Magnetic resonance evaluation of adnexal masses.

BACKGROUND Accurate evaluation of adnexal masses allows correct surgical procedure, avoiding unnecessary surgery. PURPOSE To evaluate the accuracy of magnetic resonance imaging (MRI) in the diagnosis of malignancy of adnexal lesions. MATERIAL AND METHODS We retrospectively reviewed the pelvic MRI scans of 161 patients with 199 surgically confirmed adnexal masses, between November 1998 and June 2005. The criteria for adnexal malignancy were contrast-enhanced solid lesions, contrast-enhanced solid components in mixed lesions (except those with low-signal-intensity solid components on T2-weighted imaging [T2WI]), contrast-enhanced papillary projections in cystic lesions (except those with low-signal-intensity papillary projections on T2WI), or septal thickness >or=3 mm. Ascites, peritoneal metastasis, and pelvic adenopathy were also regarded as criteria for malignancy. RESULTS On MRI evaluation, 97 adnexal lesions were malignant and 102 were non-malignant. Thirty-two percent of patients with ascites had benign lesions. Histopathologic evaluation of the adnexal lesions showed that 83 were malignant (true positives), 100 were non-malignant (true negatives), and seven were uncertain malignant potential tumors; two were false negative and seven were false positive. The MRI sensitivity and specificity for malignancy were 98% and 93%, respectively. MRI reached an accuracy of 95%, with a positive predictive value of 0.92 and a negative predictive value of 0.98 for malignant adnexal lesions. The kappa coefficient was 0.906, indicating almost perfect agreement between MRI and histological results. CONCLUSION MRI is an accurate method for evaluating the malignancy of adnexal lesions.