Classification of asymptomatic adnexal masses by ultrasound, magnetic resonance imaging, and positron emission tomography

Objective. The purpose of this study was to determine the diagnostic accura cy of sonography versus magnetic resonance imaging (MRI) and positron emiss ion tomography (PET) in the characterization of adnexal masses. Methods. One hundred and one patients with asymptomatic adnexal masses, whi ch were scheduled for laparoscopy, underwent preoperative transvaginal ultr asound, MRI, and 2-[F-18]fluoro-2-deoxy-D-glucose PET. Two different sonomo rphological scoring systems were used to distinguish malignant from benign lesions. In addition, transvaginal Doppler flow velocimetry was performed a nd the resistance index (RI) of ovarian blood vessels was calculated. RI va lues below 0.45 were considered to indicate malignancy. MRI was evaluated o n the basis of signal intensity and morphologic features such as wall thick ness, septations, fluid or solid components, and vascularity. PET imaging w as used to determine 2-[F-18]fluoro-2-deoxy-D-glucose uptake. Malignancy wa s suspected if radiotracer uptake equaled or exceeded that of the liver. Ba sed on histologic findings, sensitivity, specificity, positive and negative predictive values, and accuracy were first calculated independently for ea ch imaging technique. Finally, a second session resulted in a consensus dia gnosis being made based on the findings of all three modalities. Results. Sonographic evaluation of adnexal masses resulted in correct class ification of 11 of 12 ovarian malignancies (sensitivity 92%) but with a spe cificity of only 60%. With MRI and PET, specificities improved to 84 and 80 % respectively, but sensitivities decreased. When all imaging modalities we re combined, sensitivity and specificity were 92 and 85%, respectively, and accuracy was 86%. Conclusion. Combination of ultrasound with MRI and PET may improve accuracy in differentation of benign from malignant ovarian lesions. However, negat ive MRI or PET results do not rule out early-stage ovarian cancer or boderl ine malignancies. (C) 2000 Academic Press.