Myometrial invasion by endometrial carcinoma: assessment by MR imaging.

In patients with early-stage endometrial cancer, preoperative knowledge of myometrial tumor extension has important prognostic and therapeutic implications. The purpose of this prospective study was to determine the sensitivity and specificity of MR imaging for assessing the depth of myometrial invasion in patients with endometrial cancer that clinically was thought to be confined to the uterine corpus. Sixty-five consecutive patients were included in the study. All patients had MR imaging before radical surgery. MR imaging findings were compared with microscopic pathologic findings in all cases. On MR images and at histologic analysis, myometrial invasion was classified as absent (tumor confined to the endometrium), superficial (less than 50% of myometrial thickness), or deep (50% or more of myometrial thickness). At histologic examination, tumor limited to the endometrium was proved in 14 cases, superficial myometrial invasion by tumor was present in 34 cases, and deep tumor invasion was demonstrated in 17 cases. In determining the presence of tumor confined to the endometrium, MR imaging had a sensitivity of 57% and a specificity of 96%. In the assessment of tumor with superficial myometrial invasion, MR imaging had a sensitivity and a specificity of 74%, whereas in assessing deep myometrial penetration, the sensitivity and specificity of MR were 88% and 85%, respectively. Errors in MR interpretation when determining myometrial tumor spread were more frequently overestimations rather than underestimations. Our results indicate that MR imaging is useful for the preoperative assessment of myometrial invasion in patients with proved endometrial cancer.