Imaging the Female Pelvis: When Should MRI be Considered?

Jennifer Hubert, MD; Diane Bergin, MD

Disclosures

Appl Radiol. 2008;37(1):9-24. 

In This Article

Endometrial Carcinoma

Endometrial carcinoma is the fourth most common cancer in women.[36,37,38,39] The disease occurs most commonly in women in the sixth and seventh decades of life. Clinically, patients present with abnormal uterine bleeding in 75% to 90% of cases. As a result of the early clinical symptoms, patients often present with early-stage disease.[34]

Adenocarcinoma represents roughly 90% of endometrial carcinomas, with varying grades of differentiation. Other histologic subtypes include squamous, papillary, and clear-cell carcinoma. However, histology cannot be determined based on imaging characteristics.[38,39]

MRI is not recommended as a screening procedure in the diagnosis of endometrial carcinoma. However, MRI has proven to be an important tool for the staging of known endometrial carcinoma.[38] MRI can differentiate between superfcial and deep-muscle–invasive tumors by using a combination of T2W imaging and contrast-enhanced MRI. This can signifcantly alter surgical management. The presence of cervical invasion also alters preoperative and surgical management. MRI has been shown to be superior to both CT and ultrasound in assessing myometrial invasion, cervical extension, and nodal involvement.

Endometrial carcinomas appear isointense to the myometrium and endometrium on T1W images. On T2W images, their signal intensity is commonly hyperintense; however, this is quite variable.[38] Endometrial carcinomas usually enhance less than the myometrium does, with the difference less marked on delayed images. Myometrial invasion is best visualized on T2W images, where it appears as a disruption or an irregularity of the junctional zone by a mass of intermediate signal intensity (Figure 13).

Endometrial carcinoma. (A) A sagittal T2-weighted fat-suppressed image shows that an irregular mass along the anterior wall of the endometrium is invading the myometrium (arrows). (B and C) This mass is seen to enhance on postcontrast images (arrows). Note the low T2 signal and the hypoenhancing leiomyoma (arrowheads) in the anterior body of the uterus.

Transmyometrial extension of tumor is identifed by interruption of the normal low signal intensity of the serosal surface. However, early serosal invasion may be diffcult to detect. Parametrial involvement is best depicted on T1W images with a signal intensity change in the parametrial fat. T1-weighted images are also better for identifying tumor involvement of the vagina when there is disruption of the low signal intensity wall. Lymph node involvement is suggested on T1W images with nodes that have a diameter >1 cm in the short axis. MRI can also detect tumor extension outside the true pelvis as well as bladder and rectal invasion.

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