Hepatic adenoma, these are slightly less common
but can be found particularly in women of childbearing age.
The most common location is subcapsular
and it's found within the right lobe of the liver.
Often these can contain fat, necrosis, calcifications and hemorrhage
and can appear very heterogeneous because of these findings.
The development is related to estrogen containing compound
such as birth control pills. So women of childbearing age
that use birth control pills are the most likely to get these lesions.
And they can actually result in severe hemorrhage which can require surgery.
All right, so let's look at some CT and MRI images
that demonstrate the imaging characteristics of a hepatic adenoma.
We have arterial and portal venous phase CT scans here
and we have MRI scans both demonstrating
characteristic imaging of an adenoma.
Let's take a look at this in a little bit more detail.
So on a CT scan and adenoma present as a heterogeneous mass,
which enhances on the early postcontrast images
and then washes out early.
So this an arterial phase CT scan,
you can see a very subtle finding, anteriorly within the liver
and there is very subtle arterial enhancement in a portion of this finding.
The remainder of this doesn't enhance so it's somewhat heterogeneous.
On the portal venous phase the contrast washes out
and now the entire lesion appears hypodense.
Again, slightly heterogeneous with this portion of it being
a little more hyperdense than this portion.
On an MRI and adenoma is mildly T2 hyperintense
and T1 hypointense and again it appears heterogeneous.
There's enhancement on the early postcontrast images
and early washout similar to that seen on CT,
and when you look at opposed phase imaging,
their signal drop out because of the fat content within the lesion.
So here's an in phase and an opposed phase MRI image.
You can see the lesion right here, it's hypointense on the MRI
in phase. However, in the opposed phase
that actually loses even more signal and becomes more hypointense
and this is again characteristic of an adenoma,
because it does contain areas of lipid.
On a T2 weighted MRI image, the adenoma appear slightly hyperintense.
On an ultrasound, it's a very nonspecific heterogeneous mass.
So again, anytime a mass is seen on ultrasound, it really needs a CT
or an MRI with contrast for better characterization.
Focal nodular hyperplasia is another lesion
that?s somewhat uncommonly found within the liver.
It results from an anomaly of the arterial blood supply
which results in hyperplastic growth of the liver parenchyma.
Oral contraceptives may promote growth,
but they don't cause the development of it
which is unlike an adenoma where all oral contraceptives
actually do cause the development.
These can occur anywhere within the liver.
So an ultrasound, a focal nodular hyperplasia lesion
appears as a homogeneous isoechoic mass
that has a hypoechoic central scar.
And on CT it actually present an isodense mass,
which is difficult to see on the non-contrast images.
It has intense homogeneous enhancement on the postcontrast imaging
and the key feature of a focal nodular hyperplasia,
is that it has a central non-enhancing scar.
Gradually this become isodense on delayed imaging
with a central scar becoming more hyperdense.
On MRI, these are isointense on T1 and T2 weighted images
and the central scar is dark on both T1 and bright on T2.
There's homogeneous enhancement on the postcontrast imaging,
and gradually this becomes isointense on delayed imaging
with a central scar becoming a little more hyperintense.
So let's take a look at an example.
Here we have a T1 contrast enhanced study
and you can see that there is homogeneous enhancement of the lesion.
However, the central scar is hypointense which is characteristic.
On T2 weighted imaging, it's somewhat isointense
to the rest of the liver parenchyma, but the central scar
is actually slightly hyperintense.
Again, characteristic of a focal nodular hyperplasia.
So let's go back to the case that we looked at initially,
we have 3 MRI images and we have the first one
which is a precontrast T1 image that demonstrates a liver lesion here.
The second image is an axial postcontrast image,
and the third is also a postcontrast image.
However, it's done with a 10-minute delay.
So what is your differential diagnosis here?
Will take a look at each of this in a little more detail.
So in this image on the initial precontrast image,
you can see that there is peripheral enhancement.
However, it's heterogeneous
because the central portion is really not enhancing.
On the delayed images the entire lesion is now filled in with contrast.
So this represents a cavernous hemangioma.
It's hypointense on the T1 precontrast images.
It has peripheral nodular enhancement on the early postcontrast image
and then on the delayed images there's fill-in
and this is typical again of a cavernous hemangioma,
which is a benign finding and no further work of needs to be performed.
So we've gone over multiple different benign liver lesions
as well as diffuse liver disease.
Hopefully this will help you as we go forward with further lesions
within the liver to help you characterize what's benign and what's malignant.