This is a retrospective study based on the MR Mammography (MRM) case review from 1994 to 2003, together 1010 patients with 1129 lesions were included and all these patients were confirmed by histology. The results of this study show that: Edema sign is a reliable MR sign in the routine T2-weighted TSE images; Edema signs are more associated with the malignant lesions; And there is a correlation between the incidence of edema signs and tumor grading in the invasive carcinomas. Tumor-associated inflammation and angiogenesis in the stroma may be the pathophysiologic mechanism behind the edema signs and the correlation between edema signs and tumor grading. This study also shows that the surrounding changes detected by T2-weighted, like edema sign, might be a useful adjunct in predicting tumor prognosis. T2-weighted pulse sequences should be included in the routine protocol of MRM.