0:00

This next patient is a 60-year-old male who

0:02

presents with right upper quadrant pain, fever,

0:05

and an indeterminate mass seen on ultrasound.

0:07

So, an MRI was requested for further evaluation.

0:10

So, we'll start off with our T2-weighted sequences.

0:13

As we scroll down, we can see that there

0:14

is a mass in the right hepatic lobe.

0:17

On the T2-weighted sequences performed

0:19

without fat saturation, we can see the mass

0:21

over here, at least 5 centimeters in size.

0:24

Heterogeneous signals seen within it.

0:25

Certainly, there are areas of brighter signal

0:27

around in the periphery, and internally, maybe a

0:30

little bit darker signal on the T2-weighted images.

0:33

On the T2-weighted turbo spin echo sequences with

0:35

fat saturation, where we're looking really at

0:38

the T2 content of this lesion, we can see that

0:40

overall, it has quite hyperintense T2 content.

0:44

Some of it's more hypointense, seen centrally.

0:47

And the other thing we can note on, particularly

0:49

on the, uh, fat-saturated image is that surrounding

0:52

this lesion, there is a very subtle region of

0:55

hyperintense T2 signal over here and over here.

0:59

If we were to scroll through this, you could see this

1:01

sort of signal really surrounding this lesion on many

1:05

of the, um, images on the fat-saturated sequences.

1:08

So, we'll talk a little bit about what that

1:10

could represent towards the end of the case.

1:13

We'll then move on to the T1 in and out of

1:15

phase sequence to see if this contains any

1:17

fat or any areas of increased susceptibility.

1:20

Here we have the out-of-phase sequence, here we have

1:22

the in-phase sequence, and this mass really does

1:25

look identical in both imaging sequences in that it

1:27

is T1 hypointense, no evidence of fat within this.

1:32

And there's no areas that, uh, lose signal on the in

1:36

phase images to suggest increased susceptibility artifact.

1:39

And that becomes important in this case because things

1:42

that can result in increased susceptibility artifact

1:44

include metallic clips as well as the presence of gas.

1:52

Next sequence we need to look at is the pre-

1:54

contrast imaging sequence seen over here.

1:57

This is a T1 Fatsat pre-contrast sequence, and

2:01

this again shows this lesion, the right hepatic

2:03

lobe, T1 hypointense on this imaging sequence,

2:06

no areas of hyperintense signal within it.

2:09

And last, but certainly not least, we need to

2:11

look at the post-contrast imaging sequences.

2:13

As we scroll through them, we notice that this

2:16

lesion has a very, very heterogeneous enhancement.

2:18

On the arterial phase images, there's certainly

2:21

rim enhancement surrounding this lesion over here.

2:24

And there are multiple irregular septations

2:26

within it that are also enhancing.

2:28

There are also some components internally

2:30

that demonstrate no enhancement.

2:33

We also notice on the arterial phase images that

2:36

there are very ill-defined regions of arterial

2:39

hyper-enhancement that surround this lesion.

2:42

So they surround the immediate aspect of the lesion, they

2:45

spread a little bit to the adjacent liver parenchyma.

2:48

On the portal venous phase, that enhancement persists,

2:51

at least that enhancement involving the lesion.

2:53

Thank you.

2:54

Thick rim enhancement over here, thick

2:56

septations within this, very complex, again,

2:58

areas that also demonstrate no enhancement.

3:02

These findings are also nicely demonstrated on the

3:04

equilibrium phase images, rim enhancement, septal

3:07

enhancement within it, areas of non-enhancement.

3:10

That ill-defined arterial hyper-enhancement that we saw here

3:13

becomes more iso-intense on the portal venous phase images,

3:17

and on the equilibrium phase images as well.

3:20

Summarizing the imaging findings that we see

3:22

here is that we have a mass in the right hepatic

3:25

lobe, quite heterogeneous T2 signal within it.

3:29

Post-contrast, there is rib enhancement,

3:31

certain areas within it have septal

3:33

enhancement, certain other areas are avascular.

3:37

On the T2-weighted fat-saturated sequence, we can

3:40

see that surrounding this lesion there is mild

3:42

hyperintensity T2 signal corresponding to that to

3:45

a certain degree on the arterial phase images.

3:47

There is arterial hyperenhancement surrounding this

3:50

lesion. Somebody comes in with a right upper quadrant

3:53

pain, fever, and a lesion that looks like this. You've got

3:56

to think about the presence of an abscess, and this turns

3:59

out to be a pyogenic abscess. Most liver abscesses in

4:03

the liver will be pyogenic abscesses, about 90 percent

4:06

of cases. A smaller amount will be amoebic abscesses, and

4:09

these are often referred to as somewhat difficult to

4:11

differentiate from pyogenic abscesses, but often amoebic

4:14

abscesses are more solitary, while pyogenic ones

4:17

will have numerous abscesses within the liver.

4:21

There's something called a cluster sign, where

4:23

you see a cluster of liver abscesses coalesce

4:26

to one another to make a bigger one over the

4:28

course of several serial imaging studies.

4:31

Another type of abscess that can

4:33

afflict the liver are fungal abscesses.

4:35

These tend to be much smaller, in the range

4:37

of about one centimeter or less in size.

4:40

Scattered throughout the liver, and we often also see

4:43

these in the spleen, so you're going to look in a few

4:46

different organs to see if these are present to suggest

4:49

that fungal abscesses are the inciting etiology.

4:53

We, of course, also typically see some fungal abscesses

4:56

in patients who have a decreased immune function.