Abstract： Objective To investigate the diagnostic value of breast MRI in patients presenting with microcalcifications on mammography.Methods Eight four patients were retrospectively analyzed,who had mammographically detected BI-RADS (breast imaging reporting and data system) 3 to 5 microcalcifications and underwent breast MRI before surgical biopsy.All mammography and MR images were reviewed with BI-RADS.With histopathological diagnosis as golden standard,the sensitivity,specificity and accuracy of the two methods were calculated and compared with x2 test or Fisher exact test.The diagnostic efficacy of the two methods was compared with ROC curve.Results Pathologic examination revealed 91 lesions in 84 patients including 49 benign lesions and 42 malignant lesions.For 21 lesions of category 3 microcalcifications,the specificity of mammography and MR was 100.0％ (21/21) and 95.2％ (20/21),which had no significant difference (P=1.000).For 51 lesious of category 4,sensitivity,specificity and accuracy of mammography were 100.0％(23/23),0 and 45.1％(23/51).The corresponding values for MR were 91.3％(21/23),82.1％ (23/28) and 86.3％ (44/51).The difference for specificity and accuracy between the two methods was statistical significant(x2 value was 30.030 and 19.182,respectively,with P＜0.01),but not for sensitivity(x2=0.523,P=0.470).Nineteen lesions of category 5 were all correctly diagnosed on mammography and MRI.For all the 91 lesions,the sensitivity,specificity and accuracy of mammography were 100.0％(42/42),42.9％(21/49) and 69.2％(63/91),respectively.The corresponding values for MRI were 95.2 ％(40/42),87.8％(43/49) and 91.2％(83/91).There was significant difference for specificity and accuracy between the two methods (x2 value was 21.798 and 13.851,respectively,with P＜0.05),but not for sensitivity (x2=0.512,P=0.474).The areas under ROC curve for mammography and MR were 0.844,0.945(P＜0.01),for the estimation of the benign and the malignent.Conclusions Compared with mammography,breast MRI significantly improved the diagnosis of category 4 microcalcifications with increased specificity and accuracy.But for microcalcifications of category 3 and 5,MR didn't improve the diagnostic effect.