Central washout sign in computer-aided evaluation of breast MRI: Preliminary results

Background: Although computer-aided evaluation (CAE) programs were introduced to help differentiate benign tumors from malignant ones, the set of CAE-measured parameters that best predict malignancy have not yet been established. Purpose: To assess the value of the central washout sign on CAE color overlay images of breast MRI. Material and Methods: We evaluated the frequency of the central washout sign using CAE. The central washout sign was determined so that thin, rim-like, persistent kinetics were seen in the periphery of the tumor. Then, sequentially, plateau and washout kinetics appeared. Two additional CAE-delayed kinetic variables were compared with the central washout sign for assessment of diagnostic utility: the predominant enhancement type (washout, plateau, or persistent) and the most suspicious enhancement type (any washout > any plateau > any persistent kinetics). Results: One hundred and forty-nine pathologically proven breast lesions (130 malignant, 19 benign) were evaluated. A central washout sign was associated with 87% of malignant lesions but only 11% of benign lesions. Significant differences were found when delayed-phase kinetics were categorized by the most suspicious enhancement type (P<0.001) and the presence of the central washout sign (P<0.001). Under the criteria of the most suspicious kinetics, 68% of benign lesions were assigned as plateau or washout pattern. Conclusion: The central washout sign is a reliable indicator of malignancy on CAE color overlay images of breast MRI.