Results of a clinical trial conducted at Emory University Breast Clinic, Atlanta, indicate that stereoscopic digital mammography could reduce the number of women recalled for additional tests following screening for breast cancer, and could even contribute to the earlier detection of cancer.

"Standard mammography is one of the most difficult radiologic exams to interpret," said David J. Getty, PhD, division scientist at BBN Technologies, Cambridge, Mass, who has been developing the technology for 12 years. "In a two-dimensional image of the breast, subtle lesions may be masked by underlying or overlying normal tissue and thus be missed, and normal tissue scattered at different depths can align to mimic a lesion, leading to false-positive detections."

The trial involves 1,093 patients at elevated risk for breast cancer; patients received both a full-field digital mammography screening exam and a full-field stereoscopic digital exam, and the results were compared.

"Stereo viewing is the only way to see the structure within the breast volume in full depth," Getty said.

The two types of study were evaluated independently by separate radiologists who reported a total of 259 suspicious findings. Additional diagnostic testing, including biopsy in some cases, revealed that 109 were true lesions; standard mammography failed to detect 40 lesions, stereo mammography 24.

"Our early results suggest that stereo digital mammography could contribute to the earlier detection of cancer," said Getty. "A small percentage of the additional lesions missed by standard mammography but detected by stereoscopic mammography will turn out to be cancerous."

Stereo mammography was also shown to reduce false positives compared with standard mammography. Of the 259 suspicious findings, 150 were false positives; 103 of those came from standard mammo, while just 53 came from the stereoscopic technique.

"In our study, stereo digital mammography reduced false positives by 49%," said Getty. "This could have a significant impact by cutting in half the number of women who are needlessly recalled for additional diagnostic workups, resulting in a large savings in cost and patient anxiety."

The study's initial findings were presented at the 2007 meeting of the Radiological Society of North America (RSNA), Oak Brook, Ill. Getty says equipping digital mammography equipment and software with stereoscopic capabilities would involve only minor changes.