CHAPEL HILL - Images of the female breast created digitally could lead to more accurate breast cancer screening and diagnoses than traditional X-ray films, according to a new study.
The research, conducted by University of North Carolina at Chapel Hill School of Medicine scientists and colleagues, shows radiologists often prefer digital images over film because they provide better information on which to base diagnoses, said lead researcher Dr. Etta Pisano.
Eventually, the hope is that fewer women will die of breast cancer because their tumors will be found and treated earlier through the new technology, scientists say.
Pisano, associate professor of radiology and director of breast imaging at the UNC Lineberger Comprehensive Cancer Center, and collaborators are presenting their findings in Chicago this week at the Radiologic Society of North America's annual meeting. The work is displayed in a poster session that will remain up through Friday, Dec. 4.
"Digital mammography is making a big splash at the meeting, just as we thought it would," Pisano said. "We predict that it ultimately will replace film screen mammography."
Once a technician creates a traditional film screen mammogram, it cannot be altered, she said. Since breast tumors and healthy breast tissues are so similar in density, up to 20 percent of breast cancers cannot be seen at all on X-ray film.
"What you see is what you get," the physician said. "Improvements in image display involve acquiring more images with magnification or focal compression and thus exposing the patient to more radiation or looking at the images with a hot light and magnifying glass."
Digital systems, on the other hand, directly measure X-ray photons and can be processed by a computer and displayed in different ways, Pisano said. Radiologists can manipulate the resulting pictures by changing the brightness, contrast and other characteristics like viewers can alter picture quality on a television set.
Researchers asked 12 certified, working radiologists in Chapel Hill, Durham, Raleigh and Graham to look at, compare and grade images resulting from the old and new technologies for screening and diagnosis of breast masses and calcifications. Each spent more than five hours providing their evaluations.
"It was clear that the radiologists preferred to look at different versions of the image for each of the three tasks," Pisano said. "In other words, what they liked for screening is not the same thing they liked for diagnosis of masses or diagnosing calcifications. The bottom line is that they need multiple versions of the same image to get as much information out of each image as they can."
Doctors likely will end up reading digital mammograms on a monitor because they will not get the maximum value from looking exclusively at a hard copy but rather by examining multiple versions of the same image, she said. Other advantages of the new technology are that it is potentially more sensitive to photons coming from the X-ray source and that less extraneous "noise" is created. Digital pictures also will be easier to store, retrieve and transport, such as over the Internet.
Between 12 and 15 of the new digital devices are now being used around the world, she said. Fischer Imaging makes the machine UNC-CH owns. General Electric Medical Systems and Trex Medical Corp. also make them. Dr. Patricia Braeuning, assistant professor of radiology at UNC-CH, and dozens of other faculty, staff and students around the United States and Canada contributed to the research.
The National Cancer Institute chiefly sponsored the study, along with the Department of Defense, the U.S. Department of Health and Human Services' Office of Women's Health, the manufacturers, Eastman Kodak Corp. and Bayer Corp.
One strength of the independent study was that it used images not provided by the manufacturers, Pisano said. A limitation was that it measured the preferences of radiologists and not how well they performed in identifying breast cancer.
Note: To reach Pisano during the meeting, call her office assistant Anna
Cleveland at 919-966-1771. Beginning Dec. 4, the physician can be reached at
919-966-6957 or via email at etpisano@med.unc.edu
Contact: David Williamson, 919-962-8596.