Breast MR imaging in assessing extent of disease.

Breast MR imaging is valuable in assessment of extent of disease in the ipsilateral and contralateral breast in women who have breast cancer. In the ipsilateral breast, MR imaging depicts otherwise unsuspected sites of cancer in 16% (range, 6%-34%). In the contralateral breast, MR imaging depicts otherwise unsuspected sites of cancer in 6% (range, 3%-24%). MR imaging is most likely to depict additional sites of cancer in women with invasive lobular cancer and a family history of breast cancer. MR imaging can also assist in evaluating involvement of skin, pectoral muscle, and chest wall. Disadvantages of breast MR imaging include cost and additional procedures (follow-up and biopsy); furthermore, no data as yet show that breast MR imaging in the extend of disease evaluation improves disease-free or overall survival. If breast MR imaging is used in evaluating extent of disease, it is necessary to have the capability to perform biopsy of lesions detected by MR imaging only.