IMAGING OF ENDOMETRIOSIS
KINKEL, KAREN

Endometriosis is defined by ectopic growth of endometrial glandular tissue associated with stromal tissue. Clinical symptoms are chronic pelvic pain, mainly during menstruation, and infertility. Endometriosis of the pelvis includes endometriomas or endometriosis of the ovary, superficial and deep peritoneal endometriosis which can be located posteriorly (retrocervical (torus uteri), uterosacral ligaments, rectosigmoid, ureter), anteriorly (bladder) or in the vagina. Ultrasound is the initial imaging of choice. Characteristic sonographic features of endometriomas are diffuse, low-level internal echoes, multilocularity and hyperechoic foci in the wall. Differential diagnoses include corpus luteum, teratoma, cystadenoma, ovarian fibroid, tubo-ovarian abscess and carcinoma. Repeated ultrasound is highly recommended for unilocular cysts with low-level internal echoes to differentiate functional corpus luteum from neoplastic ovarian cysts such as endometriomas. Ultrasound is limited in the diagnosis of vaginal and posterior endometriosis. MRI has shown a high positive predictive value for all locations of pelvic endometriosis and often demonstrates abnormal nodular structures of T2 low or intermediated signal intensity with occasional T1 hyperintense spots. Knowledge of the most frequent anatomical location of endometriosis and a technical imaging protocol adapted to clinical symptoms are important factors to identify lesions of deep endometriosis, often missed at laparoscopy due to subperitoneal location or presence of severe adhesions.(...)