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Warm greetings to all viewers.

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My name is Mahan Mathur, and I'm an associate

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professor of radiology and biomedical

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imaging at the Yale School of Medicine.

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This master course will cover the MR imaging

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appearance of malignant liver lesions, and

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this first section will serve as a brief

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introduction and roadmap of how we're going

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to be covering the content of this course.

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So the first thing I want to discuss is

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why we're sort of talking about this topic.

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Why is this topic actually important?

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Well, as it turns out, malignant

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liver lesions are very common.

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If we look at all malignant liver

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lesions, they account for about the six

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most common cause of cancer worldwide.

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And if we look at overall mortality, uh,

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by some estimates will account for the

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second leading cause of death from cancer.

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And a relatively unique aspect of some

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malignant liver lesions is that we can use

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imaging to make a diagnosis without the need

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for pathology.

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So if we're able to understand how to approach

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these lesions, we can make a definitive

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diagnosis, obviate the use of any needles to

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get a tissue sample, and proceed to treatment.

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Now, if we look at malignant liver lesions,

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we can categorize these as primary malignant

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lesions or secondary malignant lesions.

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It's important to know that secondary

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malignant lesions are by far more

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common than primary liver lesions.

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At an estimate for about

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20 to 40 times more common.

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So if you see a liver lesion,

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that's going to be malignant, most

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likely it's going to be secondary.

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When I say secondary, it really means

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that it's going to be a metastasis.

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If we look at primary liver lesions, the most

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common by far is hepatocellular carcinoma.

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So over the course of this lecture

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series, we're going to be focusing

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quite a bit on hepatocellular carcinoma.

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And of course, why are we using MRI for the

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purposes of looking at these liver lesions?

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Obviously, MRI is very useful; there's

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no ionizing radiation involved, which

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is always preferable if possible.

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But also, MRI is really proven to

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be the definitive, non-invasive

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way of imaging liver lesions.

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This primarily arises from its inherent

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improved soft tissue resolution.

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It can really differentiate subtle areas

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of soft tissue, small areas of increased

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enhancement; it can also differentiate those.

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And it really allows radiologists

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to make a more confident diagnosis.

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And some of that also arises from the fact that

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with MR imaging, when interpreted correctly, we

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can obtain, you know, certain types of sequences

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that can allow for a more confident diagnosis.

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So, how are we going to go about covering the

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content in this course, in terms of the outline?

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So, normally, I'd like to start off talking

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about MR sequences, but the reality is

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that the overall approach to imaging

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and evaluating malignant liver masses

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is quite similar to the approach that

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we would use for benign liver lesions.

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And we've already covered

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that in an earlier course.

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So if you already have it, I would suggest

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that you refer to that video vignette series

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before proceeding with this course to learn

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a little bit about the sequences that we use.

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The only two things that I'll mention at

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this juncture, in terms of sequences for

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malignant liver masses, is that with benign

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liver lesions, my approach is usually

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to look at the T2-weighted sequences

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followed by the T1 in and out of phase,

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followed by the T1 pre and post contrast.

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Whereas with malignant liver lesions,

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particularly when I'm evaluating for

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hepatocellular carcinoma, my post-contrast

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sequences are often the ones that I rely on

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and look at before I look at everything else.

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And we'll go through that as we

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go through the case series today.

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The second point I'll make is, I'll talk

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about with sequences is something that we've

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gotten feedback from the prior courses is

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you know, what is the utility of diffusion

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weighted imaging in evaluating liver masses?

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And to that, I'll say that at least in

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our experience, and this has been borne

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out in the literature to a certain degree,

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diffusion-weighted imaging is useful to

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differentiate purely cystic masses from

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solid masses, but it has very limited utility

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to differentiate among solid tumors.

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So I can say that in our own practice, we don't

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typically use diffusion-weighted imaging very

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commonly, and the only instance where we might

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consider using it is if, for some reason, the

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patient can't get intravenous contrast, so maybe

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diffusion-weighted imaging can give us some

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more information about the lesion in question.

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But even understanding that in those cases,

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diffusion-weighted imaging does not allow

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for a confident diagnosis to be made.

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So really where we're going to start off this

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case series is to talk mostly about anatomy.

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Anatomy is important because it allows

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us to really establish a language

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whereby we can communicate the location

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of lesions to our referring providers.

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Thereafter, we'll spend some time talking

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about imaging features of cirrhosis.

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And this becomes important because many of

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the patients who develop the most common

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primary malignant liver lesion, which

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is HCC, will have underlying cirrhosis.

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So it's important to know what that looks like.

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We'll talk about some common non-

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malignant nodules seen in the context

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of patients who have cirrhosis, as

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well as signs of portal hypertension.

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All important things to evaluate in

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any patient who's being evaluated

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for hepatocellular carcinoma.

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We'll then move on to talk specifically about

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hepatocellular carcinomas, to talk about

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it in the context of the LI-RADS lexicon.

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So we'll spend quite a bit of time going

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through that lexicon and applying the

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features of that lexicon to a whole

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variety of liver lesions which may or may

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not reflect hepatocellular carcinomas.

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We'll then follow up with evaluation of

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how to look at liver lesions post local

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regional therapy, and this also has a

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LI-RADS lexicon associated with that,

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so we'll talk a little bit about that.

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Towards the end of this, uh, video series, we'll

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finish off by talking about imaging appearance

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of some other liver malignancies, specifically

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cholangiocarcinoma and metastatic disease.