With no magic bullet or blood test to detect breast cancer, radiologists like Debra Ikeda, MD, are always investigating new technologies to improve early detection of tumors. Ikeda first saw 3D tomosynthesis in 2006, and she's been waiting for FDA approval in the U.S. to bring it to Stanford. Beginning in May of this year, Stanford will be opening two 3D tomosynthesis mammography systems at its two breast imaging centers in Palo Alto.
"The problem women face in mammography is that a small cancer can be hidden by breast tissue overlying or underlying it," says Ikeda, a professor of radiology who directs Stanford's Breast Imaging Section. "With 3D tomosynthesis, we'll be able to see a finding that was previously hidden."
In numerous research studies conducted in Europe, 3D tomosynthesis in combination with 2D mammography provides about a 25% improvement in overall cancer detection rates; and a 15% reduction in false positives. "This greatly reduces the number of women who have to be called back for secondary testing," says Ikeda. Further studies were conducted on the use of 3D tomosynthesis alone, with C-View software to create the 2D image, and the results were equally promising.
"Now we can find many little cancers that were being obscured by dense tissue," she says.
How it works
During 3D mammography, women undergo a traditional 2D mammogram, and then an x-ray arm sweeps in a slight arc over the breast and takes multiple images. Essentially, it's like getting two mammograms but with only one breast compression. However, this approach emits twice the amount of radiation, but is still within the limits deemed safe by the FDA.
Women who come to Stanford soon will have another option. Stanford has invested in C-View (synthesized view) software, which essentially eliminates the need for the 2D mammogram, and reduces the overall radiation exposure of the exam.
"With synthesized view, you take all the images in 3D slices and then use the computer software to reconstruct an image of the entire breast without taking another picture," says Ikeda. By looking at breast tissue in slices, 3D mammography can show cancers missed by conventional 2D mammography.
Who receives 3D tomo?
Small breast cancers can go undetected in women with dense breast tissue, as well as in women with less dense breasts, says Ikeda. So every woman who comes to Stanford for screening will be offered 3D tomosynthesis.
"3D is especially good at finding small, stellate cancers," she says, "and it will be really helpful in finding secondary small tumors in women who already have one small cancer." But Ikeda cautions that tomosynthesis still misses some cancers, especially round tumors hidden among dense tissue. Finding those types of cancer will take a different type of technology such as contrast-enhanced mammography, which Stanford plans to add next year.