When computer-aided detection (CAD) technology for mammography first came to market, some radiologists had an almost visceral reaction against the software. Their concern was that these applications would supplant their role as diagnostician. However, as CAD achieved greater market penetration, many radiologists realized that the technology was not a threat but a powerful tool to aid their practice.
“Complex relationships exist between humans and computers,” says Robyn Birdwell, MD, from the department of radiology at Brigham and Women’s Hospital in Boston. Birdwell, writing in the October issue of Radiology, believes the preponderance of clinical evidence suggests that computer-aided detection (CAD) is a useful tool for a radiologist reading mammograms.
Yet, as she points out in her article, CAD can raise a number of issues for radiologists, ranging from sheer annoyance at the number of marks presented by the application that have to be dismissed, to the question of whether the “barrage” of false-positive marks limits the ability of a reader to see any tangible benefit from the software.
“It is only from the carefully performed clinical studies [prospective sequential read or historical control studies]…that the true impact of CAD be measured,” writes Birdwell.
Laurie Margolies, MD, director of breast imaging at Mount Sinai Medical Center in New York City, agrees that the preponderance of the literature in the field suggests that CAD provides enough of a clinical benefit that if it hasn’t already been widely adopted, it soon will be.
“The majority of the literature shows a benefit to CAD with an increased detection of cancers,” says Margolies, whose department uses iCAD SecondLook version 7.2. “So it is helpful.”
Further north in Rochester, the Elizabeth Wende Breast Care imaging center happened to be an early adopter of CAD.
“We’re breast imagers,” says Stamatia Destounis, MD, “That’s what we do. A lot of us aren’t in academic facilities—we’re in private practices and we’re reading a lot of screenings, whether they’re online, or batch reading, or in large volumes, and we’re looking for very subtle changes in mammograms from year to year.
“Breast cancer very early on can be very difficult and hard to find,” adds Destounis, “so when the Freer study came out [an article in the September 2001 issue of Radiology by Timothy Freer, MD, and Michael Ulissey, MD, that reported on a study that found 19.5 percent more cancers with CAD than without], it really made people stop and take a second look at CAD.”
So, as she puts it, Elizabeth Wende Breast Clinic “jumped on the CAD bandwagon early.”
Destounis and her colleagues at the center did their own study, published in the August 2004 issue of Radiology, that found the use of CAD helped detect breast cancers earlier. She says they found a lot of cancers they would have missed without CAD, particularly subtle calcifications that could be early cancer.
Where are the limitations?
Destounis says CAD is particularly useful in practices like hers where she screens large populations of younger women with dense breasts and difficult patterns. But she’s also careful to point out that despite the evidence of CAD’s usefulness in helping physicians identify breast cancer, she understands its limitations as well.
“It can’t do the reading for you,” says Destounis. “It needs to be used as an additional tool like everything else you have when you’re doing breast imaging, like ultrasound or biopsy.”
Margolies agrees with Destounis that CAD is a tool that a radiologist should use as one would use a magnifying glass, “or click a button on a mouse to invert the color or change the background of a digital image.” That said, she believes that a major impediment to wider adoption of the technology is the need for physicians to understand exactly how it works and how it should be used to maximize its benefits.
In the same October 2009 issue of Radiology in which Birdwell’s article appeared, Liane Philpotts, MD, department of diagnostic radiology at Yale University School of Medicine, posed the question of whether CAD could actually be detrimental to mammographic interpretation.
Philpotts argues that while CAD has potential benefits, it has important and “potentially serious limitations” as well. She suggests that in order to avoid any detrimental effect from using CAD on screening