Stereo mammography boosts accuracy but doubles dose

Emory University trial results showed that a new technique called stereoscopic digital mammography reduces false positives by 49% and false negatives by 40% in women with an elevated risk of breast cancer. But the technique may have difficulty catching on, as it requires double the images and double the radiation dose compared with conventional digital mammography.

With stereo mammography, a digital image is taken, then the x-ray tube is moved 6 degrees to 10 degrees in another direction and a second image is acquired for each view. So instead of four images per patient, eight are required. A stereo mammography display station allows radiologists to view digital images of the breast structure in 3D with special polarized glasses.

"It may not be justified for a very large screening population (40 million women). However, if you reduce the dose from diagnostic studies because you're calling back fewer women, it could be dose-effective," coauthor Dr. Carl D'Orsi, director of breast imaging at Emory, told Diagnostic Imaging.

It also is possible that stereo mammography could be used in conjunction with tomosynthesis, D'Orsi said. Tomosynthesis may have problems with detection and analysis of calcifications, since it is a slice technique. But a reader could reconstruct stereo images from the tomosynthesis exam, with no dose penalty.

"Thus a reader will have both tomo and stereo mammography at their fingertips, with a dose equivalent to a standard 2D mammogram," he said.