Mammograms have entered a new dimension, literally. At some screening centers, women are now being offered a 3-D technology that costs more and involves more radiation but may provide a better look.
The Food and Drug Administration approved the 3-D mammography device in 2011, and the technique is becoming more common.
Radiologists who use 3-D, also known as tomosynthesis, say its drawbacks are worth the greater accuracy. By itself, 3-D mammography delivers about the same amount of radiation as standard digital 2-D mammograms. But when the FDA approved the new device, it said 3-D could be used only as an add-on to standard mammograms, essentially doubling the low radiation dose. The FDA made 3-D an add-on only because there is not enough information yet about whether 3-D screenings detect cancers as well as 2-D mammograms do. Therefore, 2-D remains the standard of care and provides unique benefits for clinicians, such as familiarity and the ability to compare images from previous years.
"The 3-D image doesn't replace the standard 2-D mammogram," says Julianne Greenberg, a radiologist at Washington Radiology Associates, which has begun telling women who come in for their standard 2-D screening that they can add a 3-D mammogram to it for $50. "Three-D is added value to an already existing, really good technology."
In a conventional mammogram, the breasts are compressed and X-rayed four times: side to side and top to bottom, for both the left and the right breast. To take the 3-D images, an arm of the machine sweeps in an arc around the breast during each of the four compressions, taking anywhere from 20 to 60 pictures to produce a 3-D rendering of the breast. These images look almost like holograms; radiologists can spin and flip them around on a computer screen, searching for cancer in the tissue and lymph nodes.