Definition A mammogram is a type of X-ray for the breasts. A screening mammogram usually involves two X-rays of each breast. A diagnostic mammogram involves more X-rays.
Who is a candidate for the test? A screening mammogram is generally used to detect breast cancer or other changes in the breast tissue in women who do not have symptoms.
A diagnostic mammogram may be ordered when a screening mammogram shows something abnormal in the breast. It may also be ordered if the woman has symptoms, such as the following:
a discharge from the nipple other than breast milk
a lump or swelling in the breast or underarm area
redness or scaliness of the nipple or breast skin
retraction, or turning inward, of the nipple
skin irritation or dimpling
Breast cancer screening with mammograms has reduced deaths from breast cancer in women 40 to 69 years of age.
How is the test performed? For a screening mammography, the woman undresses to the waist and puts on a gown that opens from the front. The technologist places one breast on an X-ray film cassette, which resembles a metal shelf. The woman rests her breast on the film cassette. Usually the woman stands during this procedure.
A plastic paddle briefly squeezes the breast from above to flatten it out. This allows a clearer X-ray to be taken. Two views are usually taken of each breast for a screening mammogram. A diagnostic mammogram requires more views and more detail than the screening examination. With modern mammography equipment used specifically for breast X-rays, very low levels of radiation are used.
New techniques are being studied in a search for better diagnosis of breast abnormalities. Examples of these new techniques include the following:
digital mammography, which records images in computer code instead of on X-ray film
MRI imaging, which uses a large magnet and radio frequencies to produce pictures of the breast tissue
positron emission tomography, or PET, which uses radioactive materials to create computer images
radionuclides, which uses contrast agents
ultrasound, which uses ultrasound waves instead of X-rays
What is involved in preparation for the test? It is recommended that a mammogram be scheduled one week after a woman's last period. Women should not wear powder, deodourant, lotion, or perfume under the arms or on the breasts. Wearing a two-piece outfit is suggested. Prior to the examination, all jewellery and metal objects need to be removed.
What do the test results mean? A mammogram can detect breast cancer, often before a lump can be felt. A mammogram may also show the following conditions:
calcifications, or mineral deposits
cysts, or fluid-filled masses
leaking breast implants
noncancerous tumours or growths
Author: James Compton, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 6/06/2005 Contributors Potential conflict of interest information for reviewers available on request
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