3-D Scan May Help Detect Breast Cancer
Study: Stereoscopic Mammography May Have Advantages Over Standard Mammography
Nov. 28, 2007 (Chicago) -- A novel imaging scan that offers a 3-D view of the breast appears to be more accurate at spotting breast cancer than currently used techniques, researchers report.
The method, called stereoscopic digital mammography, reduced the number of false positives by 49%, compared with standard digital mammography, says David J. Getty, PhD, division scientist at BBN Technologies of Cambridge, Mass.
"This means many fewer women would be unnecessarily recalled for additional diagnostic workups, resulting in reduced health care costs and patient anxiety," he tells WebMD.
The number of false negatives -- missed cancers -- was cut by nearly 40%, says Getty, who has been working on the development of the technology over the past 12 years.
That finding could have been due to chance. But Getty says he thinks that it will take on what researchers call statistical significance -- meaning there's less than five-in-100 odds that it is due to chance -- as more women are studied.
Getty presented results of the first 1,093 women to be enrolled in a trial pitting stereoscopic digital mammography against standard digital mammography in women at high risk of breast cancer at the annual meeting of the Radiological Society of North America.
By the end of the five-year trial this December, 1,500 women will have been enrolled.
Creating a 3-D Breast Image
Carl D'Orsi, MD, director of the breast imaging center at Emory University in Atlanta, where the trial is being conducted, says another advantage of the new technique is that it reduced by 80% the number of missed calcium lesions in the breast.
"These lesions are the first indicator of the earliest type of breast cancer, ductal carcinoma in situ (DCIS)," he tells WebMD. In DCIS, cancer cells have not yet spread beyond the ducts of the breast, so it is highly curable.
Getty says that standard mammography exams, in which radiologists take two two-dimensional pictures of the breast (one vertical, one side-to-side), are difficult to interpret.
"Subtle lesions may be masked by underlying or overlying normal tissue," he says. "And normal tissue scattered at different depths can align to mimic a lesion, leading to false positives."
Stereoscopic digital mammography gets around those problems by giving the radiologist a picture of the entire breast in depth, Getty says.
Each of two digital X-ray images taken from two different points of view is merged on a stereo display workstation to create a 3-D view of the breast.
"It's like seeing a 3-D movie with polarized glasses," he says.
Comparing Standard and Stereo Mammography
In the study, all the women were screened using both stereo and standard digital mammography.
Independent radiologists who reviewed the images discovered 259 suspicious findings. Additional testing, including biopsies when needed, confirmed that 109 were cancer.
Results showed that:
- Standard digital mammography missed 40 of the 109 lesions, while stereo mammography missed 24.
- Standard mammography produced 103 false positives, while stereo mammography found 53.
- Standard mammography missed 20 calcium lesions, while stereo mammography missed only four.
Joseph H. Tashjian, MD, president of St. Paul Radiology in Minnesota and moderator of a news conference to discuss the findings, tells WebMD that the new scan shows a lot of promise.
"It allows you to see in 3-D and see depth," he says.
But further study is needed to determine whether a stereo image of the breast is better than having two images as with standard mammography, Tashjian says.
One of the "really nice things" about the technology, he adds, is that it only entails minor changes to standard digital mammography equipment and software.
BBN Technologies developed the workstation used in the trial. The Department of Defense funded the study.