PERIPHERAL WASHOUT SIGN ON CONTRAST-ENHANCED MR-IMAGES OF THE BREAST

PURPOSE: To assess the value of the peripheral washout sign on delayed contrast material-enhanced magnetic resonance (MR) images in differen tiation of benign from malignant breast masses. MATERIALS AND METHODS: In 49 women with 79 breast lesions (55 malignant and 24 benign), dyna mic contrast-enhanced MR imaging was performed every 90 seconds during the first 7 minutes and repeated at 10, 20, 30, 40, 50, and 60 minute s after injection of contrast material. Qualitative analysis of the im ages was performed to evaluate the presence of the peripheral washout sign (a hypointense zone in the periphery of the lesion relative to th e center). Quantitative analysis of the images was performed by measur ing the signal intensity of the periphery and center of the lesions. R ESULTS: The peripheral washout sign was seen in 28 (51%) of the 55 car cinomas on delayed contrast-enhanced MR images (>10 minutes). Quantita tive analysis demonstrated different enhancement profiles of the perip hery and center of these lesions. The periphery showed early increase and decrease of enhancement, while the center showed gradual increase and persistent enhancement. The peripheral washout sign was not seen i n any of the benign lesions. Specificity was 100% and sensitivity was 51% for diagnosis of breast carcinoma. CONCLUSION: Peripheral washout may be a reliable sign of malignancy on delayed contrast-enhanced MR i mages of the breast.