Early detection of ovarian cancer remains crucial for improving patient survival rates. However, early-stage disease is often asymptomatic, and population screening is currently unproven. Adnexal masses may be incidentally detected, but most are identified at ultrasonography (US) in patients who are symptomatic, and most may be characterized as benign or malignant. Indices are available to estimate the risk of malignancy on the basis of clinical and US findings. However, adnexal masses remain indeterminate in some cases, with some benign lesions demonstrating features of malignancy at US. In these cases, use of magnetic resonance (MR) imaging improves the ability to characterize adnexal masses and reduces the number of indeterminate lesions. Establishing the likelihood of malignancy on the basis of imaging features is important to the preoperative detection of early ovarian cancer and profoundly influences referral and management pathways. Conventional and contrast material-enhanced MR imaging are used to evaluate morphologic features, including lesion complexity, signal intensity, and enhancement of solid areas. At dynamic contrast-enhanced MR imaging with semiquantitative analysis, early enhancement characteristics may help differentiate some complex benign and malignant lesions. Diffusion-weighted imaging has a limited but useful role in evaluating adnexal masses: Those with a hypointense solid area on both diffusion-weighted (b = 1000 sec/mm²) and T2-weighted images are likely benign, whereas those that are hyperintense on diffusion-weighted images (b = 1000 sec/mm²) with intermediate signal intensity on T2-weighted images are likely malignant.
© RSNA, 2012.