MR imaging of endometrial benign and malignant polypoid lesions: correlations with clinicopathological findings

Objective: To investigate the diagnostic value of conventional and dynamic gadolinium- enhanced T1-weighted (T1W) MRI in benign and malignant endometrial polypoid lesions. The pathologic basis of MRI features was also evaluated. Methods: The conventional and dynamic contrast enhanced MRI features in 48 cases with clinicopathologically-proved endometrial polypoid lesions were retrospectively analyzed, including 26 cases with malignant tumors (23 cases with endometrial carcinoma and 3 cases with endometrial sarcoma) and 22 cases with benign polypoid lesions (12 cases with endothelial polyps and 10 cases with submucous leiomyomas). The occurrence probability of central fibrous core, intratumoral cysts and intact junctional zone were evaluated by Fisher's exact test. Results: Benign and malignant endometrial polypoid lesions had specific characteristics on MRI. Endometrial carcinomas usually appeared as homogeneous intermediate or slighfiy high signal-intensity masses on T2-weighted images, and relatively homogeneous hypodense masses on contrast-enhanced images with myometrial invasion (P < 0.05). An irregular central fibrous core and small non-enhanced intratumoral cysts were seen more frequently in endometrial polyps (P<0.05) than others. All 3 cases with uterine sarcomas showed obviously inhomogeneous intensity on T2WI and demonstrated areas of early and persistent marked enhancement. Submueous leiomyomas demonstrated isodense or slightly low-density masses with defined outline on T2WI and the endomerium was displaced. The diagnostic sensitivity, specificity and accuracy of malignant polypoid masses were 92.3% (24/26), 83.3% (20/24) and 95.8% (46/48) respectively. Conclusion: Conventional and dynamic contrast-enhanced MRI are valuable in characterizing the benign and malignant endometrial polypoid lesions. (authors)