So in this lecture we?ll be discussing some common malignant lesions
that can be found within the liver.
Let?s take a look at these three CT images.
Keep these three images in mind as we go through this lecture.
So the 2 most common liver malignancies are metastases
and hepatocelular carcinoma.
Metastases are actually the most common malignancy found within the liver.
If you take a look at this pathological specimen
you can see multiple masses throughout the liver and these represent metastases.
The most common organ of origin is the GI tract, particularly the colon.
Other common sites of origin include the breast, lung, and melanoma.
So how can you recognize a metastases on an imaging study?
Usually, they come up as multiple low to intermediate density masses
with slightly ill-defined margins.
They also demonstrate very variable enhancement after contrast administration.
Contrast-enhanced MRI and CT are about equally sensitive
in the detection of metastases within the liver.
So let?s take a look at this CT scan. This is a non-contrast enhanced CT
and it demonstrates multiple calcified metastases
within the liver from a colon adenocarcinoma.
On the same patient, when you give contrast the contrast-enhanced CT
actually shows multiple other masses
that now demonstrate heterogeneous enhancement.
Let?s take a better look at this. So this is the non-contrast enhanced CT,
you can see a couple of different masses with calcifications within it.
The high density here is calcification as we have not yet given contrast.
On this contrast-enhanced study you can see multiple, multiple, masses
a lot more than you can see on the non-contrast examination
and many of them demonstrate rim enhancement,
some of them demonstrate central enhancement,
so very variable enhancement actually.
Hepatocellular carcinoma is the second most common malignancy
found within the liver.
About 80% of hepatocellular carcinoma cases are associated
with either hepatic cirrhosis or hepatitis B or C.
Usually, hepatocellular carcinoma presents as a solitary mass,
although occasionally it may present as multiple masses.
So this is an example of a CT demonstrating hepatocellular carcinoma.
This is a coronal arterial phase CT
which demonstrates a heterogeneously enhancing mass
that has prominent vascularity.
This entire portion of the liver looks like it?s abnormal
and you can see multiple vessels within it.
On the portal venous phase you have washout of the enhancement,
so now you see a very large mass with very little enhancement left within it.
And this is very typical of a hepatocellular carcinoma.
It demonstrates arterial phase enhancement
and then washout in the portal venous phase, so early washout.
Most often a hepatocellular carcinoma presents as a hypodense
or isodense lesion on a non-contrast CT so this can be a very vague finding.
Early enhancement in the arterial phase is seen as we just saw
and we can have early washout on the portal venous and delayed phases.
Hepatocellular carcinomas can occur anywhere within the liver.
An MRI is actually a lot more sensitive as there are certain features
that are really seen only on MRI and not really seen on CT.
So what are the MRI features of hepatocellular carcinoma?
It usually presents as a hypointense mass on T1 weighted images.
It demonstrate mild hyperintensity on the T2 weighted images
and may contain cystic or necrotic areas that are seen on T1 and T2 images
and they are T1 hypointense and T2 hyperintense
so it presents us a very heterogeneous mass even on MRI.
Post-contrast images demonstrates heterogeneous enhancement
as they do on the CT that we just saw.
Usually, a biopsy has to be performed in order to really prove
what the lesion is so a definite diagnosis really can?t be made just by imaging.
It really does need a biopsy and biopsies can be performed
using either ultrasound or a CT guidance. So let?s take a look at this case.
There?s a liver lesion on the portal venous phase.
Can you describe what the findings are?
Let?s take a look at the lesion and let?s take a look at everything else
that?s on this exam that might help us better characterize
with this lesion represents.
So there?s a low density lesion within the right lobe of the liver,
we can see it right here relatively well circumscribed.
Associated findings include ascites so there is a lot of fluid
surrounding the liver here that?s low density
and you can see nodularity of the liver contour.
There?s a little bit of fluid around the spleen as well here.
So given the associated findings of hepatic cirrhosis,
this lesion most likely represents a hepatocellular carcinoma
and as you remember on the portal venous phase the lesion washes out
and may not demonstrate enhancement.
So let?s go back to that initial case that we saw when we began the lecture.
So what CT phases are depicted here?
What do you think the imaging findings are?
So the first is the non-contrast enhanced CT
so there?s no contrast administered on this one
and you can see that there is a low density lesion near the hilum of the liver.
The second is an arterial phase which demonstrates an enhancing mass
also at the hilum of the liver and on the portal venous phase,
the mass demonstrates washout so very little enhancement is left here.
This actually represents a metastases.
It?s a low density, slightly irregular mass seen on a non-contrast CT image.
Again, the arterial phase demonstrates homogeneous enhancement
and it actually has what we call a central nonenhancing nidus.
So the central portion of this mass is not enhancing
the way the rest of the mass is enhancing.
In the portal venous phase you have washout of the contrast.
So although this could represent a hepatocellular carcinoma
with the early enhancement and the early washout,
homogeneous enhancement in the central nidus
are not really typical for hepatocellular carcinoma
so this most likely represents a metastases.
Again, this is one of those cases that we really can?t say a definite diagnosis of
just basing on the imaging. The patient really would need a biopsy
and this can be performed again either by ultrasound or CT guidance.
This patient actually has a known GI stromal tumor
and based on that fact we can more definitely say that
this likely represents a metastases.
So we?ve gone over some of the more common malignant liver lesions.
The 2 most common again are hepatocellular carcinoma and metastases.