Test Overview
Magnetic resonance imaging (MRI)
uses a magnetic field
and pulses of radio waves to make pictures of the breast. 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.
See pictures
of a standard MRI machine and an
open MRI machine.
Why It Is Done
An MRI of the breast is done to:
- Find
breast cancer. Breast MRI may be done when a mammogram or breast ultrasound scan cannot tell if a lump is cancer.
- Check women who are at high risk for breast cancer. MRI may be recommended as a
screening tool for very high-risk women, such as those who test positive for
the BRCA1 or BRCA2 gene, or who have two or more close family members who have
had breast or ovarian cancer before age 50.
- Check women who have
dense breast tissue.
- Check the opposite breast. MRI is sometimes used to evaluate the
opposite breast in women diagnosed with certain types of
breast cancer.
- See what stage of breast cancer is present so the
best treatment can be chosen.
- Look at breast tissue changes during
treatment for breast cancer.
- Check breasts with inverted nipples for any sign of breast
cancer.
- Find a breast implant rupture. MRI of the breast is the
best test for this purpose.
- Look at a suspicious area of the breast
for women with breast implants.
How To Prepare
Tell your doctor and the MRI
technologist if you:
- Have a
pacemaker,
implantable cardioverter-defibrillator (ICD),
artificial limb, any metal parts in your body, tattooed eyeliner or
metallic-based tattoos, or any other implanted medical device, such as a
medicine infusion pump. Also, tell your doctor if you have worked around
metal or if you have recently had surgery on a blood vessel. In some cases you
may not be able to have the MRI test.
- Are or might be
pregnant.
- Become very nervous in confined spaces. You need to lie
very still inside the MRI scanner, so you may need to have the test done with
an open MRI machine that is not as confining as standard MRI machines, or you
may need medicine to help you relax.
- Have allergies, especially to
any medicines.
- Have
asthma.
- Wear any medicine patches. The MRI
may cause a burn at the patch site.
- Have other health problems, such as kidney problems or
sickle cell anemia. Contrast material cannot be used
with some health problems.
Arrange to have someone take you home after the test in
case you are given a medicine (sedative) to help you relax.
You may need to sign a consent form that says you understand the risks of
an MRI and agree to have the test 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?).
How It Is Done
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.
Before the test
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
During the test, you will lie on
your stomach or your back 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. Some MRI machines (called open MRI) are now
made so that the scanner does not enclose your whole body.
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.
How It Feels
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. Open MRI
machines are less confining than a standard MRI and may be helpful if you are
claustrophobic.
If dye is used, you may feel some coolness and
flushing as it is put into your vein.
In rare cases, you may
feel:
- A tingling sensation in your mouth if you have
metal dental fillings.
- Warmth in the breast. This is normal and
does not need treatment unless it becomes bothersome. Tell the technologist if
you:
- Have any breathing
problems.
- Feel sick to your stomach.
- Have a
headache.
- Feel dizzy.
- Have pain.
- Feel a
burning sensation.
- Have itchy skin.
Risks
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.
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.
Results
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.
Magnetic resonance imaging (MRI) of the breast
| 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.
|
| Abnormal: |
Solid masses are
present.
|
|
Signs of infection or inflammation are
present.
|
|
A breast implant is ruptured.
|
|
Underarm lymph nodes do not look
normal.
|
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Pregnancy. An MRI test usually is not done
during pregnancy. If you are pregnant, an ultrasound test may be done
instead.
- Medical devices that have metal, such as a
pacemaker or an
ICD. These devices may not function properly or can
cause problems during an MRI scan.
- Other types of metal, such as
surgical clips. If these will interfere with a breast MRI, the test will not be
done.
- Inability to remain still during the
test.
- Being very overweight. This may affect your ability to fit
into the opening of some standard MRI machines.
What To Think About
- Abnormal findings on a breast MRI often are not cancer. If the
MRI has an abnormal result, your doctor will do other testing to find out if
the problem is serious. This may involve doing an ultrasound test or a
biopsy, or both.
- Sometimes your MRI test
results may be different because you were tested at a different medical center
or earlier test results are not available to compare to the new test
findings.
- An MRI may be more likely to report a problem in the breast when
a problem is not there (false-positive) than other tests. A
false-positive result may lead to more tests when no serious problem is
present. For more information, see the topic
Breast Cancer (BRCA) Gene Test.
- While MRI
is a safe and valuable test for looking at your breast, it is much more costly
than other methods, and it may not be available in your area.
- Open
MRI machines are now made so that the magnet does not completely surround you.
Open MRI is useful for people who are claustrophobic or obese. But these
machines are not available everywhere. Also, these machines may not be able to
do all the studies needed to check for problems. Open MRI can be used to guide
treatments (interventional treatments) or procedures, such as a biopsy.
-
Contrast material
that contains gadolinium may cause a
serious problem (called nephrogenic systemic fibrosis) in people with
kidney failure. Tell your doctor if you have serious
kidney disease before having an MRI scan.
References
Other Works Consulted
- 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.
- Lehman CD, et al. (2007). MRI evaluation of the
contralateral breast in women with recently diagnosed breast cancer.
New England Journal of Medicine, 356(13):
1295–1303.
- 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.
- Saslow D, et al. (2007). American Cancer Society
guidelines for breast screening with MRI as an adjunct to mammography.
CA: A Cancer Journal for Clinicians, 57(2): 75–89.
Available online:
http://www.caonline.amcancersoc.org/cgi/content/full/57/2/75.
Credits
|
By
|
Healthwise Staff |
|
Primary Medical Reviewer
|
Kathleen Romito, MD - Family Medicine |
|
Specialist Medical Reviewer
|
Howard Schaff, MD - Diagnostic Radiology |
|
Last Revised
|
May 28, 2010 |