CHICAGO — Breast tomosynthesis was equivalent or superior to conventional diagnostic mammography in 9 of 10 women in a preliminary study of 98 women.
“In a screening capacity, we estimate about a 40% decrease in screening mammography, which would be a huge benefit to women and public health to save the patient the anxiety, cost, and time of going for diagnostic evaluation,” lead author Dr. Steven P. Poplack said at the annual meeting of the Radiological Society of North America. Nationally, about 12% of all screening mammograms are recalled for additional evaluation.
The investigational three-dimensional technique uses conventional x-ray tubes and digital imaging plates. But a series of low-dose exposures are made every few degrees while the x-ray tube is rotated over the patient in a 30-degree arc, creating a series of digital images.
The individual digital images are then reconstructed into a series of thin, high-resolution slices that can be displayed individually or in a dynamic cine mode, said Dr. Poplack, who serves as a scientific advisory board member for Hologic Inc., which sponsored the study.
He presented data from a study in which 98 women with abnormal digital screening mammograms were sequentially recruited and underwent tomosynthesis of the affected breasts.
Tomosynthesis images were evaluated prospectively and compared with the initial screening mammography exams showing 112 findings in the women.
Tomosynthesis detected five invasive carcinomas in 4 of the 98 women, including one lesion that was not apparent on digital mammography.
As a diagnostic imaging technique, tomosynthesis was equivalent (60/112) or superior (39/112) to diagnostic mammography in 86 of 98 (88%) women. Half (49) of the women would not have been recalled if tomosynthesis had been used on the first screening.
The advantage of tomosynthesis is its ability to reduce or eliminate the tissue overlap and structure noise seen in single-slice two-dimensional mammography, said Dr. Poplack of Dartmouth Medical School, Hanover, N.H.
“It's my own belief that not only are we going to get benefit in specificity, but we're also going to get a benefit in sensitivity and decrease our false-negative rate,” he said.
Another benefit of tomosynthesis is that it builds on a huge base of knowledge already established in mammography, so the images will not be foreign to radiologists. It requires the same amount of compression as film or digital mammography, so the discomfort is no less for the patient, however.
Dr. Poplack cautioned that the results are preliminary, and that the study was too small to identify characteristics of women in whom tomosynthesis might offer the greatest benefit.