MR imaging of the ipsilateral breast in women with percutaneously proven breast cancer.

OBJECTIVE. The purpose of this study was to review MR imaging findings in the ipsilateral breast in women with percutaneously proven breast cancer. MATERIALS AND METHODS. Retrospective review was performed of records of 70 consecutive women with percutaneously proven unilateral breast cancer who were considered candidates for breast conservation surgery and who had preoperative MR imaging of the ipsilateral breast. MR images and medical records were reviewed. RESULTS. MR imaging identified mammographically and clinically occult cancer other than the index lesion in the ipsilateral breast in 19 women (27%), including infiltrating cancer in 11 women (16%) and ductal carcinoma in situ in eight women (11%). These additional sites of cancer were in the same quadrant as the index cancer in 14 women (20%), in a different quadrant in three women (4%), and in both the same and different quadrants in two women (3%). Additional sites of cancer were more likely in women with, rather than in those without, a family history of breast cancer (42% vs 14%, p < 0.02) and in women whose index cancer was infiltrating lobular rather than other histologies (55% vs 22%, p < 0.06). In 17 women (24%), MR imaging detected ipsilateral lesions that were benign. Changes due to prior percutaneous biopsy were infrequently observed on MR images and included a clip in 12 women (17%) and a small hematoma in two women (3%). CONCLUSION. MR imaging identified additional sites of ipsilateral cancer in 27% of women with percutaneously proven breast cancer. The yield was highest in women with a family history of breast cancer or infiltrating lobular histology in the index cancer. Change after biopsy was infrequent and did not interfere with the MR imaging interpretation.