A breast MRI (magnetic resonance imaging) scan is an imaging test that uses powerful magnets and radio waves to create pictures of the breast and surrounding tissue. It does not use radiation (x-rays).
A breast MRI may be done in combination with mammography or ultrasound. It is not a replacement for mammography.
MRI - breast; Magnetic resonance imaging - breast
How the Test is Performed
You will wear a hospital gown or clothes without metal snaps or zipper (sweatpants and a t-shirt). Some types of metal can cause blurry images.
You will lie on your stomach on a narrow table with your breasts hanging down into cushioned openings. The table slides into a large tunnel-like tube.
Some exams require a special dye (contrast). Most of the time, you will get the dye through a vein (IV) in your hand or forearm. The dye helps the docotr (radiologist) see some areas more clearly.
During the MRI, the person who operates the machine will watch you from another room. The test lasts 30 to 60 minutes, but may take longer.
How to Prepare for the Test
You may be asked not to eat or drink anything for 4 to 6 hours before the scan.
Tell your doctor if you are afraid of tight spaces (have claustrophobia). You may be given a medicine to help you feel sleepy and less anxious. Also, your doctor may suggest an "open" MRI. The machine is not as close to the body in this type of test.
Before the test, tell your health care provider if you have:
Brain aneurysm clips
Certain types of artificial heart valves
Heart defibrillator or pacemaker
Inner ear (cochlear) implants
Kidney disease or dialysis (you may not be able to receive the IV contrast)
Consult your provider with any questions and concerns.
MRI contains no radiation. No side effects from the magnetic fields and radio waves have been reported.
The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions to this dye are rare. However, gadolinium can be harmful to people with kidney problems that need dialysis. If you have kidney problems, tell your provider before the test.
The strong magnetic fields created during an MRI can make heart pacemakers and other implants not work as well. It can also cause a piece of metal inside your body to move or shift.
Breast MRI is more sensitive than mammogram, especially when it is performed using contrast dye. However, breast MRI may not always be able to distinguish breast cancer from noncancerous breast growths. This can lead to a false positive result.
MRI also cannot pick up tiny pieces of calcium (microcalcifications), which mammogram can detect.
A biopsy is needed to confirm the results of a breast MRI.
American Cancer Society recommendations for early breast cancer detection in women without breast symptoms. Last Revised: September 10, 2014. Available at: www.cancer.org/cancer/breastcancer/moreinformation/breastcancerearlydetection/breast-cancer-early-detection-acs-recs. Accessed: January 27, 2015.
American College of Obstetricians - Gynecologists. Practice Bulletin no. 122: Breast cancer screening. Obstet Gynecol. 2011;118:372-82. PMID 21775869. Available at: www.ncbi.nlm.nih.gov/pubmed/21775869.
American College of Radiology. ACR practice parameter for the performance of contrast-enhanced magnetic resonance imaging (MRI) or the breast. Updated 2014. Available at: www.acr.org/~/media/2a0eb28eb59041e2825179afb72ef624.pdf. Accessed January 27, 2015.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Breast cancer. Version 3. 2014. Available at: www.nccn.org/professionals/physician_gls/pdf/breast.pdf. Accessed: January 27, 2015.
Saslow D, Boetes C, Burke W, et al. American Cancer Society guidelines for breast screening with MRI as an adjunct to mammography. CA Cancer J Clin. 2007;57:75-89. PMID 17392385. Available at: www.ncbi.nlm.nih.gov/pubmed/17392385.
Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.