Susan Harvey, MD, director of breast imaging in the Russell H. Morgan Department of Radiology and Radiological Science at Johns Hopkins Medicine in Baltimore.
Bottom Line: The 2-D vs. 3-D argument is over—here’s why.
The calendar says it’s time for your annual screening mammogram. You may be wondering whether you should ask for a traditional “2-D” mammogram or the newer “3-D” version you’ve heard about.
It’s really not a question. 3-D is the clear answer.
Why 3-D? Traditional 2-D mammography takes images of each compressed breast in only two directions, top to bottom and side to side. Like a photograph, in 2-D all structures appear flat and can overlap. Breast cancers can hide where tissues overlap, and overlaps can look unnecessarily suspicious, said Susan Harvey, MD, director of breast imaging at Johns Hopkins Medicine in Baltimore.
While a 3-D mammography machine looks like a 2-D machine and compresses your breasts just as a 2-D does, there’s a big difference. The top of the 3-D machine moves in an arc above each breast taking multiple images—think of each one as a thin slice—from many angles. A computer then takes all those thin slices and arranges them into a set of highly focused 3-D images for a radiologist to read. This imaging technology is called tomosynthesis.
The 3-D images make it easier to distinguish normal overlapping breast tissue from tumors, so it’s harder for cancers to hide, Dr. Harvey said. That means not just better detection but also fewer false positives and fewer callbacks, when you’re asked to come back because of a potentially abnormal finding. In other words, fewer scary moments waiting to get another test to know if something is wrong—though it’s often a false alarm, who wants a day or even a few hours of anxiety while waiting to find out?
It’s true that 3-D mammography exposes you to more radiation than 2-D does, but the extra amount is small and the total amount is small—and certainly less dangerous than having an early cancer go undetected.
Another advantage to -3D: Because 3-D mammography is better than 2-D mammography not only at finding abnormalities but also at characterizing abnormalities, women are less likely to need follow-up biopsies, which are invasive. And if you are recalled after a 3-D mammogram, there’s a greater chance than with a 2-D mammogram that a follow-up, noninvasive breast ultrasound will provide all the additional information needed.
What about women with dense breasts? Having dense breasts means you have less fatty tissue and more glandular tissue. Glandular tissue shows up white on traditional X-rays…as does abnormal tissue, making it harder to distinguish cancer on 2-D mammograms. In women with dense breasts, having a 3-D mammogram makes tumors easier to see. Note: If you have dense breasts, you might also need a breast ultrasound as an extra screening, but you may be able to schedule both tests for the same day—and have both tests covered by insurance as wellness screenings if having dense breasts is listed in your medical records. Ask your insurance provider in advance.
Even if all your previous mammograms have been in 2-D, there’s no reason not to make the switch. When 3-D first became available about eight years ago, it was hard to find centers that offered it. Now, even though it still isn’t everywhere, many breast health-imaging services offer it, even in rural areas, said Dr. Harvey. Also, when 3-D first became available, most insurance companies wouldn’t cover it. Now most do.
To find the best breast health center for you, check out our “Questions to Ask Before Your Next Mammogram.”