What dense breasts are
Breasts are made of fatty tissue and glandular, fibrous tissue. When there's more glandular and fibrous tissue than fat, breasts are called dense. It's common, and it's something a radiologist sees on your compression mammogram, not something you can feel. Since September 2024, compression mammogram reports across the U.S. must tell you whether your breasts are dense.
Why it matters
On a compression mammogram, dense tissue and possible findings both show up white. Because the breast is pressed flat into a 2D image, layers of tissue overlap, and something small can be hidden behind normal tissue.
How breast CT helps
Breast CT captures the breast as a true 3D volume while it rests freely, with no compression. Our radiologists can move through it slice by slice, from any direction, instead of looking through overlapping layers. In a study of 212 patients, breast CT detected 89.2% of cancers in women with dense breasts, compared with 78.4% for compression mammography (He et al., 2016).
What to do next
Talk with your doctor about your yearly breast imaging plan. If your report says your breasts are heterogeneously or extremely dense, ask about imaging that gives a clearer picture, such as ultrasound, MRI or breast CT. Bring your density report when you visit us; it helps our radiologists.
Sources
- He et al., "Breast CT, ultrasound and mammography for detecting breast cancer," European Journal of Radiology, 2016.
- Yang et al., "Head-to-head comparison of breast CT and mammography," European Journal of Radiology, 2024.