Evaluation of endometrial thickness in postmenopausal women by using 3.0-T MRI

Abstract

Background: The accepted threshold for normal endometrial thickness is 5 mm; lesions with endometrial thickness 5 mm areconsidered malignant. However, endometrium ≥ 5 mm on transvaginal ultrasonography inpostmenopausal woman is considered as asymptomatic endometrial thickening. However, recent studies suggest that asymptomatic endometrial thickness of even 8 mm – 11 mm in postmenopausal women may be normal. Objectives: The present study investigated the normal endometrial thickness range in 297 asymptomatic postmenopausal women using 3.0-T magnetic resonance imaging (MRI) T2-weighted sagittal images measured retrospectively by a single radiologist. Method: The data were classified according to patient age and postmenopausal duration, and the medical records and follow-up MR images were reviewed to assess the clinical outcome. Results: The mean endometrial thickness was 2.4 ± 0.1 mm (range: 0.1–11.6). The endometriumin 21 of 297 subjects was ≥ 5 mm thick. Follow-up MR images were obtained in 17 of these 21 women, and their endometrial thickness was found to have decreased in all of them. To date,none of the subjects has been diagnosed with endometrial cancer. Conclusion: Although 5 mm is considered the conservative threshold of normal endometrial thickness on MRI of postmenopausal women, this figure should not, to avoid excessive false-positive diagnoses, be assumed as an indication of malignancy.