BY DEBORAH R. DAKINS

Development of full-field digital mammography and computer-aided detection has occurred on separate, but parallel, tracks. Industry observers predict that CAD will become a standard feature of digital workstations, and the commercial pairing of CAD with FFDM in one device is expected to give both technologies a boost.

But first digital mammography has to leap a critical hurdle. Several vendors are in various stages of device testing or approval by the FDA. More serious is the challenge of marketing equipment that has yet to show a clear-cut clinical edge over its conventional counterpart.

"If you look at the beginnings of any of the digital modalities, first-generation products didn"t realize all of the ultimate potential," said Don Blomstrom, national sales manager for mammography at Instrumentarium. "Developing the digital mammography machine is the easy part. It"s the presentation and management of that information once it is acquired that"s hard. Digital makes a lot of sense, but so far we haven"t made mammography any faster for the radiologist. We have made it a whole lot more expensive."

Blomstrom believes that the challenges facing digital mammography will be met, but it will take time and increased R&D. Help may come from the trial being conducted under the auspices of the American College of Radiology Imaging Network (see main story).

Vendors won"t be waiting for those results, due in 2004. GE already has its Senographe 2000D FDA-approved and in use. Others are not far behind.

In late July, Fischer Imaging received an approvable letter from the FDA for its SenoScan FFDM system. In May, Hologic submitted its premarket approval application to the FDA for its Lorad device. Fuji is in the testing phases of its computed radiography for mammography system. And Instrumentarium is in the early clinical testing phase of its Diamond digital mammography unit.

Digital may hold numerous advantages over screen-film mammography: quick image access, efficient organization of double-reads, the option for telemammography and CAD, and avoidance of film costs. But the devices have lingering technical limitations. Several vendors agree that the current crop of digital mammography devices?including those still in testing?will rapidly be eclipsed by the next generation of equipment.

"The devices that are now or will soon be available incorporate any number of trade-offs and compromises," said Roman Janer, vice president of Lorad"s digital imaging program. "The next generation of equipment, which relies on amorphous selenium receptors, will offer much better performance, due to direct conversion technology."

Such improved performance will have a direct impact on the ability to use digital machines for diagnostic purposes?such as digital subtraction angiography studies of breast vasculature that are less invasive that the current method, he said.

The Lorad system undergoing PMA review by the FDA uses charge-coupled device technology, Janer said, but the company is already working on next-stage equipment that will incorporate selenium plates. It"s a direction other companies are also taking.

"Selenium (receptors) will be a second-generation enhancement," said Blomstrom of Instrumentarium. "Kodak is using it, Siemens has announced that it will be using it, and Lorad is using it. So with that percentage of the marketplace moving in the same direction, it"s safe to say that selenium is going to be the de facto standard in a couple of years."