FDA to release clinical protocolfor full-view digital mammography

Agency still undecided on 510(k) vs. PMA issue

The Food and Drug Administration is attempting to clarify theregulatory status of full-view digital mammography by releasinga draft protocol that it expects vendors to use to receive clearancefor marketing the devices in the U.S. The FDA has not yet decidedwhether it will require vendors to submit a 510(k) applicationor a more rigorous premarket approval (PMA) application, however.

An FDA official familiar with regulatory review disclosed latelast month that a draft clinical protocol that will guide full-viewdigital device testing will be released this month. That protocolwill be sent to the imaging industry news media as well as tothe National Electrical Manufacturers Association for disseminationto vendors. The FDA will receive public comment on the proposalbefore issuing final rules.

Details of the FDA's plan may change before the protocol'srelease, but in its current form it could allow vendors to avoidthe cumbersome PMA process, which might add years to the commercializationcycle of full-view digital systems. The FDA hinted last year thatit was leaning toward the PMA route (SCAN 1/18/95).

The FDA official indicated that the agency has not yet decidedwhether to require vendors to submit a 510(k) application or aPMA filing for full-view digital. Until it does, it is possiblethat the agency will accept a high-quality 510(k) that is backedby clinical data, the official said.

The clinical protocol to be released this month will serveas a cookbook for vendors undertaking studies to demonstrate safetyand clinical efficacy. A key remaining question centers aroundhow many patients will have to be included in the studies. Thefinal sample size may be around 300 patients, the official said.

Even if a more relaxed protocol is allowed, it will not givevendors carte blanche to market full-view digital systems. Accordingto the official, the initial round of FDA clearances will limitthe use of all-digital devices to diagnostic breast imaging applications.This procedural category includes follow-up imaging to investigatesuspicious masses identified with screening mammography.

Far more research must be completed before the FDA can judgewhether full-view digital mammography is appropriate for screeningapplications, the official said. That determination will probablybe made through an FDA-sponsored, postmarket surveillance programinvolving tens of thousands of women, he said.

The official noted that postmarket surveillance will requirecooperation among manufacturers to establish an installed baseof full-view digital systems large enough to conduct the test.If the FDA requires postmarket surveillance, a final ruling onfull-view digital mammography for screening applications is severalyears away.

The disclosures are a mixed blessing for vendors primed tointroduce full-view digital breast imaging. They offer the hopethat the first round of approvals for diagnostic applicationsmay begin in 1996. The long research cycle for screening applicationsmeans the bulk of the U.S. market will be out of bounds untiltesting is completed.

Still, at least three manufacturers are at the gate in therace to popularize digital breast imaging. Bennett X-Ray of Copiague,NY, will begin shipping its full-view digital mammography systemon a regular basis to European and Asian customers in the nexttwo months, according to CEO Calvin Kleinman.

Fischer Imaging of Denver is about six months away from applyingfor regulatory clearance, if digital mammography qualifies forreview through the 510(k) process, according to chairman and CEOMorgan Nields.

Nields envisions a bureaucratic nightmare for manufacturersif PMAs are required. Numerous design changes always follow theintroduction of a new technology, he noted. That would force Fischerto file numerous PMA amendments and perhaps repeat clinical studiesto examine the effect of design changes, he said.

"If they say we need a PMA, we're probably going to slowdown and make sure many of those improvements are made beforewe do the studies," Nields said.

Lorad of Danbury, CT, is also in the race to commercializethe first full-view digital imager. The company has displayedits work on the technology at the last two Radiological Societyof North America conferences. Clinical trials are under way atthe University of California at San Diego, and University of Virginiaresearchers will soon receive an investigational system, accordingto president Hal Kirshner.