- What are imaging tests?
- Who does imaging tests and who interprets them?
- Types of imaging tests
- Computed tomography (CT) scan
- Magnetic resonance imaging (MRI)
- X-rays and other radiographic tests
- Nuclear medicine scans
- Categories of some common imaging tests
- Questions about radiation risk from imaging tests
- Factors that determine which imaging tests are used in different types of cancer
- To learn more
Other names include mammogram and digital mammography.
What does it show?
A mammogram is an x-ray of the breast. A screening mammogram is used to look for signs of breast cancer when you do not have any breast symptoms or problems. A mammogram can often detect cancer in its early stages, even before a lump can be felt, when treatment can be most successful. Screening mammograms usually take x-ray pictures of each breast from 2 different angles.
Mammograms can also be used to look at a woman’s breast if she has a breast problem or a change seen on a screening mammogram. When used in this way, they are called diagnostic mammograms. They may include extra views (images) of the breast that are not usually done on screening mammograms.
Mammograms can’t prove that an abnormal area is cancer, but they can give information that shows whether more testing is needed. The 2 main types of breast changes found with a mammogram are calcifications and masses.
Calcifications are tiny mineral deposits within the breast tissue, which look like small white spots on the pictures. They may or may not be caused by cancer.
A mass, which may or may not have calcifications, is another important change seen on mammograms. Masses can be many things, including cysts (fluid-filled sacs) and non-cancerous solid tumors, but they could also be cancer. Any mass that’s not clearly a simple fluid-filled cyst usually needs to be biopsied. (A biopsy is taking out a piece of tissue to see if cancer cells are in it.)
Having your older mammograms available for the radiologist is very important. They can help to show if a mass or calcification has changed over time, which could affect whether a biopsy is needed.
How does it work?
A mammogram uses a machine designed to look only at breast tissue. The machine takes an x-ray at lower doses than a usual x-ray. Because these x-rays do not go through tissue easily, the machine has 2 plates that compress or flatten the breast to spread the tissue apart. This gives a better picture and uses less radiation.
A digital mammogram (also known as full-field digital mammography or FFDM) is like a standard mammogram in that x-rays are used to make a picture of the breast. The differences are in the way the picture is made, looked at, and stored. Standard mammograms are printed on large sheets of photographic film. Digital images are recorded and saved as files in a computer. After the exam, the doctor can look at the pictures on a computer screen and adjust the size, brightness, or contrast to see certain areas more clearly. Digital images can also be sent electronically to another site for other breast specialists to see.
Digital mammograms are becoming more widely available. They may be better than standard (film) mammograms for some women, but they are not clearly better for everyone. Women should not skip their regular mammogram because a digital mammogram is not available.
How do I get ready for the test?
If you are still having periods, the best time to schedule a mammogram is one week after your period, when your breasts are likely to be less tender.
You’ll need to undress from the waist up for the exam, so you might want to wear a shirt and a skirt or pants, rather than a dress. No special preparation is needed. But on the day of your mammogram, do not use deodorants, perfumes, powders, or ointments under your arms or on your breasts because these may interfere with the pictures.
What is it like having the test?
A mammogram is an outpatient test. You will be asked to undress from the waist up and may need to remove any jewelry around your neck. You will stand next to the mammogram machine, which will be adjusted to your height. A specially qualified radiology technologist will position your breast on a platform. The technologist will use the machine to slowly compress your breast with an adjustable plastic plate. The compression will be tight and uncomfortable, but it doesn’t last very long. You hold your breath while the technologist leaves the room and quickly takes the picture. Then the pressure is released right away.
A screening mammogram usually means 2 views of each breast—one from the top and one from the side. You may need to have more pictures taken to include as much breast tissue as possible if you have breast implants. You also will have more pictures taken if the mammogram is being used for diagnosis (a diagnostic mammogram) or to guide the placement of a needle for a biopsy.
How long does it take?
The screening mammogram from start to finish takes about 15 to 30 minutes. A diagnostic mammogram, which takes images from more angles or close-up views, takes about 30 to 45 minutes. Each breast is compressed for only a few seconds of that time.
What are the possible complications?
A mammogram uses low doses of radiation and is safe. The very low risk that cancer may result from exposure to radiation during a mammogram is far outweighed by the benefits of finding cancer early.
Some women find that mammograms are painful, but for most the compression causes only brief discomfort.
There have been reports of breast implant ruptures during mammograms, but these are very rare. If you have breast implants, be sure to let the facility know about this ahead of time and find a radiologist experienced in doing mammograms on women with implants.
What else should I know about this test?
- The American Cancer Society has guidelines for the early detection of breast cancer in women who are not having breast symptoms. You can learn more in Breast Cancer: Early Detection.
- Mammograms alone cannot find all breast cancers. Knowing how your breasts normally look and feel, and reporting any changes to a doctor, is also very important.
- A negative mammogram (no sign of calcifications or masses) does not always mean that cancer is not present or that cancer will not develop later.
- The need for a biopsy does not mean that you have cancer. In fact, fewer than 1 out of 10 women who are called back for more tests turn out to have cancer.
For more details on mammograms and other tests related to breast cancer, see Mammograms and Other Breast Imaging Tests.
Last Medical Review: 03/16/2015
Last Revised: 09/15/2015