Our MRI protocol for patients suspected to have pelvic endometriosis consists of :
- axial,
sagittal and coronal T2w TSE images
- axial T2w SPAIR images
- axial T1w TSE images
- axial and sagittal T1w SPAIR images after intravenous
contrast medium injection (if necessary)
Slice thickness: 3-4 mm
- Vaginal and rectal cavities fluid distension is recommendable for a better depiction of small parietal lesions,
improving sensitivity and specificy (Fig.1)
- Contrast medium injection is not mandatory; it can help in distinguish deep endometriosis from scars,
allowing the demonstration of the activity of the disease and it can improve the sensibility of the technique when patients refused fluid distension of the cavities
- The typical histologic features of endometriotic implants are
foci of fibromuscular hyperplasia enclosing ectopic endometrial glands
- The corresponding MRI findings are (Fig.2):
- T2w hypointense plaques,
nodules or thickening
- Small hyperintese foci on T2w images due to the glandular endometrial components
- T1 hyperintese spots suggestive of haemorrhagic phenomena
- Lesions can be focal or circonferential (Fig.3) making diagnosis sometimes tricky in a not clear clinical setting; neoplastic lesion must primarily be excluded
- Sometimes only distortions and angulations of recto-sigmoid walls are visible
- Inflammatory episodes due to cyclic haemorrhage may evolve in adhesions and bowel strictures
-Rectovaginal septum lesions extends from posterior wall of the vagina to the anterior wall of the rectal muscolaris,
under the peritoneal fold of the Douglas pouch (Fig.4).
- Hourglass-shaped plaques (Fig.5) are defined as lesions expanding from posterior fornix and retrocervical area-torus uterinus toward the anterior rectal wall infiltrating its muscolaris
- The "mushroom cap" sign (Fig.5) is described as a feature of rectosigmoid endometriotic involvement.
It consists in the presence of a T2 heterogeneous hypointense mushroom cap shaped lesion,
due to hypertrophic muscolaris propria,
growing into the bowel lumen surrounded by hyperintense mucosal and submucosal layers
-In the pre-surgical setting,
radiologists should provide the following information:
- Number of lesions
- Topography ( low-,mid-,
high rectum; recto-sigmoid junction; sigmoid-colon)
- Size and lenghtof the bowel-tract involved
- Distance from the anal margin
- Depth of wall penetration (involvement of muscolaris propria)
- Double contrast barium enema and MDCT enteroclisis can be
used for preoperative planning
- Rectosigmoidal endoscopic ultrasonography seems to better
depict muscolaris layer infiltration