Mammography is a specific type of imaging that uses a low-dose x-ray system to examine breasts. A mammography exam, called a mammogram, is used to aid in the early detection and diagnosis of breast diseases in women. Mammograms are used as a screening tool to detect early breast cancer in women experiencing no symptoms and to detect and diagnose breast disease in women experiencing symptoms such as a lump, pain or nipple discharge.
Digital (computerized) mammography is similar to standard mammography in that x-rays are used to produce detailed images of the breast. Digital mammography uses essentially the same mammography system as conventional mammography, but the system is equipped with a digital receptor and a computer instead of a film cassette. This results in shorter examination times and significantly improved patient comfort and convenience since the time the patient must remain still is much shorter.
In standard mammography, images are recorded on film using an x-ray cassette. The film is viewed by the radiologist using a “light box”. With digital mammography, the breast image is captured using a special electronic x-ray detector, which converts the image into a digital picture for review on a computer monitor. With digital mammography, the magnification, orientation, brightness, and contrast of the image may be altered after the exam is completed to help the radiologist more clearly see certain areas.
Computer-aided detection (CAD) systems use a digitized mammographic image that can be obtained from either a conventional film mammogram or a digitally acquired mammogram. The computer software then searches for abnormal areas of density, mass, or calcification that may indicate the presence of cancer. The CAD system highlights these areas on the images, alerting the radiologist to the need for further analysis.
Interpretations of mammograms can be difficult because a normal breast can appear differently for each woman. Also, the appearance of an image may be compromised if there is powder or salve on the breasts or if you have undergone breast surgery. Because some breast cancers are hard to visualize, a radiologist may want to compare the image to views from previous examinations. Not all cancers of the breast can be seen on mammography.
Breast implants can also impede accurate mammogram readings because both silicone and saline implants are not transparent on x-rays and can block a clear view of the tissues behind them, especially if the implant has been placed in front of, rather than beneath, the chest muscles Experienced technologists and radiologists know how to carefully compress the breasts to improve the view without rupturing the implant.
While mammography is the best screening tool for breast cancer available today, mammograms do not detect all breast cancers. Also, a small portion of mammograms indicate that a cancer could possibly be present when it is not (called a false-positive result).