CHICAGO – Digital tomosynthesis – a technology that is only in the research phase and may be used only for investigational purposes – may be as good as or superior to diagnostic mammography in the majority of patients, according to study results presented during this week’s Radiological Society of North America (RSNA; Oak Brook, Illinois) annual meeting at McCormick Place.

Tomosynthesis obtains digital data that can be manipulated and displayed in a variety of ways, including paging through or cine display of thin sections or slices of breast tissue, which according to the study eliminates the problem of overlying tissue that might be mistaken for lesions or that may hide small cancers.

“I think tomosynthesis shows what is really going on in the breast,” said lead author Steven Poplack, MD, associate professor of diagnostic radiology and obstetrics and gynecology at the Dartmouth Hitchcock Medical Center and Dartmouth Medical School (Lebanon, New Hampshire), in an RSNA press conference.

There were 97 women in the study, all of whom had been recalled for diagnostic imaging following abnormal screening mammograms. Tomosynthesis showed it was superior to mammography in 35% of the cases, equivalent in 54% and inferior in 12%, although in the latter case, Poplack said it wasn’t really inferior, but simply didn’t characterize as well. The initial screening mammography exams showed 112 findings in the participants.

He said that by using tomosynthesis, 40% of the women who were recalled with screening mammography would not have had to be recalled for additional tests.

“The results of our preliminary trial suggest that tomosynthesis may decrease false-positive screening mammography findings by half, thereby reducing the number of women who are recalled after screening for a second, more thorough exam,” Poplack said in a prepared statement.

The aim of the study was to assess diagnostic equivalence and estimate tomosynthesis’ role in screening, or identifying tumors in women who go for a routine check-up with no symptoms.

To illustrate its imaging abilities, he showed slides demonstrating instances in which tomosynthesis clearly showed a mass when mammography was less clear.

Referring to one example, Poplack said, “Tomosynthesis clearly shows a round mass with [excellent] margin detail – that’s where the excitement comes in.”

Like mammography, with tomosynthesis the breast is compressed to flatten the breast in order to see as complete a picture of the breast as possible. A tube at the top of the device takes pictures, or “thin slices like a CT scan,” in a 30-degree arc, he said.

Poplack acknowledged that the study, sponsored by Hologic (Bedford, Massachusetts), “does not have the power to validate [the technology] to go on the market at this time.” However, he said that Hologic is planning a study of about 400 to 500 patients expected to get under way in 2006, and added that there are other studies “going on elsewhere to study tomosynthesis.” For example, he said he was aware that GE Healthcare (Waukesha, Wisconsin) has developed a tomosynthesis platform.

“I imagine that as with all [technology], most people will want to jump on the bandwagon,” he said during the press conference.

Poplack said that “one of the real benefits of this technology is that we are building on a high base of knowledge” with radiology. However, there still will be a “learning curve” for radiologists to learn how to read tomosynthesis, and those images may take longer to read, he said.

Regarding cost or reimbursement possibilities, Poplack said he “can’t speak to cost clearly,” although he did say that he expects cost savings in terms of fewer patients being called back for additional screening and fewer biopsies as a result of the clearer pictures provided by tomosynthesis. As for the outlook for reimbursement, he said the “hope is that it will be an adjunct to existing devices.”

At the Dartmouth Hitchcock Medical Center, for example, about 12% of all women screened are called back for additional imaging. Of that number, about 20% then are recalled for biopsy, and about 25% of those are determined to actually have breast cancer.

Poplack also acknowledged that as far as the comfort factor for women is concerned, some have said in surveys that they shy away from mammograms due to the discomfort of the procedure. Tomosynthesis still requires compression of the breast between paddles, and no less than mammography, because compression reduces radiation and “scatter,” among other things.

Still, he is optimistic about the technology. “I like to think that somewhere down the line it will completely replace standard mammography.”