Digital Breast Tomosynthesis (3D Mammography)
What is digital breast tomosynthesis (DBT)?
Digital breast tomosynthesis (DBT), or 3D mammography, is a machine that uses low-dose x-rays to show a three-dimensional (3D) picture of the breast. Standard, or 2D mammograms, consist of one picture of the breast, from 2 different angles: top to bottom and side to side. During a traditional 2D mammogram, the breast tissue is compressed (smushed), which results in a picture of overlapping breast tissue. This overlapping breast tissue can make the 2D images hard to read.
During a 3D mammogram, the machine moves around the breast, taking x-ray “slices” through the breast. These can be seen as single pictures or put together on the computer to make a 3D image of the breast. This view doesn’t have as much overlapping of breast tissue. 3D mammograms let the radiologist to see changes in breast tissue that would be hard or impossible to see with 2D images.
How is the test done?
The test is done using a digital mammography machine. This is the same machine used for traditional mammograms, though not all of these machines can do 3D images. The breast tissue is placed between clear plastic paddles, like with traditional mammography. The “camera” moves around the breast in an arc, taking many pictures as it goes around. The machine takes the 3D images, as well as a 2D image for comparison. Compression (pushing down) of the breast lasts just a few seconds longer than during a standard mammogram, but most patients will likely not feel a difference.
Who should get breast tomosynthesis?
Everyone who is a candidate for 2D mammography is also a candidate for tomosynthesis. Patients with dense breast tissue may benefit more from the 3D mammogram than those with more fatty breast tissue, but even fatty breasts are better seen with tomosynthesis.
Is there more radiation exposure in a 3D mammogram?
With older equipment, a patient must have both 2D pictures AND 3D pictures taken, which doubles the amount of radiation received. However, newer machines are able to create the 2D images from the 3D images. This is sometimes called “synthetic” technology. With this technology, only one set of pictures is taken, and the amount of radiation is the same as with a traditional 2D mammogram. Even for studies where the 2D and 3D images are both needed, the total dose of radiation is still under the limit set by the US Food and Drug Administration (FDA) in the Mammography Quality Standards Act (MQSA).
How do I get a 3D mammogram?
Your healthcare provider can order it, or you can ask for it at the time of the study. Not every facility offers this technology, so you need to ask your mammogram center before you go if they have 3D mammogram available.
Does the test cost more and will insurance cover it?
3D mammograms do cost more than traditional 2D mammograms. Research has shown that despite higher costs of the test, a 3D mammogram can cost less in the long run due to fewer callbacks for more images, follow-up screening, and biopsies.
Many insurance companies, including Medicare, do cover the additional costs. You should check with your insurance carrier to see if you will be covered.
What are the benefits of 3D mammography?
3D mammography reduces the number of women called back for more screenings and biopsies due to false alarms by up to 40%. This can lessen anxiety and health care costs. 3D mammography finds up to 40% more invasive breast cancers than a traditional mammogram. Invasive cancers are more likely to spread. This all adds up to better and earlier detection of breast cancer, resulting in more lives saved.
Resources for more information:
Radiological Society of North America - Breast Tomosynthesis
Breastcancer.org - Digital Tomosynthesis
American Cancer Society (2017). Mammogram Basics. Retrieved from https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/mammograms/mammogram-basics.html.
Breastcancer.org (2016). Digital Tomosynthesis. Retrieved from https://www.breastcancer.org/symptoms/testing/types/dig_tomosynth.
Radiological Society of North America (2018). Breast Tomosynthesis. Retrieved from https://www.radiologyinfo.org/en/info.cfm?pg=tomosynthesis.