This is one of the most important questions in the field of breast imaging today.
It is important to keep in mind that there are widely varied opinions about this question depending who you ask. As a breast imaging radiologist, my opinion may differ from physicians in other specialties. My opinion, however, is formed from all prior studies and current research, as well as personally interpreting hundreds of thousands of mammograms, tens of thousands of ultrasounds, thousands of breast MRI’s, and diagnosing hundreds of breast cancers each year.
I could spend significant time discussing the relative “reliability” of breast MRI in scientific terms of sensitivity (how likely breast MRI is to detect breast cancer when it is present) and specificity (how likely breast MRI is to be correct when it shows what looks like breast cancer), but I think the message would be lost, so I will do my best to answer the essence of this question based on my opinion in the simplest terms.
First, mammography saves lives. Independent studies in the United States and several countries throughout the world have demonstrated time and time again that annual screening with mammograms reduces the number of deaths from breast cancer anywhere from 20–48%. Recent studies have demonstrated that the newer 3-D technology is even better than the traditional 2-D mammogram in terms of detecting more cancers.
As a result, annual screening mammograms are generally recommended by the majority of major health organizations such as the American Cancer Society, The American College of Radiology and the Society of Breast Imaging, The National Cancer Comprehensive Network, the American Medical Association, and others. However, in addition to mammography, breast ultrasound and breast MRI are increasingly playing large roles in breast cancer screening.
Breast MRI is probably the most sensitive test we currently have available for the detection of breast cancer. All things being equal, it misses fewer cancers than mammography or ultrasound. While it is more common that a breast cancer cannot be seen on mammogram but shows up on breast MRI, it occasionally happens that a breast cancer cannot be seen on breast MRI which shows up on a mammogram. For this reason, breast MRI and mammogram are considered to be complementary tests.
It is currently recommended by the American Cancer Society, the American College of Radiology and other organizations that women with high risk for breast cancer undergo annual breast MRI in addition to annual mammogram. If you want more detailed information about breast MRI see this recent article I wrote for SW Florida Health and Wellness Magazine:
Recent research however, is demonstrating that breast MRI may even be useful for women at average lifetime risk of developing breast cancer. If you want more information about this research see this article from one of my earlier posts here:
Although breast MRI is extremely powerful, one of the criticisms is that it can occasionally be difficult to differentiate some forms of active but normal breast tissue (and other findings) from certain forms of breast cancer (usually low grade breast cancers). This becomes more of an issue when someone who does not have extensive experience reading breast MRI attempts to interpret a study, or when the facility performing the study, does not do a sufficient number of breast MRI’s to produce consistent or high quality images.
Breast ultrasound can also be a useful supplement to mammography, but is highly dependent on the ultrasound technologist and equipment and can be a worthless test in the wrong hands. It will undoubtedly miss more cancers than breast MRI, but occasionally demonstrates cancers that cannot be seen on mammogram. However, there are several forms of breast cancer which are not seen on ultrasound and therefore ultrasound should never be substituted for a mammogram.
I could go on and there are many other complex considerations to this question, but I feel these points are some of the most important considerations at the present time. With the amount of confusion there is out there regarding this question, I like to take the time and educate where I can. Hopefully, this has been helpful.
Ryan Polselli, M.D., Breast Imaging Radiologist
This answer is for general informational purposes only and is not a substitute for professional medical advice. Always seek the advice of your doctor before starting or changing treatment.