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Pattern 1 – Ovarian Endometrioma

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So, pattern one is the ovarian endometrioma.

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And even though it's the one that we most

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commonly learn about, it can happen in as few

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as 30 percent of patients with endometriosis.

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But once you have one endometrioma,

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the risk of an endometrioma on the

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contralateral ovary is pretty high.

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It's about 30 to 50%.

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And we're aware of that

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classic ultrasound appearance.

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The circumscribed hypoechoic, low-level

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internal echoes, ground glass, et cetera,

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with posterior acoustic enhancement.

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Now, how about the MRI characteristics?

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Well, this is where having the T1 with

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and without fat sat is really important.

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So on the top image here, you can see

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this patient has bilateral endometriomas

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and they're really, really bright on

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T1-weighted images with fat saturation,

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which shows that this is hemorrhage.

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T1. On T2, we see something called shading.

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So on this image here, you can see that the

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endometrioma has pretty low to intermediate

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T2 signal and it's pretty diffuse.

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So why that happens is because the blood product

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within the ovary has a decrease in free water

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content, and they're kind of changing over

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time, but the free water content reduces, and

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then we've got blood products which settle.

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So sometimes you might see different layering

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of that T2 signal depending on the stage of the

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blood product breakdown, but the whole mass can

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also have T2 shading as we see in this case.

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And typically, hemorrhagic cysts

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do not have T2 shading because

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they tend to resolve on their own.

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So the blood product breaks down

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and then is resorbed by the body.

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Whereas in endometrioma, the blood

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product kind of stays within the lesion

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and then it tends to evolve over time.

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And that's why you get that T2 shading

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just based on the hemosiderin content.

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So typically, hemorrhagic cysts don't have this.

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It's not impossible for hemorrhagic cysts

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

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So on the T1 Fatsat and T2-weighted images,

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we want to look at the ovaries, obviously,

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but we also want to look at the extraovarian

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foci using that compartment-based model.

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And again, we'll go into that

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in a little bit more detail.

Report

Faculty

Zahra Kassam, MD, FRCPC

Associate Professor of Medical Imaging, Division Head of Body Imaging

Western University

Tags

Vascular

Uterus

Ultrasound

Pelvic Wall and Floor

Ovaries

Non-infectious Inflammatory

Neoplastic

Mammography

Idiopathic

Gynecologic (GYN)

CT

Body

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