Magnetic resonance imaging of the breast: potential for lesion characterization

To study the diagnostic performance of conventional mammography and dynamic contrast-enhanced magnetic resonance mammography (MRM) with regard to the detection of breast malignancy and recognition of a multifocal cancer, in particular in a dense breast.

Patients with abnormal breast findings (n=93; 30 malignant and 63 benign) were examined by mammography, sonography and MRM. In all patients, high-quality two-view mammography and 7.5 MHz sonography of both breasts were performed before MRM. Images were acquired on 1.5T scanner system. All lesions had been histologically confirmed.

The highest detection rate for multifocal invasive disease was seen with MRM, which identified 21 (72.5%) out of 29 histologically confirmed multifocal invasive cancers, whereas mammography identified 6 (20.5%) out of 24 (p=0.003). Lymph node metastases were present in 11 (37%) of 30 patients with malignant invasive carcinoma. MRM showed a sensitivity of 94.6%, specificity 78.5%, and accuracy 79.5%.

Compared with triple assessment for clinically overt and occult breast disease, MRM offers higher sensitivity for the detection of multifocal cancer, which is important in selecting patients appropriate for breast-conserving surgery. In conclusion, the multiplanar capability of MRM enables it to provide more definite information than mammography and ultrasonography. MRM is presently able to better stage breast cancer locally and to measure more accurately breast cancer size, and determine multicentricity.