The role of breast MRI in planning the surgical treatment of breast cancer.

PURPOSE To determine the frequency by which breast magnetic resonance imaging (MRI) provides information that influences the surgical management of patients with breast cancer. MATERIALS AND METHODS From August 2006 to December 2008, contrast-enhanced bilateral breast MRI was performed on 68 patients, all of whom exhibited highly suspicious imaging findings (BI-RADS category 4 or 5). Patients were grouped according to their histopathological diagnosis and type of breast parenchyma. All of the enrolled patients were believed to be candidates for breast conservation on the basis of physical examination, mammography, and ultrasonography. The patients were reevaluated with the MRI examination as to whether they were still candidates for breast conservation therapy. RESULTS The MRI findings changed the previous management plans in 19.1% of the 68 patients. With respect to the surgical approach, no statistically significant difference was observed between the histopathology groups (P = 0.403). In terms of the breast parenchymal pattern, however, surgical planning was changed in 53.8% of the patients who exhibited a dense pattern, which was significantly different from the rates of the other groups (P = 0.006). The sensitivity, specificity, positive predictive value, and negative predictive value of the MRI for additional malignant lesion detection and identification were 85%, 98%, 92%, and 96%, respectively. The agreement test revealed 86% agreement (very good) between the additional findings observed on the MRI and the histopathological results. CONCLUSION If breast-conserving surgery is planned, an MRI should be performed in all women with suspected breast cancer, especially those exhibiting dense or heterogeneously dense breast parenchyma, for which the sensitivity of both ultrasonography and mammography is low.