In the study, investigators modified an MRI scanner to beam sound waves into the breast during MR imaging. A scanning technique developed by the Mayo researchers provides data which is then processed to yield images displaying the mechanical properties of breast tissues.
"Malignant breast tumors tend to be much harder than normal tissues and most benign tumors," says Richard Ehman, M.D., a Mayo Clinic diagnostic radiologist and principal investigator of the study. "This explains why breast cancer is often detected by physical examination simply on the basis of a very hard lump in the breast."
The MR elastography technique was tested on six healthy women and six women with known breast cancer. The images of women with breast cancer demonstrated areas of very high tissue stiffness corresponding to the known tumors. On average, the stiffness of the breast cancer tissue was more than four times higher than the surrounding tissue.
"Conventional MRI is very sensitive for detecting breast cancer, but unfortunately there are too many false positives," Dr. Ehman says. "The goal of our research is to determine whether we can use this new MR elastography technique to improve the accuracy of MRI for breast cancer diagnosis, thereby reducing the need for biopsies."
"Standard imaging techniques such as computed tomography, ultrasonography and MRI do not provide information about the mechanical properties of tissue," says Jennifer Kugel, Mayo Clinic research technologist and one of the authors of the study. "This new imaging technology is exciting because it allows us to look at tissues in a way that has never before been possible."
Breast cancer is the most commonly diagnosed life-threatening cancer in North American women. Mortality from this disease is stage-dependent, making early detection the key to survival. These considerations, along with the limitations of mammography, motivated Mayo Clinic researchers to develop this study.
"Mammography does not work as well for women with dense breasts, those who have had lumpectomies or premenopausal women," Kugel says. "In these cases, a combination of MRI and MR elastography could be used as an additional screening tool."
This research is supported by a grant from the National Cancer Institute.