0:01

Okay, so teratoma, this is a very interesting

0:03

tumour that is actually quite common.

0:06

It's a type of germ cell tumour which is composed

0:09

of mesodermal, endodermal, and ectodermal

0:12

tissues, and it does have very unique imaging

0:15

features on MRI and on CT as well, but MRI has a

0:20

few more features, and that is characterized by

0:23

the presence of intratumoral fat or lipid, and

0:26

we might see a fat-fluid or a fat-fatty level.

0:30

So we will go through that in a little

0:32

bit more detail in just a moment.

0:34

So on CT, this is one of my most interesting

0:37

teratoma cases from several years ago.

0:39

This is a 38-year-old woman.

0:41

And she has bilateral teratomas.

0:43

So you can see the right ovary is huge.

0:46

And then we've got fat within this lesion.

0:49

And we've got a similar-looking

0:51

lesion on the left side.

0:53

And I don't know, when I looked at this case

0:55

initially, I thought maybe these look like

0:57

little brains with the ventricles developing.

1:00

So it was a very unusual appearance.

1:02

But as you looked a little bit more

1:03

superiorly, there was fluids in the

1:06

perisplenic space and the splenocolic ligament.

1:09

And then as we progressed more superiorly

1:13

from the right ovarian mass, the wall

1:15

looked a little bit more thick and,

1:17

um, maybe some solid components in it.

1:19

So this is a more sinister-looking mass.

1:21

So maybe that right ovary was teratous,

1:24

or maybe there was malignant

1:25

degeneration of one of those lesions.

1:27

So those are important things

1:29

to keep in mind as well.

1:30

On MRI, again, the technique is quite important.

1:34

We want to make sure that we include

1:36

T1-weighted images with and without

1:38

fat saturation, because obviously we're

1:40

looking at the signal characteristics

1:42

and the composition of the lesion.

1:44

So if there is fat within the

1:46

lesion, we know that this is a teratoma.

1:48

A neat clue that not many people use

1:49

is one that's created by an artifact.

1:51

So because the teratoma contains both

1:55

fluid and fat content, we can actually

1:58

see chemical shift that develops.

2:01

And that's manifested by alternating

2:04

dark and bright T2 signal lines in

2:07

the frequency-encoding direction.

2:12

So even if, for example, your fat saturation

2:15

didn't work or didn't look very good, you can

2:17

look at the T2-weighted images and look for

2:20

these alternating bands of dark and bright

2:23

signal that we see here, and that indicates that

2:26

there's both fat and water within the lesion.

2:29

And then we know that the frequency

2:30

encoding direction is going from left to

2:33

right because the fat and water frequencies

2:35

are being separated in that direction.

2:38

Typically, we don't require gadolinium

2:41

unless there's concern for malignant

2:42

transformation, but that's totally institution

2:45

dependent and up to your own preference.

2:47

In and out of phase is rarely helpful.

2:50

Because we're looking at macroscopic fat and

2:53

not dissolved fat or intracellular lipid.

2:56

So the complications of teratoma, I

2:59

showed you on the last set of images,

3:01

and I'll just go back to those briefly.

3:03

We've got some free fluid here, so

3:05

maybe a chemical peritonitis, possibly a

3:07

rupture from one of those ovarian lesions.

3:10

Anytime you have a large ovarian mass, there's

3:12

a risk of it twisting on its pedicle, causing

3:14

torsion, and then malignant transformation

3:17

would be the other main complication.