MR imaging appearance of the uterus in postmenopausal women receiving tamoxifen therapy for breast cancer: histopathologic correlation

PURPOSE: To describe the spin-echo and dynamic gadolinium-enhanced magnetic resonance (MR) imaging appearance of the uterus in women receiving tamoxifen. MATERIALS AND METHODS: Thirty-five postmenopausal women with breast carcinoma receiving tamoxifen therapy underwent pelvic MR imaging. T1-weighted, T2-weighted, and dynamic gradient-echo T1-weighted sequences were used. Twenty-seven patients underwent uterine sampling within 3 months of MR imaging. RESULTS: Endometrial width on T2-weighted images ranged from 0.1 to 7.5 cm (mean thickness, 1.1 cm). Two uterine imaging patterns were noted. Patients with pattern 1 findings had homogeneous high signal intensity of the endometrium on T2-weighted images (mean, 0.5 cm) and enhancement of the endometrial-myometrial interface and a signal void in the lumen on gadolinium-enhanced images (18 patients). Patients with pattern 2 findings had heterogeneous endometrial signal intensity on T2-weighted images (mean, 1.8 cm) with enhancement of the endometrial-myometrial interface and latticelike enhancement traversing the endometrial canal on gadolinium-enhanced images (17 patients). Other imaging findings included subendometrial cysts, nabothian cysts, leiomyoma, and adenomyosis. Ten patients with pattern 1 findings had atrophic or proliferative endometria at histopathologic analysis; 12 of the 17 patients with pattern 2 findings had polyps, one of which had a focus of endometrial carcinoma. CONCLUSION: MR imaging of the uterus showed two distinct patterns in women receiving tamoxifen therapy.