3-D Breast Imaging May Improve Cancer Detection
WEDNESDAY Nov. 28, 2007 -- A 3-D view of breast tissue may give women a more accurate method of detecting breast cancers, according to a trial of a new technology called stereoscopic digital mammography.
False-positive results were almost cut in half with stereo mammography, said the technology's developer David Getty, a division scientist at BBN Technologies in Cambridge, Mass.
"These are women who at the moment are getting a call back from a radiologist saying something suspicious has been found," he explained. However, after subsequent testing, "most of them are finding out there was nothing there," Getty added.
"Being able to cut that number in half would have a dramatic impact" in reducing both patient anxieties and cost, he said.
A second dramatic benefit to the new technology lies in "finding lesions that are being missed on standard mammography. Most of them will turn out to be benign, but some additional cancers will be found," Getty said.
Getty was expected to present the results Wednesday at the Radiological Society of North America's annual meeting in Chicago.
The five-year trial, conducted at Emory University in Atlanta and scheduled to end in December, focused on almost 1,100 women at elevated risk for breast cancer. According to Getty, the trial was a collaboration with Dr. Carl D'Orsi, the director of Emory's breast imaging center.
Results so far show that that stereo mammography reduced false-positives by 49 percent. The stereoscopic equipment failed to detect 24 out of 109 cancerous lesions, compared to 40 out of 109 lesions not found through standard digital mammography, Getty said.
Another advantage of the stereoscopic digital mammography is that it "is much better at picking up cluster calcifications [that] can be associated with malignancy," Getty added.
This technology also allows radiologists to get a picture of the entire breast volume in a slice-by-slice view. "It certainly helps, because you're seeing all of the tissue in depth," Getty explained. The capacity of mammography to detect problems in dense breasts is not an issue with the stereoscopic digital equipment because it "doesn't look as dense, because tissue is being spread out in depth," he said.
A stereoscopic mammogram image works on principles similar to the old Viewmaster slide viewers used by children, Getty explained. Each of two images inserted in the Viewmaster were channeled to a different eye, and the brain's "visual cortex -- the magician in all this -- then combines the two images, artificially recreating what your two eyes normally create when you walk around in a three-dimensional world," Getty said. Similarly, the viewing monitor for stereo mammography merges two distinct images to create a 3-D look at tissue.
Experts say stereo mammography does show promise, but more work is needed.
"Stereo mammography is a step in the right direction, but it is not a breakthrough," said Dr. David Bluemke, a professor of radiology and medicine at Johns Hopkins Medical Institutions in Baltimore. "True 3-D tomographic imaging of the breast is ultimately needed." By giving radiologist a view of slices through the breast, 3-D tomography would allow radiologist to see lesions that are otherwise obscured by being superimposed on normal breast tissue, he explained.
Stereoscopic digital mammography "seems very promising," added Dr. Kristin Byrne, the chief of breast imaging at Lenox Hill Hospital in New York City. "It would make mammography that much better."
With current technology, the problem of calling back a woman whose breasts show a suspicious area is that radiologists often can't find that same suspicious tissue in a second view, so the woman has to follow-up with further monitoring in another six months or have a biopsy, she noted.
There's more on breast cancer at the U.S. National Cancer Institute.
Posted: November 2007