Occult contralateral breast carcinoma incidentally detected by breast magnetic resonance imaging.

The incidence of synchronous bilateral breast cancers has been reported to be between 3.4% and 7.4%, as detected on mammography, physical examination, or both. We undertook a study to determine how often magnetic resonance (MR) imaging detects a contralateral abnormality in patients with known breast carcinoma. As part of an institutional review board (IRB) -approved research protocol, 17 patients with pathologically proven invasive carcinoma underwent preoperative MR imaging of both breasts using a T1-weighted, high-resolution gradient echo sequence (precontrast and postcontrast), an echo-planar sequence during administration of gadolinium, and a T2-weighted, fast-spin echo sequence. The morphology and dynamic enhancement of lesions in both breasts were assessed. Biopsy was recommended for any lesion meeting set criteria. MR imaging identified all 17 known invasive cancers in the breast of concern on mammography or physical examination. Five of 17 patients (29%) had 10 contralateral lesions identified on MR, for which biopsy was recommended. One of these lesions proved to represent a fibroadenoma. The other 9 lesions proved to represent a malignancy (6 invasive lobular, 2 infiltrating ductal, and 1 tubular). Four of the 17 patients (24%) with invasive cancer had contralateral synchronous cancers occult to physical examination, mammography, and ultrasonography. In this series, breast MR imaging of the breasts was more sensitive than mammography or physical examination in the detection of early breast cancer. Breast MR imaging of the contralateral breast may be of value as a routine screen in those patients with a known or suspected malignancy.