Three-dimensional ultrasound imaging for discrimination between benign and malignant endometrium in women with postmenopausal bleeding and sonographic endometrial thickness of at least 4.5 mm.

OBJECTIVES

To determine whether endometrial volume or power Doppler indices as measured by three-dimensional (3D) ultrasound imaging can discriminate between benign and malignant endometrium, to compare their diagnostic performance with that of endometrial thickness measurement using two-dimensional (2D) ultrasound examination, and to determine whether power Doppler indices add any diagnostic information to endometrial thickness or volume.

METHODS

Sixty-two patients with postmenopausal bleeding and endometrial thickness > or = 4.5 mm underwent transvaginal 2D gray-scale and 3D power Doppler ultrasound examination of the corpus uteri. The endometrial volume was calculated, along with the vascularization index (VI), flow index and vascularization flow index (VFI) in the endometrium and in a 2-mm 'shell' surrounding the endometrium. The 'gold standard' was the histological diagnosis of the endometrium obtained by hysteroscopic resection of focal lesions, dilatation and curettage or hysterectomy. Receiver-operating characteristics (ROC) curves were drawn for all measurements to evaluate their ability to distinguish between benign and malignant endometrium. Multivariate logistic regression analysis was used to create mathematical models to estimate the risk of endometrial malignancy.

RESULTS

There were 49 benign and 13 malignant endometria. Endometrial thickness and volume were significantly larger in malignant than in benign endometria, and flow indices in the endometrium and endometrial shell were significantly higher. The area under the ROC curve (AUC) of endometrial thickness was 0.82, that of endometrial volume 0.78, and that of the two best power Doppler variables (VI and VFI in the endometrium) 0.82 and 0.82. The best logistic regression model for predicting malignancy contained the variables endometrial thickness (odds ratio 1.2; 95% CI, 1.04-1.30; P = 0.004) and VI in the endometrial 'shell' (odds ratio 1.1; 95% CI, 1.02-1.23; P = 0.01). Its AUC was 0.86. Using its mathematically optimal risk cut-off value (0.22), the model correctly classified seven more benign cases but two fewer malignant cases than the best endometrial thickness cut-off (11.8 mm). Models containing endometrial volume and flow indices performed less well than did endometrial thickness alone (AUC, 0.79 vs. 0.82).

CONCLUSIONS

The diagnostic performance for discrimination between benign and malignant endometrium of 3D ultrasound imaging was not superior to that of endometrial thickness as measured by 2D ultrasound examination, and 3D power Doppler imaging added little to endometrial thickness or volume.