Q. My mammogram report states that I have heterogeneously dense breast tissue. What does that mean?

A. Breast tissue is a mix of glandular tissue (used for making milk), fatty tissue (used as the substrates for making milk) and fibrous tissue (used to hold up the breasts and give them composition). Each woman has a different mix of these tissues, simply by virtue of the way she was born – her genetics.

Heterogeneously dense breast tissue is when more than 50 percent of the breast tissue is fibrous and glandular. The significance of dense breast tissue is that fibrous and glandular tissues tend to be white on a mammogram, and unfortunately, breast cancer is also white on a mammogram, so dense breast tissue can sometimes hide a small cancer.

New 3D technology, called tomosynthesis, can help us see through this dense breast tissue, and occasionally, with women who have elevated risk factors, an adjunct study like sonography or MRI might help. Reputable websites, such as The American Cancer Society and Breast Diagnostic Center, have more information on Dense Breast Tissue.

Q. Why is compression necessary for a mammogram?

A. A mammogram is a modified X-ray, and the technology relies on pushing the X-ray beam through breast tissue. If the tissue is thicker in the back than it is in the front, the beam does not push through with even exposure, and you get a mammogram that is difficult, if not sometimes impossible, to read.

By using mild compression we can get an even thickness to the breast and a good mammogram result. Thus we maximize our chances to catch that small cancer as early as possible.

Anecdotally, many women have said that the compression in a 3D mammogram is less painful than with mammograms they have had in the past.

Michael J. Ulissey, M.D., is a partner at the Breast Diagnostic Centers of Auburn and Federal Way. He received his medical degree from Texas A&M University, College of Medicine and subsequently served as a physician in the U.S. Navy. His career since has been a mix of private practice, academic teaching and research in the fields of breast imaging, breast cancer and early detection. In addition to taking care of patients locally, he continues to participate in research as an Adjunct Professor at the University of Texas Health Sciences Center. You can reach him at Mike@breastdiagnostic.com.