Breast MRI

MRI stands for magnetic resonance imaging. A physician will request an MRI to gain detailed images of organs and structures within the body in order to help diagnose a health problem.

By using a large magnet, an MRI machine creates a strong magnetic field around the patient. This magnetic field, along with radio waves, alter the natural alignment of hydrogen atoms in the body. The magnetic field lines up the hydrogen protons, and the radio waves knock the protons out of position. As the protons realign back into proper position, they send out radio signals. A computer uses these signals to form two-dimensional (2-D) images of the body structure or organ.

Cross-sectional views of the image also can be done with MRI to show more details.

The American Cancer Society (ACS) recommends MRI in conjunction with mammograms for women at very high risk for cancer. MRI is not to be used in place of mammograms for breast cancer screening.

According to the ACS, women who meet the following guidelines should have an MRI annually with their mammogram. Most plans cover this exam with at least one of the following criteria with pre-authorization:

• BRCA1 or BRCA2 mutation.
• First-degree relative (i.e., parent, sibling, child) with a BRCA1 or BRCA2 mutation, even if they have yet to be tested themselves.
• Lifetime risk of breast cancer has been scored at 20-25 percent or greater, based on one of several accepted risk assessment tools that look at family history and other factors.
• Received radiation treatment to the chest between ages 10-30.
• Has Li-Fraumeni syndrome, Cowden syndrome or Bannayan-Riley-Ruvalcaba syndrome, or may have one of these syndromes based on a history in a first-degree relative.

While an MRI is more sensitive than mammograms, it is also more likely to detect abnormalities in the breast that may or may not be cancer. Often, the only way to make a definitive diagnosis is through biopsy.

MRI results in more false positives than mammograms, which can lead to fear and anxiety for the patient, and many unnecessary biopsies. Thus, MRI is not recommended for women at average risk.