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May 2, 2005

CR Mammography
By Dan Harvey
Radiology Today
Vol. 6 No. 9 P. 12

When its anticipated FDA approval comes through, computed radiography may speed the expansion of digital mammography.

As the imaging field inexorably moves into the digital age, mammography lingers behind.

However, that could change soon, depending on how fast the FDA acts on approving a computed radiography (CR) system for mammography. It’s hard to nail down a date when it comes to FDA approval, but when it comes to CR, technology may push mammography into the digital age. “It will spur the whole digital transformation, similar to what happened in general radiography,” says Helen Titus, worldwide marketing manager for digital capture solutions at Kodak Health Imaging Group in Rochester, N.Y.

The main factors driving the move toward CR mammography are cost-effectiveness, retrofit potentials, and flexibility. But cost is probably the biggest factor. “CR is simply a more cost-effective solution than something like full-field direct radiography [DR],” Titus points out. “The system’s costs are less expensive to the end user.”

Beyond those considerations, CR can provide a smoother transition into digital mammography for many facilities seeking to take the first step into digital territory.

Flying Under the Radar
Recently, DR has pushed aside CR in the imaging community consciousness, perhaps due to the hype surrounding flat-panel direct radiology technology. In the United States at least, much has been made about the benefits of flat-panel full-field digital mammography (FFDM) in the last several years. But many observers believe CR mammography offers the same technological advantages as FFDM, but at a lesser cost.

Both provide faster image acquisition, increased efficiency, reduced exam time, increased throughput, and elimination of film.

For smaller facilities with lower imaging volume, throughput advantages mean little. Faster is not necessarily better without having enough patient volume to make a difference. The economic analysis of digital mammography generally requires a high volume of cases to offset the cost.

Implementing CR can be as simple a matter as replacing analog cassettes with digital ones. Also, a single CR unit can handle up to four x-ray rooms. Conversely, with DR, the entire x-ray room needs to be changed, and DR devices can be used only for one room.

Retrofitting for the Future
The potential to retrofit to existing technology is another significant advantage. “Manufacturers may be able to supply a retrofit to those systems already in use for general radiography or other imaging purposes,” Titus points out. That ties right into the cost advantage. “CR is a digital technology, too, but it is just done differently,” reminds Andy Vandergrift, national program manager for women’s healthcare imaging for Fujifilm Medical Systems USA, Inc., the Stamford, Conn.-based company that is a major player in CR technology and has several CR mammography solutions awaiting FDA approval. “The big difference is the removable detector, which is the major cost advantage of CR mammography.”

The removable cassette enables a facility to use its existing mammography unit—unlike with flat-panel FFDM, where a vendor would have to replace the whole unit. “Facilities like that idea because they’ve chosen the existing devices for specific reasons and technologists are comfortable with those devices. They can just continue using those in the CR world,” Vandergrift says.

That comfort level represents another potential advantage—the smooth transition into the digital world that CR can provide. “We all know about how change can be a problem, but CR digital technology would have the least impact on the technologist,” Vandergrift says.

Once installed, CR technology can be used for other general radiography purposes. It need not be dedicated to just mammography. Titus cites the example of European imaging facilities that have been using CR mammography for at least a decade. “In certain environments, particularly in Europe, there are no dedicated facilities for mammography,” she says. “General radiography imaging is done in the same facility. So you have a piece of CR equipment that is used for multiple purposes.” The CR system’s flexibility could enable a facility to transition to an all-digital environment. “It offers more choices in the facility,” she says.

At the CR Vanguard
Back in the early 1980s, Fuji pioneered the use of CR technology. It introduced its first CR for mammography product in 1983, and it was used in the United States. (At the time, it used 100-micron pixel spot size.) Later, in the 1990s, the FDA reclassified CR for mammography as a Class III device. Fuji didn’t immediately seek reapproval because it was working on some new innovations that would require another approval process. Also in the 1990s, other companies entered the market, offering smaller and less expensive CR systems. “We recognized that newer technology was necessary for us to be competitive,” recalls Vandergrift.

Around the same time, the digital marketplace started to undergo a change as vendors began promoting flat-panel DR as a more effective alternative. The CR mammography narrative stalled as Fuji continued working on its new developments. CR matured as a technology, and Fuji introduced the current 50-micron resolution as well as dual-side reading.

“I think those two ingredients actually differentiate us from other CR vendors and allow us to be competitive with flat panel vendors in the marketplace today,” Vandergrift says.

In the meantime, Fuji had developed the ClearView-CS for general radiography that could be upgraded for mammography (ClearView-CSM). It was widely adopted in Asia and Europe, but it wasn’t introduced until 2003 in the United States, where it could be used only for general radiography. Vandergrift says the Fuji unit has become the most widely adopted digital mammography technology in the world, and it has been installed in more than 2,000 sites in Europe, Asia, and Australia.

When CR for mammography is approved by the FDA, which Fuji expects to happen by mid to late summer, Vandergrift anticipates that it will experience rapid adoption. The reasons are the improved image quality resulting from the 50-micron spatial resolution and its cost-effectiveness. Fuji offerings will also include computer-aided detection (CAD) and PACS for mammography. “In other parts of the world, we’ve been out there for about a year and a half,” Vandergrift says. “Because we have such a large user base already in CR mammography and because this new technology was adopted so rapidly, we believe a similar type of adoption may happen in the United States.”

Waiting in the Wings
When FDA approval does come, Fuji has ready its FCRm unit equipped with a four-cassette, multiplate reader called the ClearView-CSM. “First, images are acquired on an imaging plate that resides inside a cassette,” explains Vandergrift. “That cassette is then carried over to the ClearView-CSM.”

The ClearView reader features dual-side reading technology that enables simultaneous reading of both sides of the plate. According to the company, this offers 100% higher detective quantum efficiency and lower noise compared with film screen mammography. In addition, it has 50-micron pixel sampling, and it enables processing of up to 20 exams per hour in as many as four exam rooms.

In addition, like the flat-panel vendors, Fuji has a technologist’s console (the IITN, an image and information processor). “When the image is read, it is displayed on the console and the technologists perform the QC,” says Vandergrift. “They’d look at it for penetration and positioning, and then it would be made available for the radiologist.”

The ClearView reader is compatible with existing mammography imaging units, requiring only the analog film cassettes to be replaced with CR cassettes. This enables a facility to easily transition its mammography department to digital with a fraction of the expense associated with FFDM.

ClearView also provides general radiography capabilities. It can read conventional imaging plates at a rate of more than 100 per hour. As such, many customers don’t have to buy separate mammography and general CR readers. Vandergrift stresses that this is an important point, particularly for smaller imaging centers. “The financial impact may be too great for them to adopt digital mammography, but our reader can also be used for general x-ray,” he says. “In facilities with one or two mammography rooms and a general x-ray room, the user simply gets another type of cassette and imaging plate and uses the very same reader.” Thus, a ClearView installation can allow an imaging center to become entirely digital.

Vandergrift also emphasizes that this is not new technology. It is mature technology that has served the international markets well. Moreover, in initial clinical trials in the United States, researchers using FCRm could better visualize abnormalities in women with dense breasts. It’s also significant to note that the FCRm was used in the large-scale Digital Mammographic Imaging Screening Trial. Researchers used it to acquire many of the study’s images. “We were responsible for about 10,000 of 50,000 patients,” Vandergrift says. “So, we were the second [largest] product involved in the trial.”

Looking Ahead
Many facilities have already purchased the reader for general x-ray, Vandergrift points out. Now, they are awaiting FDA approval for CR mammography. Then it will be a simple matter to upgrade the existing hardware for mammography.

Other Fuji CR mammography offerings include the MV-SR 657, a mammography viewing station that features Fuji’s own CAD software and tools such as magnification control, window and level, panning, previous study recall, and selectable display features. It will also offer advanced image processing options such as structured pattern reconstruction, multifrequency processing, and pattern enhancement for mammography, which detects and improves the conspicuity of microcalcifications.

Fuji’s Synapse Multi-modality Breast Imaging Workstation was designed for facilities performing FFDM, breast MR, and ultrasound. It provides the functionality of Fuji’s Synapse PACS. “We have the advantage of being a PACS vendor, too,” says Vandergrift, “so this workstation offers all of the benefits of PACS. A radiologist can view CR mammography, other full-field vendor images, as well as MR and breast ultrasound…”

The Synapse configuration can also be used as a full-featured diagnostic workstation for any imaging exam, providing additional workflow improvements. The workstation includes dual, high-brightness, 5-megapixel flat-panel monitors for softcopy diagnosis and an optional third 20-inch color liquid crystal display monitor for productivity applications and viewing of color images. When coupled with FCRm, the workstation can be used by the radiologist to communicate via notes or audio clips with a technologist at the Fuji’s FCRm IIP technologist console. This can take place within the same site or between separate sites.

Kodak Offering Coming
Kodak has been in the digital mammography marketplace outside the United States for years. Kodak currently sells mammography cassettes that are used in CR systems.

Like Fuji, Kodak awaits FDA approval. The company has been working on upgrading mammographic applications—including screens and cassettes—to improve mammography images acquired on the Kodak DirectView CR 850 and CR 950 CR systems. Its DirectView PACS System 5 Mammography upgrade allows efficient image review and storage for FFDM systems and other digital modalities used in mammography, as well as MRI and ultrasound. The upgrade includes a mammography workstation that features two 5-megapixel monitors and supports imaging modalities from multiple vendors.

FFDM works well, but cost considerations held it back in the marketplace. Many people in radiology believe it will light the fuse for a CR explosion in mammography because it offers the same benefits as DR and is more cost-effective.

“All facilities—large or small—have capital investment restrictions, and CR allows [them] into the digital world without having to purchase the more expensive, full-field solutions,” says Titus.

According to Vandergrift, roughly 10% of accredited facilities are using FFDM, which has been available for approximately five years. “There are obvious reasons for that,” he says. “Customers haven’t bought into existing solutions. But we believe that once CR mammography is available, it will bring digital mammography into the market in a much bigger way.”

— Dan Harvey is a freelance writer based in Wilmington, Del. He is a frequent contributor to Radiology Today.

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