Uterine Endometrial Pathology
Endometrial thickening seen at ultrasound is a nonspecifc fnding. For years, endometrial biopsy was the diagnostic standard for differentiating benign causes, such as polyps and leiomyomas, from endometrial carcinoma. However, benign abnormalities far outnumber cancer in these situations. Other problems with biopsy include vaginal or cervical stenosis and diffculty in obtaining an adequate specimen. MRI can be helpful in further differentiating these lesions.
Endometrial polyps typically present with postmenopausal bleeding, particularly in patients on tamoxifen therapy. Transvaginal ultrasound has high sensitivity and specifcity for endometrial polyps.[31,32] Sonohysterography is the most sensitive and specifc imaging modality.
On MRI, endometrial polyps are of intermediate signal intensity on T1W images and of intermediate-to-high signal intensity on T2W images. Their signal intensity on T2W images tends to be higher than that seen in endometrial carcinoma. The presence of a central focus of low signal intensity on T2W images indicates a fbrous core, which suggests the diagnosis of an endometrial polyp (Figure 12). They are also more likely than endometrial carcinoma to contain intramural cysts,[32,33,34] which appear as smooth-walled, well-defned cystic structures of high signal intensity on T2W images. However, these cysts may also be observed in endometrial carcinoma. Utilizing contrast enhancement signifcantly improves lesion detection. However, enhancement patterns do not reliably distinguish endometrial carcinoma from other lesions. Although these imaging features can help distinguish polyps from endometrial carcinoma, it is often not specifc enough to avoid the need for biopsy. Moreover, these 2 conditions frequently coexist.[34,35]
Endometrial polyps. (A) A sagittal T2-weighted fast spin-echo fat-suppressed image. (B) An axial T1-weighted (T1W) 3-dimensional (3D) gradient-recalled echo (GRE) fat-suppressed precontrast image. (C) An axial T1W 3D GRE fat-suppressed postcontrast image shows thickening of the endometrium by a cystic lesion (arrowheads in A and C) with lacelike enhancement. This was surgically proven to be an endometrial polyp.
Appl Radiol. 2008;37(1):9-24. © 2008 Anderson Publishing, Ltd.
Cite this: Imaging the Female Pelvis: When Should MRI be Considered? - Medscape - Jan 01, 2008.