Delving into Digital Breast Tomosynthesis

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Breast-Tomo.jpg - Breast Tomo
Screening patient whose cancer in her right breast was not seen on standard 2D mammography (left) but was identified by tomosynthesis (right).”
Source: Emily Conant, MD

You hear about it on the radio, on TV and see it in the health system newsletter. Your facility has bought in or is close to sending out an RFP. The buzz is all about digital breast tomosynthesis (DBT). Experts weigh in on its prowess, performance and power in cutting recalls. Is it ready for primetime?

Tomosynthesis’ uniqueness comes from its joint 2D and 3D imaging capabilities, producing a comprehensive image of the breast. With an increase in cancer detection rates, enthusiasm has spread rapidly, largely due to the results of two marquee studies: the Oslo Breast Screening Trial from Per Skaane, MD, PhD, of Oslo University Hospital Ullevaal in Norway, and colleagues, and the Italian STORM study from Francesca Caumo, MD, of the Centro di Prevenzione Senologica in Verona, Italy, and colleagues. Both studies demonstrated an increase in cancer detection rates and a decrease in false-positive recalls with DBT, leading to a fairly quick adoption of tomosynthesis in clinical practices.

The technology has proven effective as well. Brian M. Haas, MD, of Yale University in New Haven, Conn., and colleagues found a 30 percent reduction in recalls (Radiology 2013; 269:694-700). Stephen L. Rose, MD, of the TOPS Comprehensive Breast Center in Houston, and colleagues discovered a 37 percent recall reduction, as published in the June 2013 issue of American Journal of Roentgenology. As for cancer detection, Hass et al showcased a 9.5 percent increase in detection rate. Rose and colleagues found a 35 percent increase in detection.

“In our experience, invasive cancer detection is up 27 percent, which closely mirrors that of the large Norwegian study,” says Emily Conant, MD, of the Perelman School of Medicine at the University of Pennsylvania in Philadelphia. “This means that in our ongoing ‘natural experiment’ in which we have been imaging all of our over 22,000 screening patients with tomosynthesis, our cancer detection rate is up, particularly for the most clinically significant cancers: the invasive ones.”

Screening patients with dense breasts is one area experts wonder if tomosynthesis will have an impact, as mammography currently misses about half the cancers in dense breasts. As legislation requiring breast density notification, which is currently implemented in 14 states, informs more women about their breast composition, more are expected to request supplemental screening.

“We will need good data based on density, age and complexity to see if dense breast legislation will influence the use of tomosynthesis,” continues Conant. “Early literature shows that DBT reduces recall rates and increases detection rates across all densities, which suggests that these outcomes are due to more than density alone. Perhaps the improvements with tomosynthesis are due to other complementary factors, such as breast texture or the complexity of the image.”

“More and more practices are incorporating tomosynthesis into screening programs,” says Constance Lehman, MD, PhD, FACR, of the University of Washington in Seattle. “The technology went through a lot of iterations, and it took a lot of time to get to where it is today. However, the impact of this technology on clinical outcomes for our patients needs careful evaluation and the information to date is still preliminary.”

Some echo this idea and are more hesitant to fully embrace DBT just yet. David Dershaw, MD, FACR, of Memorial Sloan Kettering Cancer Center in New York City, says: “I know a lot of people have acquired tomosynthesis and are using it. There’s a moderate amount of enthusiasm about the whole thing, but in terms of published numbers there’s not very much out there.”

Going with the flow

Despite the many promises tomosynthesis has to offer for breast screening and detection, concerns remain. In particular, the technology presents challenges to radiology workflow due to the complexity of the images produced.

“Radiologists are spending twice as much time with tomosynthesis as a screening study, which is about 90 seconds of interpretation,” says Christoph Lee, MD, MSHS, of the University of Washington in Seattle. “However, the amount of time invested in screening interpretation may be compensated with the amount of time saved on the diagnostic end.” Lee suggests that a possible solution for workflow issues may be found in batched screening, allowing radiologists to use a quiet room to avoid interruption and read multiple studies at a time.

“Literature is saying that the interpretation