3-D tomosynthesis: A new mammography refinement

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Mammographer at WorkThe usefulness and guidelines for screening mammography have been hotly debated for years. Some have questioned whether the technique finds too many lesions that would not progress to threaten a woman s life, and there has been additional debate about the age at which regular screening should start. Now a study suggests that a newer technique 3-D tomosynthesis might help resolve some of the debated issues.

A digital mammogram is produced when a low-dose X-ray is taken of a woman s breast: the X-ray machine is stationary. Tomosynthesis involves an X-ray machine that moves in an arc around the breast, taking many images that can then be compiled to make a three-dimensional image of the tissue.

Dr. Sarah M. Friedewald from the Advocate Lutheran General Hospital in Park Ridge, IL and colleagues from multiple institutions performed a retrospective study of women at 13 breast centers. The records from two periods were examined: period 1 included women who had only digital mammograms, while period 2 included women who had both digital mammography plus tomosynthesis examinations.

In all, nearly 455,000 records were evaluated: about 281,000 from period 1, and about 174,000 from period 2. They found that the recall rate (the rate at which women were asked to return for a second examination) was significantly lower when tomosynthesis was added to digital mammography: 91 women per 1000 vs 107 respectively. The number of biopsies required after recall were also lower in the records from period 2. Further, the rate of invasive cancer detection was greater in period 2 (5.4 per 1000 vs 4.2).

Overall, the authors concluded that adding 3-D tomosynthesis to digital mammography was linked to a lower recall rate and a better rate of cancer detection. So should breast centers run, not walk, to add tomosynthesis machines to their armamentarium? Probably not yet, said Drs Etta D. Pisano an Martin J. Yaffe in an associated editorial.

These writers pointed out that while Tomosynthesis potentially improves sensitivity while addressing the 2 most common arguments against mammography screening false-positive findings and overdiagnosis, the fact that this study was both retrospective and non-randomized precluded attributing causality to the results. Further, they pointed out that the tomosynthesis equipment costs about twice as much as that for digital mammograms; and breast centers would do well to wait for further validation of the technique before jumping on board.

ACSH s Dr. Ruth Kava concurs, saying It certainly would be great to have a technology that is more definitive in screening for breast cancer than the current mode. However, it s crucial to get this right so more work must be done to validate tomosynthesis. Hopefully it will support the results of the current work.