Definition of Breast MRI scan:

A breast MRI (magnetic resonance imaging) scan is a 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. However, it is not a replacement for mammography.

See also:

• Breast self-exam
• Breast ultrasound
• Mammography

How the test is performed:

You will lie on your stomach with your breasts hanging down into cushioned openings. The narrow table slides into the MRI scanner, which is shaped like a tunnel.

You may be asked to wear a hospital gown or clothing without metal fasteners (such as sweatpants and a t-shirt). Certain types of metal can cause blurry images.

Some exams require a special dye (contrast). The dye is usually given before the test through a vein (IV) in your hand or forearm. The dye helps the radiologist see certain areas more clearly.

During the MRI, the person who operates the machine will watch you from another room. The test most often lasts 30-60 minutes, but may take longer.

How to prepare for the test:

You may be asked not to eat or drink anything for 4 - 6 hours before the scan.

Tell your doctor if you are afraid of close spaces (have claustrophobia). You may be given a medicine to help you feel sleepy and less anxious, or your doctor may suggest an "open" MRI, in which the machine is not as close to the body.

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 contrast)
• Recently placed artificial joints
• Certain types of vascular stents
• Worked with sheet metal in the past (you may need tests to check for metal pieces in your eyes)

Because the MRI contains strong magnets, metal objects are not allowed into the room with the MRI scanner:

• Pens, pocketknives, and eyeglasses may fly across the room.
• Items such as jewelry, watches, credit cards, and hearing aids can be damaged.
• Pins, hairpins, metal zippers, and similar metallic items can distort the images.
• Removable dental work should be taken out just before the scan.

How the test will feel:

An MRI exam causes no pain. If you have difficulty lying still or are very nervous, you may be given a medicine to relax you. Too much movement can blur MRI images and cause errors.

The table may be hard or cold, but you can request a blanket or pillow. The machine produces loud thumping and humming noises when turned on. You can wear ear plugs to help reduce the noise.

An intercom in the room allows you to speak to someone at any time. Some MRIs have televisions and special headphones that you can use to help the time pass.

There is no recovery time, unless you were given a medicine to relax. After an MRI scan, you can resume your normal diet, activity, and medications.

Why the test is performed:

MRI provides detailed pictures of the breast. It also provides clear pictures of parts of the breast that are difficult to see clearly on ultrasound or mammogram.

Breast MRI may also be performed to:

• Check for more cancer in the same breast or the other breast after breast cancer has been diagnosed
• Distinguish between scar tissue and tumors in the breast
• Evaluate a breast lump (usually after biopsy)
• Evaluate an abnormal result on a mammogram or breast ultrasound
• Evaluate for possible rupture of breast implants
• Find any cancer that remains after surgery or chemotherapy
• Guide a biopsy (rare)
• Screen for cancer in women at very high risk for breast cancer (such as those with a strong family history)
• Screen for cancer in women with very dense breast tissue

An MRI of the breast can also show:

• Blood flow through the breast area
• Blood vessels in the breast area