Q. A patient recently read an article that talked about dense breast tissue and asked me why some cancers are seen on ultrasound yet not seen on mammograms? She also asked me whether she should get supplemental screening with ultrasound.

A. No test in medicine is perfect, including mammography. A mammogram will find early stage breast cancer about 85 to 90 percent of the time, yet it does have one Achilles’ heel, and that is dense breast tissue.

Normal tissue on a mammogram is white, and breast cancer on a mammogram is also white, so we have to tell the good white from the bad white. When a woman has dense breast tissue, she has a lot of natural white background, so small cancers can sometimes hide in this otherwise normal background of dense white tissue.

Ultrasound, when added to a mammogram (not done in place of one, but added to one) that has dense breast tissue, can often detect these small cancers that were hidden on the mammogram, thus still giving that woman a great chance at early detection and an easy cure.

So ask your radiologist whether you have dense breast tissue, and if the answer is “yes,” then ask him or her if their center will do an automated whole breast screening ultrasound of both sides.

Michael J. Ulissey, M.D., is a partner at the Breast Diagnostic Centers of Auburn and Federal Way. 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.