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Radiologists disagree in digital debate

Radiology Administrator's Compliance and Reimbursement Insider, January 1, 2005

In November, one radiologist told MRR that there was no scientific evidence favoring digital mammography over analog and that the perceived advantage of digital (i.e., greater detail) could be a drawback-particularly when calcium deposits are involved.

The radiologist did not want to be identified because his facility is using digital equipment while national studies continue. Although digital mammograms find more suspicious items, many of those turn out to be benign, says the radiologist. In his experience, the threshold for suspicion should be a spot big enough to be able to be seen by ultrasound (6 mm-8 mm), but digital scanning picks up everything down to 4 mm. "Regarding calcium, digital mammography would not be that meaningful," he says. "It would show up a lot of noise that would necessitate a six-month follow up-with all the anxiety in the interim."

Rather than chasing everything at 4 mm, he says, consider that radiologists "can be equally criticized for workups that lower the bar for false positives." He believes current national studies will show that for masses, digital is "a little better, but for calcium deposits, it's not as good" as analog mammography.

Officially, the jury is still out. The results of national trials are due this spring, says Dr. Etta Pisano, chief of breast imaging at the University of North Carolina School of Medicine in Chapel Hill, who coordinates the tests. Nonetheless, radiologists who have used the digital systems cite pros and cons.

Wende Logan-Young, MD, director of the Elizabeth Wende Breast Clinic in Rochester, NY, says her facility has used the General Electric, Hologic, and Fischer systems, putting her in a good vantage point to gauge the equipment.

"Every day, we do online evaluations with the manufacturers," says Logan-Young, "and if something needs fixing, they fix it. No one unit is just right, but they're all working to get theirs to be just right. It's a work in progress."

At presstime, four manufacturers had six full field digital mammography systems approved for use in the United States. They include

  • GE Senographe 2000D and DS

  • Fischer Imaging SenoScan

  • Lorad/Hologic Selenia and Digital Breast Imager

  • Siemens Mammomat Novation DR

    Fujifilm Medical Systems also makes a system, about 1,500 of which are in use worldwide. The FDA has yet to approve Fuji Computed Radiography for use in the United States. The FDA did recently approve the workstation built by the Swedish company Sectra. The workstation is an accessory used to carry data from a mammography unit.

    Pisano does not think the machines changed much during or since the clinical trials. "The detectors are substantially the same," she says, "but the image processing may be different. That's why we're running reader studies up to the last minute."

    Pisano constantly asks the manufacturers for the latest and greatest in softcopy display, using the same cancers and noncancers to test the reading accuracy.

    The Wende clinic, which performs about 75,000 mammograms a year, has used the Fischer and Hologic systems since fall 2003, and it received the Sectra Workstation and GE unit this summer. Although she could not single out one system as the overall best, Logan-Young did pinpoint some difficulties and advantages. GE, the first system brought to market in the United States (in 1999), "has eliminated a lot of its problems," she says, noting that "its software is good." However, she points out, GE uses a 100 micron pixel image, enabling sharper image resolution, whereas others use smaller pixels.

    However, GE comes with a smaller film tray, "so you can't do [the whole] breast. If you have a large-breasted patient, you have to have multiple exposures," says Logan-Young. Siemens and Hologic promote their large (24 cm x 29 cm) image areas. All the systems tout their compatibility with CAD, paddle comfort, and networking components.

    Hologic uses 70-micron pixels, whereas Fischer and Sectra have 50-micron panels, affording "the best resolution, but they're harder to work with" than GE and Hologic, says Logan-Young. She says she has a good deal of experience working with photographic equipment, "and with the grain size it now has, film is about as good as it's going to get," she says.

    "Digital is definitely the future. But the potential has not yet been realized. If there is a difference between digital and traditional imaging, it's minimal," says Logan-Young. And then there's the problem of how to pay for it.

    Mark Segel, MD, chief of breast imaging at St. Joseph's Mercy Hospital in Macomb, MI, echoes Logan-Young's opinion that the cost-benefit ratio is dubious at this stage. He believes that "if you're looking at digital v. analog, you have to look at value-oriented healthcare. It may be smarter to replace aging analog equipment that invest in digital."

    Manufacturers emphasize the assets of digital mammography, saying the systems, which cost about $450,000, are medically and financially valuable because

  • they enable the physician to electronically manipulate (e.g., enlarge, contrast, shape, lighten, or zoom in on) the breast images (much like a digital camera allows the photographer to optimize the picture) by putting the film in a computer and adjusting the light and size

  • fewer callbacks are needed because the detailed digital images are more precise than film

  • the facility and the patient save time

  • consultations and access are more efficient because the images can be electronically beamed to another site

  • lower-radiation doses may be used, especially on large-breasted women

  • higher volume is possible, which is especially important when screening large numbers of healthy women

    Read times

    Another shortcoming mentioned by a physician who did not want to be named was that it took significantly longer to read digital pictures on the screen. "At one point, we were printing out hard copies to read, which defeats the purpose" of the GE digital system his facility uses, he says. "We have to figure out a way to cut back on the time" entailed in digital readings, he adds, because "in modern medicine, you have to increase your throughput. And anything that makes you less efficient is a problem."

    Conversely, another concern is that the technology available with digital screening and CAD could lead to an over-reliance on the systems.

    "If the computer doesn't say anything is suspicious, you stop searching. The computer does the work for you. But the computer is not perfect," said one radiologist.

    Pisano's verdict is still out. "I'm a proponent of whatever helps women," she says, "and if it turns out digital is more expensive but not any better than film, then I'm not for it. That's what we're waiting to see."

    Insider source:

    Nancy Gaines, RACRI correspondant. E-mail R NGaines@aol.com or call 978/282-0351.