Breast Cancer

Mammography

Abnormal tissue shows up a dense white on mammograms, but it's not always easy to distinguish it from normal tissue. Here the top scan shows a normal breast while the bottom one shows malignant calcifications.

Mammography is a screening tool that searches for cancer when there are no symptoms of a health problem. A mammogram detects lumps, changes in breast tissue or calcifications when they're too small to be found in a physical exam. Mayo Clinic performs more than 65,000 mammograms each year.

A mammogram is an X-ray of breast tissue. Usually two images from different angles are taken of each breast. The procedure uses the X-ray images to find abnormalities within the breast tissue.

American Cancer Society guidelines recommend that all women age 40 and over have annual mammograms. A woman at high risk of breast cancer because her mother or sister was diagnosed with the disease should have her first mammogram at age 40 or 10 years before the age at which the relative was diagnosed, whichever comes first. The first mammogram done is called a baseline mammogram. This baseline becomes the standard for which all future mammograms are compared and the physician can tell if there have been any changes in the breast tissue.

A specially trained radiology technologist performs the mammogram by positioning the breast tissue in the screening equipment. Compressing or flattening the breast obtains a clearer picture of the tissue while using the lowest dose of radiation possible. The compression can be uncomfortable but will only last for a few seconds while the X-ray is taken. Some women may feel sore after a mammogram.

Sometimes, additional images for more precise pictures of the breast tissue are required. Although unsettling, this is not unusual and provides the images needed for more accurate results. A radiologist, a medical doctor trained in radiology, reads the mammogram.

Many women have dense breast tissue. This tissue appears white on the X-ray. Abnormal tissue also appears white. Because it can be difficult to distinguish between the two, the radiologist may order an ultrasound scan or, in special situations, a magnetic resonance (MR) scan.