Magnetic resonance imaging: value of diffusion-weighted imaging in differentiating benign from malignant breast...

Although magnetic resonance imaging (MRI) has a high sensitivity in the detection of tumours, there is still much discussion about its role in breast cancer detection. MRI is not yet routinely used to further characterize lesions in patients diagnosed with breast cancer. This study investigated the impact of preoperative MRI on the surgical treatment of women with biopsy proven breast cancer. The diagnostic value of preoperative MRI was compared with that of conventional imaging (mammography and ultrasonography), and the diffusion-weighted imaging technique was also evaluated.

40 women underwent conventional imaging and biopsy as part of the clinical workup. In addition, preoperative MRI was performed in each patient. The kinetics of contrast captation were monitored and apparent diffusion coefficients were calculated. All imaging findings were compared with the histopathologic results, which were used as the gold standard. Differences in tumour extent, as determined by ultrasonography, MRI and histopathology, were evaluated.

Contrast captation kinetics curves are mostly aspecific, while apparent diffusion coefficient values seem to correlate much better with tumour malignancy. MRI correlated more accurately with histopathological findings than ultrasonography and even revealed unsuspected multifocal and multicentric breast carcinoma in 20 patients (50%). The surgical plan of seven patients (18%) was changed as a result of the additional information provided by MRI.

Diffusion-weighted imaging as a complementary tool to contrast captation kinetics and morphologic measurements may increase the specificity of MRI and help in differentiating between benign and malignant breast lesions. In addition, MRI yields more precise information than mammography and ultrasonography about the exact location, the extent, the multifocality or multicentricity of the tumour and can also detect possible additional tumours. Although MRI will never replace mammography (screening) or ultrasonography as a test for breast cancer in women with no high risk (e.g. BRCA 1 or 2 carriers), its use in a preoperative setting may allow more accurate staging of the disease, which in turn could result in a change in the treatment planning.