When breasts are made up of more fibroglandular tissue than fatty tissue, they are considered dense. Having dense breast tissue is usually inherited, but young age, weight loss with a reduction in body mass index or receiving hormone therapy can also influence your breast tissue. 

Breast density is classified into four categories. When you get a mammogram, the radiologist who interprets your images can determine if you have dense breasts and which category you match. Your breast tissue can be:

  • Almost entirely fat
  • Scattered fibroglandular
  • Heterogeneously dense
  • Extremely dense

If your mammogram reading falls within one of the last two categories, you have dense breasts. About 40% of screening-age women (40 and older) fall into the heterogeneously dense category and 10% fall into the extremely dense category, so a mammogram reading that depicts dense breasts is a common finding.

What does this mean for you?

It is important for women to know the implications of having dense breasts. In April 2018, Wisconsin legislation began requiring mammography facilities to notify patients if they have dense breasts. As of September 2024, the FDA will begin requiring mammography facilities to notify all patients of their breast density — whether dense or not dense.

Dense breast tissue can influence the ability to detect cancer on a mammogram. Because dense breast tissue and tumors both appear white on a mammogram, it can be difficult to tell the difference between the two and see potential abnormalities. The more dense the breast tissue, the higher the likelihood that cancer can be hidden. That being said, annual screening mammography starting at age 40 has been shown to reduce deaths from breast cancer even in women with dense breasts.

Additional Screening Options

Since dense breasts make it harder to detect breast cancer with a mammogram, additional screening exams can be considered. The following three types of supplemental screening exams allow radiologists a deeper look at dense breast tissue to more accurately determine the possibility of underlying cancer:

Breast MRI

In women who have dense breast tissue, breast MRI with IV contrast, when combined with yearly mammograms, detects more cancers than mammography alone. There are different types of breast MRIs for women with dense breast tissue, depending on their personal risk factors for breast cancer. Women who are at higher risk for breast cancer should have a longer, more in-depth MRI designed for women at high risk of developing breast cancer.

The American College of Radiology defines high-risk women as those with certain genetic mutations, a history of chest radiation therapy, a personal history of breast cancer, or a calculated lifetime risk of 20% or more when evaluated with a risk assessment model. Women who have dense breasts but do not have other factors that put them at high risk for developing breast cancer are eligible for a shortened, abbreviated (also called “fast”) breast MRI. 

If you have questions, talk with your doctor or clinician about the type of MRI that may benefit you. The higher cost of MRI and sometimes, limited availability, requires appropriate use of this supplemental imaging method, and it should never be used to replace yearly mammograms. Insurance coverage varies, so contact your insurance provider before having MRI tests.

Insurance coverage for these additional screening options varies, so contact your insurance provider.

Ultrasound Screening Exam 

A specialized type of ultrasound called automated breast ultrasound (ABUS) uses ultrasound technology to detect breast cancer in women with dense breast tissue. With ABUS screening images, dense breast tissue appears white, but cancer appears grey. In regular mammogram images, dense breast tissue and cancer both appear white. ABUS technology allows breast tissue to be looked at in a different way and allows detection of abnormalities that would be hidden by dense breast tissue on a mammogram. However, ABUS does not replace the mammogram. It should be used in addition to an annual mammogram, if your doctor recommends it.

Who reads your mammogram? It matters.

At all of our locations, breast imaging exams are interpreted by highly trained breast imaging radiologists. These specialists interpret thousands of mammograms each year and have the expertise to detect very subtle changes in breast tissue. 

“Women need to know how important it is to have a breast-focused radiologist interpret their mammogram,” said Shadie Majidi, MD, a radiologist and section chief of Breast Imaging for the Froedtert & MCW health network. “It can make a big difference in detecting cancer as early as possible, and we know that early detection of breast cancer can save lives.” 

The Froedtert & MCW health network offers multiple locations throughout southeastern Wisconsin for breast cancer screening. In addition, several Froedtert & MCW locations offer same-day results for diagnostic breast imaging, including Froedtert Hospital, Froedtert Menomonee Falls Hospital, Froedtert West Bend Hospital, Drexel Town Square Health Center, Mequon Health Center and Froedtert & MCW RAYUS Radiology at Westbrook Health Center.
 

 

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Cancer

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