Digital tomosynthesis (also called 3D mammography) creates a three-dimensional picture of the breast using x-rays. Several low-dose images from different angles around the breast are used to create the final 3-D picture.
A conventional mammogram creates a two-dimensional image of the breast from two x-ray images of each breast.
Digital tomosynthesis is approved by the U.S. Food and Drug Administration, but is not yet considered the standard of care for breast cancer screening. Because it is relatively new, it’s available at a limited number of hospitals.
A Norwegian study has found that when digital tomosynthesis was combined with conventional digital mammography, invasive breast cancer detection improved by 40% and false-positives decreased by 15%.
A false positive is an abnormality that looks like a cancer, but turns out to be normal. Besides worrying about being diagnosed with breast cancer, a false positive means more tests and follow-up visits, which can be stressful.
The study was published online on Jan. 7 by the journal Radiology. Read the abstract of “Comparison of Digital Mammography Alone and Digital Mammography Plus Tomosynthesis in a Population-based Screening Program.”
The researchers screened about 12,500 women with both digital mammography and digital tomosynthesis. Each image was read by four experienced radiologists.
Using mammogram results alone, the radiologists found 77 cancers. Using both mammogram and digital tomosynthesis results together increased the number of cancers found to 101.
False positive rates dropped from 61.1 per 1,000 screenings for mammography alone, to 53.1 per 1,000 screenings when digital tomosynthesis was added.
The researchers also looked to see if adding digital tomosynthesis improved detection of specific types of breast cancer:
- mammography plus digital tomosynthesis found 81 invasive cancers
- mammography alone found 56 invasive cancers
So adding digital tomosynthesis to digital mammography improved detection of invasive breast cancer by 40%. Combining the two types of screening also improved detection of higher-grade cancers by 26%.
The results of this study are very promising and add to earlier research results suggesting the benefits of combining digital tomosynthesis with digital mammography.
Still, more research needs to be done before digital tomosynthesis becomes part of routine breast cancer screening. Because it is another imaging test, digital tomosynthesis exposes women to additional radiation. Researchers are looking at ways to replace a standard mammogram image with one created from digital tomosynthesis images to reduce radiation exposure.
Visit the Breastcancer.org Digital Tomosynthesis page to learn more about how the test is done and how it’s different from a mammogram.