The purpose of this study was to evaluate the usefulness of preoperative breast MRI compared with breast US and pathologic finding in breast cancer patients

A total of 50 patients with breast cancer underwent surgery at our institute between October 2004 and August 2005. They were examined preoperatively with MRI and US. The maximum diameter and the number of the lesions on MRI and US were measured. These measurements were subsequently compared with the pathologic results. The results were divided into the equal, overestimated and underestimated groups. Changes of the therapeutic approach, based on MRI, were also evaluated.

Breast cancer was correctly evaluated in 38 of 50 (76%) patients with MRI and in 28 of 50 (56%) patients with US; the cancer was overestimated in 7 of 50 (14%) patients with MRI and in 8 of 50 (16%) patients with US; the cancer was underestimated in 5 of 50 (10%) patients with MRI and in 14 of 50 (28%) patients with US. The therapeutic approach was changed in 11 of 50 (22%) patients, and all the cases underwent modified radical mastectomy. The therapeutic approach was correctly changed in 9 (18%) patients. Unnecessary wider excision was performed in 2 (4%) patients.

In conclusion, preoperative breast MRI may be a useful modality for preoperative evaluation, especially for the local staging of tumor and the treatment planning of patients with breast cancer.