a-nodule appearance.

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This enhancing nodule within

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a pre-existing liver nodule.

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There's no washout associated

3:25

with this in this particular case.

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So it's an enhancing nodule within

3:30

an otherwise non-enhancing lesion.

3:32

And this is thought to reflect a more high-

3:35

grade or de-differentiated dysplastic nodule

3:38

that may subsequently become

3:40

a hepatocellular carcinoma.