Mammograms and Other Breast Imaging Tests

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When are other breast imaging tests used?

While mammograms are the most useful tests for screening and finding breast cancer early, other imaging tests may be helpful in some cases.

MRI (magnetic resonance imaging)

MRI scans use magnets and radio waves instead of x-rays to produce very detailed, cross-sectional pictures of the body. The energy from the radio waves is absorbed and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. For breast MRI to look for cancer, a contrast liquid (called gadolinium) is injected into a vein before or during the scan to show details better.

Breast MRI is mainly used for 2 purposes:

  • For women who have been diagnosed with breast cancer, to help measure the size of the cancer and look for any other tumors in the breast. It also can be used to look at the opposite breast, to be sure that it doesn’t contain any tumors.
  • For certain women at high risk for breast cancer, screening MRI is recommended along with a yearly mammogram. MRI is not recommended as a screening tool by itself because it can miss some cancers that a mammogram would detect.

Just as mammograms are done with x-ray machines that are specially designed to image the breasts, breast MRI also requires special equipment. Not all MRI machines are set up to do breast MRIs.

It’s important that breast MRIs be done at facilities that also can do an MRI-guided breast biopsy. Otherwise, the entire scan will need to be repeated at another facility if a biopsy is needed.

MRIs cost more than mammograms. Most major insurance companies pay for these screening tests if a woman can be shown to be at high risk, but it’s a good idea to check with your insurance company before having the test.

When getting ready for a breast MRI, you can eat and drink as usual. You will need to take off clothes with metal parts such as zippers, snaps, or buttons, and put on a gown or top. Jewelry, hairpins, safety pins, and anything else made of metal must be removed before you go into the MRI room. The technologist will ask if you have any metal or devices in your body, such as surgical clips, staples, implanted catheters, pacemakers, defibrillators, artificial joints, metal fragments, tattoos, permanent eyeliner, and so on. Some metal objects will not cause problems, but others might. Tell the staff before the scan if you have any allergies, if you have breast implants, or if you are pregnant or breast-feeding.

You may need to have an IV put in so you can get contrast dye to help outline the structures of the breast. For the actual MRI, you will lie on your stomach on a padded platform with spaces for your breasts. You will need to be very still during the test, which can take up to an hour.

Breast ultrasound

Ultrasound, also known as sonography, uses sound waves to look inside a part of the body. A gel is put on the skin of the breast and a handheld instrument called a transducer is rubbed with gel and pressed against the skin. It emits sound waves and picks up the echoes as they bounce off body tissues. The echoes are converted by a computer into a black and white image on a computer screen. This test is painless and does not expose you to radiation.

Breast ultrasound is sometimes used to evaluate breast problems that are found during a screening or diagnostic mammogram or on physical exam. Breast ultrasound is not routinely used for screening. Some studies have suggested that it may be helpful to use ultrasound along with a mammogram when screening high risk women with dense breast tissue (which is hard to evaluate with a mammogram). But at this time, ultrasounds cannot replace mammograms. More studies are needed to figure out if ultrasound should be added to routine screening mammograms for some groups of women.

Ultrasound is useful for taking a closer look at some breast masses, and it’s the only way to tell if a mass is a cyst without putting a needle into it to take out (aspirate) fluid. Breast ultrasound may also be used to help doctors guide a biopsy needle into an area of concern in the breast.

There is a newer system, called a 3-dimensional automated whole breast ultrasound, which can be used on the breast. The FDA has approved it to be used along with mammography. The 3-D ultrasound can be done with a handheld transducer, but more often, a larger transducer is placed over the whole breast, which can then be scanned automatically.

Ultrasound has become a valuable tool to use along with mammograms because it’s widely available, non-invasive, and costs less than other options. But the value of an ultrasound test depends on the operator’s level of skill and experience—though this is less important with the new automated ultrasound systems. Ultrasounds aren’t used by themselves for screening because they can miss some cancers seen on mammograms. Ultrasound is less sensitive than MRI (that is, it detects fewer tumors), but it has the advantages of costing less and being more widely available.

Ductogram (galactogram)

A ductogram, also called a galactogram, is sometimes used to help find the cause of any worrisome nipple discharge. In this test, a very thin plastic tube is put into the opening of a duct in the nipple that the discharge is coming from. A small amount of contrast material is put in. It outlines the shape of the duct on x-ray and can show whether there is a mass inside the duct.


Last Medical Review: 12/10/2013
Last Revised: 12/10/2013