New stereoscopic digital mammography raises breast cancer detection

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CHICAGO, Nov. 28—Stereoscopic digital mammography allows radiologists to detect more cancers with fewer false positives, according to clinical trial results presented at the 93rd annual meeting of the Radiological Society of North America (RSNA).

According to results from a current clinical trial at Emory University Breast Clinic in Atlanta, stereoscopic digital mammography, a new diagnostic technique capable of producing 3D, in-depth views of breast tissue, could significantly reduce the number of women who are recalled for additional tests following routine screening mammography. 

"Standard mammography is one of the most difficult radiographic exams to interpret," said David J. Getty, PhD, division scientist at BBN Technologies of Cambridge, Mass. "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."

"Stereo viewing is the only way to see the structure within the breast volume in true depth," said Getty. As of July 2007, 1,093 patients at elevated risk for developing breast cancer were enrolled in the trial. Each patient received a full-field, standard digital mammography screening examination and a full-field, stereoscopic digital exam, which were then read independently by different radiologists.

Getty said that a total of 259 suspicious findings were detected by the combined mammography procedures and were referred for additional diagnostic testing, including biopsy when indicated. Of those, 109 were determined to be true lesions. Standard mammography missed 40 of the 109 lesions while the stereoscopic exam failed to detect 24.

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

He said that of the 259 findings, 150 were false positives, meaning further testing revealed that no abnormality was present. Standard mammography yielded 103 false positives; stereo mammography yielded 53.

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

As a result of the interim report’s findings, researchers concluded that “stereo mammography is significantly more accurate than standard mammography in detecting lesions in breast cancer screening, improving both sensitivity and specificity.”

A total of 1,500 women at elevated risk of developing breast cancer will have received both the stereo and standard digital mammography screening exams by the end of the clinical trial this December, according to Getty.