Role of MR Imaging for the Locoregional Staging of Breast Cancer.

Breast MR imaging has been shown to identify unsuspected sites of cancer in the ipsilateral breast in 16% of women with newly diagnosed breast cancer. Breast MR imaging identifies occult cancer in the contralateral breast in 3% to 5% of women. Early evidence suggests that the added value of MR imaging for staging may be attenuated in women who also undergo tomosynthesis, particularly those with nondense breasts. Breast MR imaging is complementary to ultrasound imaging in evaluating regional nodal basins. Ongoing prospective randomized clinical trials should clarify the impact of preoperative breast MR imaging on clinical outcomes.