In the management of breast neoplasms, two breast MR examinations are performed, one before initiation of neoadjuvant chemotherapy (NAC) and one at the end. However, a third MR exam may be performed between two courses of chemotherapy in order to assess tumor response to treatment. The assessment criterion currently used is measurement of tumor diameter according to RECIST (Response Evaluation Criteria In Solid Tumors) and WHO. But according to the preliminary results of the American College of Radiology Imaging Network protocol, using measurement of tumor volume as a reference may be valuable. Larger series are therefore necessary to estimate the value of diffusion MR, spectroscopy and diffusion studies.