We propose that the role of preoperative staging-MRI in breast cancer be studied by following the occurrence of negative margins at first surgery and the volume of resection in a randomized prospective study. The need for re-excision is an objective marker of satisfactory local surgery and is available as soon as the final pathology report is back. We propose that the closest margin and the rate of re-excision be used as the primary outcome measures to evaluate the contribution of MRI. In addition, since cosmetic preservation is one of the goals of breast conservation, we propose that cosmetic outcome be used as the secondary outcome measure. The visual analogue scale for cosmetic outcome varies between observers and with time; however, the volume of tissue that is excised is an objective surrogate of cosmetic outcome.15 Since the excised volume is dictated by the tumor volume, the only variable under the surgeon's control is the volume of benign tissue excised in order to obtain negative margins. Hence, in this study, we propose to use a volume index of excised margins as an outcome measure for cosmesis. The index value will be calculated for each subject by adding the two measurements of benign margin for each of the three dimensions measured and multiplying them to produce a volume index for each subject.