Abstract：Objective: To retrospectively estimate the diagnostic accuracy of diffusion-weighted MR imaging(DWI) in complex solid and cystic adnexal masses, and to determinate the optimal cutoff value for differentiating benign and malignant ovarian tumors. Materials and Methods: Eighty-four patients underwent DWI. The adnexal lesions were examined for several features including size, shape, character(solid-cystic), signal intensity, and enhancement. The mean ADC value of the solid components was measured and assessed for each ovarian mass. Receiver operating characteristic(ROC) was used to assess ability of ADC in differentiating benign versus malignant complex adnexal masses. Results: The mean ADC value was (1.456±0.297)×10-3 mm2/s and (0.929±0.215)×10-3 mm2/s for the benign and malignant masses respectively, and there was significant difference between them(P﹤0.01). The ROC results suggested that an ADC value ≥1.225×10-3 mm2/s might be an optimal cutoff value for differentiating benign and malignant tumors, with sensitivity of 86.7%, specificity of 94% and AUC of 92.1%，respectively. Conclusion: DWI is a useful supplement to conventional MRI. The measurement of ADC values of the solid components is especially useful for differentiating benign from malignant ovarian masses.
2012, Vol. 23 
