0:01

Another manifestation of pattern three is

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rectosigmoid involvement, and many of us

0:06

may have learned about this when we're

0:09

reviewing barium enema cases, for example.

0:11

Sometimes you can see an indentation of

0:14

the rectal wall anteriorly because of a

0:16

deposit of endometriosis, and that's what

0:19

rectosigmoid involvement typically looks like.

0:21

So it's usually the anterior rectal

0:23

wall that's most commonly involved.

0:25

It may involve up to 40% of the

0:28

luminal circumference of the rectum.

0:30

And we might see something

0:31

called a mushroom cap sign.

0:33

So I'll show you that in just a moment.

0:36

Typically, what we see is an area of low

0:38

T2 signal again, because it's fibrosis

0:41

and hypertrophy of the muscularis propria

0:44

of the rectum, which gives us that look.