0:01

So, pattern one is the ovarian endometrioma.

0:04

And even though it's the one that we most

0:06

commonly learn about, it can happen in as few

0:09

as 30 percent of patients with endometriosis.

0:12

But once you have one endometrioma,

0:14

the risk of an endometrioma on the

0:16

contralateral ovary is pretty high.

0:18

It's about 30 to 50%.

0:20

And we're aware of that

0:22

classic ultrasound appearance.

0:23

The circumscribed hypoechoic, low-level

0:26

internal echoes, ground glass, et cetera,

0:29

with posterior acoustic enhancement.

0:32

Now, how about the MRI characteristics?

0:34

Well, this is where having the T1 with

0:36

and without fat sat is really important.

0:39

So on the top image here, you can see

0:41

this patient has bilateral endometriomas

0:44

and they're really, really bright on

0:46

T1-weighted images with fat saturation,

0:49

which shows that this is hemorrhage.

0:51

T1. On T2, we see something called shading.

0:54

So on this image here, you can see that the

0:57

endometrioma has pretty low to intermediate

1:00

T2 signal and it's pretty diffuse.

1:03

So why that happens is because the blood product

1:06

within the ovary has a decrease in free water

1:10

content, and they're kind of changing over

1:11

time, but the free water content reduces, and

1:15

then we've got blood products which settle.

1:17

So sometimes you might see different layering

1:20

of that T2 signal depending on the stage of the

1:24

blood product breakdown, but the whole mass can

1:27

also have T2 shading as we see in this case.

1:30

And typically, hemorrhagic cysts

1:32

do not have T2 shading because

1:34

they tend to resolve on their own.

1:37

So the blood product breaks down

1:38

and then is resorbed by the body.

1:41

Whereas in endometrioma, the blood

1:42

product kind of stays within the lesion

1:45

and then it tends to evolve over time.

1:48

And that's why you get that T2 shading

1:50

just based on the hemosiderin content.

1:52

So typically, hemorrhagic cysts don't have this.

1:55

It's not impossible for hemorrhagic cysts

1:57

to have T2 shading, but it's not common.

2:00

So on the T1 Fatsat and T2-weighted images,

2:04

we want to look at the ovaries, obviously,

2:06

but we also want to look at the extraovarian

2:09

foci using that compartment-based model.

2:12

And again, we'll go into that

2:13

in a little bit more detail.