Objective To evaluate the ability of residual tumor shrinkage pattern by MRI after neoadjuvant chemotherapy(NCT) for breast cancer. Methods MRI and whole subserial section(WSS) of 48 patients with clinical TNM stage Ⅱ and stage Ⅲ infiltrating duct carcinoma were compared.All of 48 patients achieved four courses of neoadjuvant chemotherapy with Taxol and Epirubicin(TE)

and then examined by MRI.All of 48 patients received modified radical mastectomy after NCT

and the samples were subjected to perform WSS.Pathological changes of tumor bed and pericancerous tissues were examined with optical microscope. Results The shrinkage patterns were divided into two types

concentric shrinkage(CS) and dendritic shrinkage(DS).According to shrinkage pattern assessed by MRI

a total of 39(81.25%) patients showed CS after NCT

while

9(18.75%) patients showed DS.The WSS shrinkage pattern was CS in 40(83.33%) patients after NCT

and DS in 8(16.67%) patients.The correlation coefficient between the tumor shrinkage patterns assessed by MRI and that determined by pathological WSS after NCT was 0.906(P=7.37×10-8). Conclusion MRI can correctly evaluate the shrinkage pattern of residual tumor and provide important basis for clinical operation.