Value of intra-adnexal and extra-adnexal computed tomographic imaging features diagnosing torsion of adnexal tumor

The objective of this study was to evaluate the usefulness of the intra-adnexal and extra-adnexal computed tomographic (CT) features in identifying adnexal torsion. We retrospectively analyzed CT examinations of 38 adnexal masses with torsion and 270 without torsion, which has been surgicopathologically confirmed. The CT features were evaluated according to 2 categorized groups. The first group included the intra-adnexal features dealing with the ovary and uterine tube, whereas the other included the extra-adnexal features dealing with changes of adjacent anatomical structures such as the uterus, gonadal vein, and peritumoral zone. We acquired statistical proportions for the frequencies of these 2 groups of CT features in ovarian tumors with adnexal torsion versus those without adnexal torsion. When there were intra-adnexal CT features of adnexal torsion, peculiar uterine tube thickening was identified in 74% of the lesions, eccentric or concentric wall thickening in 54% (of only cystic lesions), eccentric septal thickening in 50% (of only cystic lesions except mature cystic teratoma), and eccentric or diffuse decreased or poor contrast enhancement of the internal solid component or thickened wall in 50%. In extra-adnexal CT features of adnexal torsion, uterine deviation to the twisted side was identified in 61% of the lesions, peritumoral infiltration in 40%, nonvisualized anatomic continuity of the ipsilateral gonadal vein with the twisted adnexal mass in 71%, and ascites in 13%. There were significant differences in all of the intra-adnexal and extra-adnexal CT findings, except for ascites, between twisted and nontwisted adnexal tumors. The intra-adnexal and extra-adnexal groups of CT features are valuable in identifying torsion of adnexal mass.