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.