**5.2 'Deep endometriosis'**

Deep endometriotic lesions are classified according to the anatomic location in the anterior compartment (bladder) or in the posterior compartment (uterosacral ligament, vagina and bowel).

Multifocality is a major characteristic of deep endometriosis, thus requiring in some cases different surgical procedures (laparoscopy and/or laparotomy) to obtain a complete exeresis and a functional improvement.

#### **5.3 Endometriosis of the bladder**

Localization of disease in the bladder is estimated in < 1% of patients.

TVUS remains the first diagnostic method in the evaluation of the ovary, generally reserving

At MRI, a large endometrioma (>1 cm in diameter) appears as a homogeneously hyperintense mass on T1 weighted MR images and show a low signal intensity on T2 weighted MR images with areas of high signal intensity. The 'shading' sign is used to differentiate endometriomas from functional hemorrhagic cysts that do not show it, which

Another diagnostic criteria for a definitive diagnosis of endometriomas is the presence of

Endometriomas are often bilateral (more than 50% of cases), multilocular or associated with interovarian adhesions; in the last case a typical MRI pattern called "kissing ovaries" could

Fig. 4. T2-weighted image acquired on the transverse plane, showing hyperintense bilateral endometrioma masses on the ovaries that are closed up due to interovarian adhesions

Deep endometriotic lesions are classified according to the anatomic location in the anterior compartment (bladder) or in the posterior compartment (uterosacral ligament, vagina and

Multifocality is a major characteristic of deep endometriosis, thus requiring in some cases different surgical procedures (laparoscopy and/or laparotomy) to obtain a complete

Fat suppression is mandatory to differentiate endometriomas from cystic teratomas.

Localization of disease in the bladder is estimated in < 1% of patients.

Adnexal localization is the most common clinical setting of endometriosis.

multiple T1 hyperintense cysts regardless of their T2 signal intensity [16].

MRI as a tool for resolving cases in which there is some doubt.

usually disappears at subsequent MRI examinations.

**5.1 Ovarian endometriosis** 

be noted (**Fig. 4**).

(Kissing ovaries).

bowel).

**5.2 'Deep endometriosis'** 

exeresis and a functional improvement.

**5.3 Endometriosis of the bladder** 

Uterus is usually anteflexed and the anterior cul-de-sac is obliterated due to extensive adhesions. The patient often complain pain, especially while urinating.

Two types of bladder endometriosis have been recognised. One develops exclusively after cesarean section and is considered to result from iatrogenic implantation of decidua. The other, a primary form, is found in women who have not previously undergone surgery on the uterus. Various hypotheses have been proposed to explain the pathogenesis in the latter case. Microscopically, the typical pattern is a focus of endometriosis scattered in the bladder wall. The main feature is the paucity of endometrial-type stroma [17].

MRI is reliable for the diagnosis of bladder endometriosis. Endocavitary coil MRI is reliable for establishing the depth of the lesions penetrating into the bladder wall [18].

On MRI images, bladder endometriosis can be diagnosed as a localized or diffuse bladder wall thickening, or as focal signal intensity abnormality. T2 and T1 weighted images can show a nodular hypointense mass usually located on the anterior upper or posterior bladder wall (**Fig. 5**).

Fig. 5. Coronal (A) and sagittal (B) T2-weighted images showing localized bladder wall thickening in the anterior upper bladder wall (blue circles). On fat suppressed T1-weighted coronal (C) and axial (D) images some high signal intensity intra-lesion spots indicating recent haemorrage.

On fat suppressed T1-weighted FLASH 2d images, some high signal intensity intralesional spots are present in some cases.

Pelvic Endometriosis: A MR Pictorial Review 455

In patients with USLs involvement adhesions could often develop thus, providing posterior displacement of the uterus and ovaries, angulation of bowel loops, elevation of the posterior vaginal fornix, and loculated fluid collections [21]. At MRI, adhesions are detected when

Endometriosis of the vagina includes lesions infiltrating the anterior rectovaginal pouch, posterior vaginal fornix and retroperitoneal area between the anterior rectovaginal pouch

MRI represents the ideal complement to physical examination and TVUS in order to predict lesion extension upward and posteriorly. Sometimes, the use of a water enema is used to

In patients with vaginal endometriosis axial and sagittal T2-weighted Turbo Spin Echo images usually show hypointense nodules. Anterior attraction of the rectum toward the torus uteri and asymmetric thickening of the rectal wall are associated to rectal wall infiltration. Determining the depth of infiltration of the rectal wall allows the gynaecologist to discuss the surgical approach (nodulectomy vs bowel resection) with the colorectal

T1-weighted images with fat suppression could demonstrate T1 isointensity of the nodule

Most patients with vaginal involvement also demonstrate obliteration of the retrouterine excavation (**Fig. 8 B, C**); in such cases the extension of the pelvic focus may lead to ureteral

Fig. 8. T1-weighted image with fat suppression demonstrates isointensity of the nodule and some small hyperintense foci, suspected for micro-haemorragies (A). Axial (B) and sagittal (C) T2-weighted image show obliteration of retrouterine escavation by an hypointense nodule, with anterior attraction of the rectum toward the torus uteri and asymmetric

Clinical symptoms of patients with endometriosis of the recto-sigmoid colon are manifested as crampy pain, flatulence, painful tenesmus, constipation, diarrhoea and bowel obstruction.

Rectosigmoid endometriosis represents 70% of cases of intestinal endometriosis.

**A B C**

surgeon. The use of the endorectal coil optimizes the finding of MRI [22].

and some small hyperintense foci, suspected for micro-haemorragies (**Fig. 8 A**).

low signal intensity is found within the ligaments.

predict the extension of the lesion toward the rectum.

**5.5 Endometriosis of the vagina** 

Patients tipycally refer dyspareunia.

infiltration and ureterohydronephrosis.

thickening of the rectal wall.

**5.6 Endometriosis of the bowel** 

and posterior vaginal fornix.
