Detection of Contralateral Normal Ovary in Patients with Large(>10 cm) Unilateral Ovarian Mass by Using MRI

Purpose: To assess the usefulness of MRI for determining the presence of a large (>10 cm) unilateral ovarian tumor by detecting the existence of a normal contralateral ovary, and to establish the difference in detection rates between premenopausal and postmenopausal women, and benign and malignant tumors. Materials and Methods: Forty-two patients who underwent MR imaging and in whom the intraoperative gross and pathologic findings indicated the preseace of a unilateral ovarian mass and a normal contralateral ovary were included in this study. The images obtained were retrospectively analyzed by two radiologists, who determined the detection rate of the normal contralateral ovary and whether this differed between premenopausal and postmenopausal women, and benign and malignant tumors. Results: Contralateral normal ovaries were detected in 35 (83.3%) of 42 patients [22 of 23 ovaries (95.7%) in premenopausal women and 13 of 19 (68.4%) in postmenopausal women], with a statistically significant difference (p=0.018). Twelve of 16 of these ovaries (75%) were present in women with malignant tumors, and 23 (88.5%) of 26 in those with benign tumors, but the difference was not statistically significant (p=0.256). Conclusion: MR imaging is useful for detecting a normal contralateral ovary and for determining the site at which a large (>10 cm) unilateral ovarian tumor originates, especially in premenopausal women.