What is it?

Mammography is a specific type of imaging that uses a low-dose x-ray system and high-contrast, high-resolution film for examination of the breasts. Successful treatment of breast cancer depends on early diagnosis. Mammography plays a central part in early detection of breast cancers. Mammography can show changes in the breast up to two years before a patient or physician can feel them. The Food and Drug Administration (FDA) says that mammography can detect 85 to 90 percent of breast cancers in women over 50. Current guidelines from the American Medical Association (AMA) and the American College of Radiology (ACR) recommend that beginning at age 40 women get annual mammograms.

What are Some Common Uses of the Procedure?

Mammography is used to diagnose breast diseases in women. The use of screening mammography can assist in the detection of disease even if you have no complaints or symptoms.

While the AMA and ACR recommend that women aged 40 and older get annual mammograms, the National Cancer Institute (NCI) says women who are at increased risk due to a genetic history of breast cancer, or who have had breast cancer, may need to get mammograms at an earlier age.

The initial two mammography images themselves are not always enough to determine the existence of a benign or malignant disease with certainty. If a suspicious finding or spot is seen, the radiologist may recommend further diagnostic studies.

How Does the Procedure Work?

The breast is exposed to a small dose of radiation to produce an image of internal breast tissue. The image of the breast is produced as a result of some of the x-rays being absorbed (attenuation) while others pass through the breast to expose the film. The exposed film is either placed in a developing machine, producing images much like the negatives from a 35-mm camera, or images are digitally stored on computer.

What are the Benefits vs. Risks?

Benefits
Imaging of the breast improves a physician's ability to detect small tumors. When tumors are small, effective treatment and cure are more likely.

The use of screening mammography (imaging examination of the breast by means of x-rays, of individuals usually without symptoms to detect those with a high probability of having breast disease) increases the detection of small abnormal tissue growths confined to the milk ducts in the breast, called ductal carcinoma in situ (DCIS). These early tumors cannot harm patients if they are removed at this stage and mammography is the only proven method to reliably detect these tumors.

Risks
Radiation exposure. Mammography is an x-ray imaging procedure. Federal mammography guidelines limit the radiation used for each exposure of the breast to 0.3 rad. The exposure to radiation received from two mammographic views is equivalent to six months of natural background exposure. This amount of exposure is believed to be safe.

Special care is taken during x-ray examinations to ensure maximum safety for the patient by shielding the abdomen and pelvis with a lead apron, with the exception of those examinations in which the abdomen and pelvis are being imaged. Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant.

False Positive Mammograms. Between 5 and 10 percent of mammogram results are abnormal and require more testing (more mammograms, fine needle aspiration, ultrasound, or biopsy), and most of the follow-up tests confirm that no cancer was present. It is estimated that a woman who has yearly mammograms between ages 40 and 49 would have about a 30 percent chance of having a false-positive mammogram at some point in that decade, and about a 7 to 8 percent chance of having a breast biopsy within the 10-year period. The estimate for false-positive mammograms is about 25 percent for women ages 50 or older.

What are the Limitations of mammography?

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 silicone 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. But the NCI says that experienced technologists and radiologists know how to carefully compress the breasts to improve the view without rupturing the implant. When making an appointment for a mammogram, women with implants should ask if the facility uses special techniques designed to accommodate them. And before the mammogram is taken, they should make sure the technologist is experienced in performing mammography on patients with breast implants.