Magnetic resonance imaging: the evolution of breast imaging

To provide an overview of the principle of current breast MRI, the available evidence concerning its indications and optimum use and future potentials.

To date sensitivities of 90-91% have been achieved with a specificity of 72-75%. MRI is the most sensitive method for detecting invasive carcinoma and comparable to mammography concerning detection of DCIS. The achievable specificity, false positive and biopsy rates, however, are much lower than for screening mammography thus do not allow its use for screening of the general population. Indications with proven advantages concern screening of women at high risk and special diagnostic problems that cannot be solved by conventional imaging and percutaneous biopsy: search for primary tumour in CUP syndrome, differentiation of nipple retraction, differentiation of scarring versus recurrence and selected difficult cases. There is no proven benefit for its general use for preoperative staging. One major problem may concern the imperfect interface between imaging and surgery. Further research is also needed for the use of MRI in women at intermediate risk. In women at low risk MRI screening is not recommended. Novel possibilities of MRI concern diffusion weighted imaging as well as MR spectroscopy. Their value for improved lesion differentiation is not yet fully established. Their main potential appears to concern an improved and earlier prediction of response to neoadjuvant therapy. Future developments might address development of more specific contrast agents, replacement of vascular enhancing agents by special MR techniques, testing of sodium MRI or image fusion with other imaging modalities.

MRI allows new patho-physiological information and thus can complement the information available by conventional methods. Present research should concentrate on improving specificity, improving the interface of imaging and surgery and has to include outcome analyses. Due to issues of specificity the responsible use of MRI should be limited to appropriate indications.