ACRIN Study, Digital Era Spur Rise in Digital Mammography Facilities
The number of facilities in the United States offering digital mammography continues to grow at a rapid pace.
During the two-year period from January 2005 to January 2007, the percentage of accredited facilities or facilities undergoing accreditation with digital mammography equipment more than doubled (from 6.3 percent to 16.4 percent), according to national data from the Food and Drug Administration’s Mammography Quality Standards Act (MQSA).
The latest month for which figures are available, May 2007, show a significant jump even over January 2007, with 20.4 percent versus 16.4 percent of facilities respectively reporting digital mammography.
Carol H. Lee, M.D., chair of the ACR Commission on Breast Imaging, sees a two-fold push behind the rise in digital mammography.
The likely leading reason, she says, stems from the published results of the ACRIN (ACR Imaging Network) Digital Mammographic Screening Trial (DMIST), which showed that digital mammography detected significantly more cancers (up to 28 percent more) than screen-film mammography, in certain subsets of women.
The trial, published in the New England Journal of Medicine in October 2005, showed no difference between digital and screen-film mammography in detecting breast cancer for the general population of women. However, it did find that digital mammography detected more cancers in women who were 50 or younger, premenopausal and perimenopausal, or had dense breasts. Notably, digital mammography detects cancers in their early stages, when they are most treatable.
“That advantage spurred many facilities into acquiring digital equipment,” Dr. Lee says. “I am not surprised to see that this is happening.”
Mammography simply following other departments into digital era
Another reason for the growth, Dr. Lee says, is that the entire field of radiology is moving in the direction of digital. “Film is rapidly becoming less relevant in the rest of imaging,” she says. “We are in a digital era in imaging, and mammography is really the last area to go in that direction.”
“It’s amazing,” says Priscilla F. Butler, M.S., senior director of Breast Imaging Accreditation Programs at the ACR, “but when we’re talking totally digital it is not just the big academic institutions but little community hospitals as well.”
Butler noted that the October 2005 results of the ACRIN study did not result in an immediate jump in new US digital mammography installations. This is not surprising, she says, since the process of budgeting funds, ordering and delivering equipment can take months. However, there was a significant jump in the number of digital mammography units undergoing accreditation after May 2006, probably due to orders placed after the first Radiologic Society of North America Meeting (RSNA) following the ACRIN study. That study caused a buzz at the meeting and gave radiologists the opportunity to view digital equipment on the trade-show floor. Butler expects the number of facilities with digital mammography equipment to continue to rise as users become more familiar with the new technology.
Growth raises some concerns including need for breast radiologists
While the rise in the number of facilities with digital mammography capabilities is generally considered good news, it raises some concerns, Dr. Lee says.
Digital mammography equipment is more expensive than film equipment. Also, a number of studies have shown that it takes longer to interpret digital mammography than it does to interpret screen-film, Dr. Lee says. It can take extra time because digital allows users to make many more manipulations to improve image quality.
“There is a learning curve,” Dr. Lee says. “Radiologists will get faster as they go along, but the extra time to read digital images is significant enough to make a difference in workflow and workload.”
Workflow issues may be exacerbated by the growing need for radiologists who specialize in breast imaging. “Many of our profession are concerned about it because fewer people are entering the field of breast imaging,” Butler says. “They worry if there are enough qualified radiologists out there who are going to be able to do this work and provide timely reporting of these images.”
Reimbursement could be a factor as well in availability of digital facilities
Reimbursement is also an issue. “Reimbursement is very variable right now,” Butler says. Medicare and some private payers will reimburse more for the technical component for digital but not for the professional component. Some radiology residents are already reluctant to enter breast imaging because it is a highly litigious area and reimbursements are lower.
“We have to keep these factors in mind and not create situations where people are more reluctant to go into breast imaging,” Butler says. With fewer radiologists to interpret digital exams, “standard of care could become an issue and is something that we need to address.”
DMIST was one of the largest breast cancer screening studies ever performed. Starting in Oct. 2001, it enrolled 49,528 women at 33 sites in the United States and Canada who had no signs of breast cancer. Women in the trial were given both digital and screen-film mammograms. Two different radiologists independently interpreted the mammograms. The cancer status of DMIST participants was determined through available breast biopsy information within 15 months of study entry or through follow-up mammography 10 months or later after study entry.
