Studies Find X-Rays Just as Accurate as Digital Mammography

By M.L. Baker  |  Posted 06-15-2005
Three studies on several thousand women have demonstrated that X-ray images are just as accurate as so-called digital mammograms, in which high-tech equipment records images electronically.

Digital mammography systems, which were first approved for marketing in the United States in 2000, cost at least three times as much as film systems, according to ECRI, the nonprofit health services research agency that conducted the report. But the technology does offer some advantages over X-ray film: The images are stored directly in a computer system, which allows them to be digitally enhanced, magnified or distributed. Hassles of storing, processing and handling film are eliminated. In some cases, digital mammography requires slightly lower doses of radiation.

"Cost-effectiveness will ultimately determine whether full-field digital mammography technology is adopted, since hospitals must justify their purchase based on exam volume and patient population," the report concluded.

The assessment is not the last word. The National Cancer Institute sponsored another new clinical study, enrolling 49,500 women in the United States and Canada. Each patient received both traditional and digital mammograms, with follow-up exams after one year.

An analysis of that study is expected soon, but Robert Maliff, associate director of the Health Systems Group at ECRI, said he expected digital mammography to show only an incremental improvement, if anything. However, if doctors become convinced that digital images can be read just as accurately as X-rays, operational efficiencies might persuade institutions that do many mammograms to move toward the high-tech option. Maliff also predicted that some hospitals might adopt the technology for marketing reasons.

A separate study, reported in HealthDay, did find a factor that predicted more accurate diagnosis of mammograms: Doctors with 25 years of experience who read more than 2,500 mammograms each year are 30 percent better at finding cancerous tumors than doctors who read less than 800 a year. Detection rates for individual doctors ranged from 29 percent to 97 percent when cancers were present. Individual doctors falsely identified cancer in 1 percent to 29 percent of the mammograms they evaluated for the study.

The ECRI report was summarized by the Center for the Advancement of Health.