Staging of suspected breast cancer: effect of MR imaging and MR-guided biopsy.

PURPOSE: To investigate the effect of contrast material-enhanced magnetic resonance (MR) imaging on staging of breast cancer in patients with mammographically or clinically suspected tumor. MATERIALS AND METHODS: One hundred seventy-six patients underwent breast MR imaging at 1.5 T before excisional biopsy of a suspicious mammographic or palpable abnormality. Diagnostic imaging studies in patients with biopsy-proved or presumed breast carcinoma were reviewed. RESULTS: Sixty-four patients met the study criteria. MR imaging enabled detection of all 57 invasive breast cancers and nine of 15 in situ cancers. In 22 patients (34%), MR imaging depicted one or more cancers not visible at mammography, 13 (20%) of which were unsuspected multifocal or diffuse disease. As a result of the increased sensitivity of MR imaging compared with that of mammography, clinical staging and subsequent treatment were altered in seven patients (11%). CONCLUSION: MR imaging allows detection of mammographically and clinically occult foci of carcinoma in patients with suspected breast cancer.