Magnetic resonance imaging (MRI) uses a magnetic field and pulses of radio waves to make pictures of the breast. It does not use X-rays. MRI may show problems in the breast that cannot be seen on a mammogram, ultrasound, or CT scan.
The MRI makes pictures that show your breast's normal structure; tissue damage or disease, such as infection; inflammation; or a lump. MRI is better than mammography or ultrasound for looking at some breast lumps.
In most cases, a dye (contrast material) may be used so that abnormalities can be seen more clearly from normal breast tissue. The contrast material makes it easier to find problems with increased or abnormal blood flow, such as with some types of cancer or areas of inflammation.
MRI is a safe and valuable test for looking at the breast, but it has a high rate of false-positive results, and it is more costly than other methods and is not available in all hospitals.
You may be able to have an MRI with an open machine that doesn't enclose your entire body. But open MRI machines aren't available everywhere. The pictures from an open MRI may not be as good as those from a standard MRI machine.
An MRI of the breast is done to:
Women at increased risk for breast cancer may have screening tests that alternate between MRIs and mammograms. This is done because the tests can detect different kinds of problems.
Before your MRI test, tell your doctor and the MRI technologist if you:
Arrange to have someone take you home after the test in case you are given a medicine (sedative) to help you relax.
You may be asked to sign a consent form that says you understand the risks of the test and agree to have it done.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).
An MRI of the breast is usually done by an MRI technologist. A radiologist usually studies the pictures to look for problems. But some other types of doctors may also do this.
You will need to remove all metal objects (such as hearing aids, dentures, jewelry, watches, and hairpins) from your body because these objects may be attracted to the powerful magnet used for the test. If there is a possibility that you have metal fragments in your eyes from an accident or a surgery or because you work around metal, an X-ray or a CT scan will be done before the MRI to see if any metal is present. An X-ray or CT may also be done if there is a concern about metal fragments in your head or spine.
You will need to take off your clothes above the waist. You will be given a gown to cover your shoulders during the test. Empty your pockets of any coins and cards (such as credit cards or ATM cards) with scanner strips on them because the MRI magnet may erase the information on the cards.
During the test, you will lie on your stomach on a table that is part of the MRI scanner. Straps may be used to help keep your body in the best position. The table will slide into the machine part that holds the magnet. A device called a coil may be placed over or wrapped around the breast area.
Inside the scanner, you will hear a fan and feel air moving. You may also hear tapping or thumping noises as the MRI scans are taken. You may be given earplugs or headphones with music to lessen the noise. It is very important to hold completely still while the scan is being done. Otherwise, repeat scans may be needed. Also, you may be asked to hold your breath for short periods of time.
During the test, you may be alone in the scanner room. But the technologist will watch you through a window, and you will be able to talk to him or her through a speaker.
If contrast material is needed, the technologist will put it in a vein (intravenous, or IV) in your arm. The contrast material may be given over 1 to 2 minutes. Then more MRI scans are taken.
An MRI test usually takes 30 to 60 minutes but may last as long as 2 hours.
You will not have pain from the magnetic field or radio waves. The table you lie on may feel hard and the room may be cool. You may become uncomfortable from lying in one position for a long time.
Some people feel anxious (claustrophobic) inside the MRI machine. You may be given medicine (sedative) to help you relax.
If dye is used, you may feel some coolness and flushing as it is put into your vein.
In rare cases, you may feel:
There are no known harmful effects from the strong magnetic field used for MRI. But the magnet is very powerful. The magnet may affect pacemakers, implantable cardioverter-defibrillators (ICDs), artificial limbs, and other medical devices that contain iron.
If you may have metal fragments in your eyes, an MRI can cause damage to the retina. If there is a concern about metal fragments in the eye, most MRI clinics will do X-rays of the eyes before the MRI. If metal is found on the X-ray, the MRI will not be done.
Iron pigments in tattoos or tattooed eyeliner can cause skin or eye irritation problems.
An MRI can cause a burn with some medicine patches. Be sure to tell your doctor if you are wearing a patch.
Contrast material that contains gadolinium may cause a serious problem (called nephrogenic systemic fibrosis) in people who have kidney failure.
There is a small risk of having an allergic reaction if contrast material is used during the MRI scan. Most reactions are mild and can be treated with medicine. There is also a small risk of infection at the IV site.
An MRI may be more likely than other tests to report a problem in the breast when a problem is not there (false-positive). A false-positive result may lead to more tests such as a biopsy when no serious problem is really present. So MRI is not used as a screening test for women at low or average risk for breast cancer.
Magnetic resonance imaging (MRI) uses a magnetic field and pulses of radio waves to make pictures of the breast.
The radiologist may discuss the results of the MRI with you right after the test. Complete results are usually available to your doctor in 1 to 2 days.
An MRI scan can sometimes find a problem in a breast, even when the size and shape of the breast looks normal.
The breast tissue looks normal in size, shape, and appearance.
No solid masses are present.
A breast implant is intact.
No signs of inflammation or infection are present.
Solid masses are present.
Signs of infection or inflammation are present.
A breast implant is ruptured.
Underarm lymph nodes do not look normal.
Reasons you may not be able to have the test or why the results may not be helpful include:
Other Works Consulted
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Kuhl C (2007). The current status of breast MR imaging, part 2: Clinical applications. Radiology, 244(3): 672–691.
- Kuhl C (2007). The current status of breast MR imaging, part I. Choice of technique, image interpretation, diagnostic accuracy, and transfer to clinical practice. Radiology, 244(2): 356–378.
- Morrow M, et al. (2011). MRI for breast cancer screening, diagnosis, and treatment. Lancet 378(9805): 1804–1811.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
- Roth SO (2010). Imaging analysis: Magnetic resonance imaging. In JR Harris et al., eds., Diseases of the Breast, 4th ed., pp. 152–170. Philadelphia: Lippincott Williams and Wilkins.
|Primary Medical Reviewer||Sarah Marshall, MD - Family Medicine|
|Specialist Medical Reviewer||Howard Schaff, MD - Diagnostic Radiology|
|Last Revised||March 8, 2012|
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