Since full-field mammography started going digital eight years ago, systems based on flat-panel arrays have dominated. But computed radiography has begun seeping into that market and, if the FDA allows CR companies to apply for streamlined 510(k) approval of mammography upgrades, the trickle of CR products could turn into a flood.
With the appearance of CR-based full-field digital mammography products, mammographers can choose whether to ease into digital by extending the life cycle of already installed equipment or invest in flat-panel systems as the bridge to a 3D future.
FLAT PANEL'S EDGE
Until lately, flat-panel mammography systems have been the only game in town. A little over 40% of the 13,000-plus Mammography Quality Standardization Act-accredited facilities currently have FFDM systems, and most are built around solid-state electronics, sometimes referred to as being based in digital radiography.
The only company to have an FDAapproved CR mammography system, Fujifilm Medical Systems USA, has sold 500 Fuji CR for mammography (FCRm) units in the U.S. since the product was launched in 2006. Flat-panel systems have been popular because they are highly efficient. They allow imaging centers to get more patients through screening in less time. The Mammomat Inspiration Siemens Medical Solutions requires only 27 seconds between exposure times and 18 seconds between the exposure and display of digital images. The Inspiration can therefore examine more than 15 patients an hour.
CR mammography has trouble competing in terms of throughput. "With CR, you still have the interaction with the technologist, as far as handling cassettes," said Pat Montgomery, manager of women's health for Agfa HealthCare, a maker of CR products. "The cassettes are digital as opposed to having film , but the technologist still has to put a cassette into a CR reader, wait for processing, then take it out. If a mammography site has high volume or a patient backlog [and] would benefit by getting more patients through, it probably would want to consider DR."
DR systems also lend themselves to advanced applications. They bring high image quality at low doses, so the technology has the potential to obtain sequenced images that can be combined and reconstructed into a 3D data set. CR does not have that potential, said Jose Martinez Abellan, marketing manager for GE Healthcare's mammography business, a maker of flat-panel FFDM systems. A downside of DR is cost.
Although the price tag for DR-based systems has declined steadily since 2000, it may not be enough. DR manufacturers are beginning to offer economical versions of their products. Hologic's Selenia S, which is targeted at freestanding clinics and the mobile market, has fewer bells and whistles than the full-blown Selenia system and is more competitively priced against CR systems than full-feature solid-state FFDM products, yet the price differential remains an issue.
Flat-panel DR-based FFDM products typically cost around $350,000, while CR-based units run between $140,000 and $240,000. So while some facilities may opt for DR in their principal screening center, they could find CR more appealing, price-wise, for remote locations, said Stephen Archer, director of worldwide marketing for mammography solutions at Carestream Health, which—like Agfa—is developing a CR-based FFDM for sale in the U.S.
THE CR ALTERNATIVE
Manufacturers, such as Carestream, Fuji, and Agfa, that sell CR mammography products outside the U.S. appear poised to effect a swift introduction of their products into this country, now that the FDA is actively considering downgrading CR mammography to a class of device that requires less rigorous approval. The FDA closed the public comment period concerning a possible switch from premarket approval to 510(k) status for CR mammography at the end of August. A decision on when and how to reclassify FFDM is expected in the coming months.
If the FDA does make the change, which may not happen until late winter or early spring, CR companies will be able to sell in the U.S. the exact same mammography upgrades they market elsewhere. Agfa sells mammography add-ons to its CR 85-X multiplate and CR 35-X singleplate readers throughout the world. Carestream Health offers the DirectView CR 975, which can process up to eight plates at once, and two single-plate options: the Elite and the Classic, which differ in speed and price. And Konica Minolta markets the Regius Xpress CR.
CR manufacturers base their hopes of gaining a wider presence in mammography not only on their lower price points. They also stress that CR offers an easy digital conversion.
"There is no disruption of workflow going from film to CR," said Jeanine Rader, director of women's healthcare for Fujifilm. "Technologists do the same thing they did before.
And there is no need to take walls down or make changes to accommodate new flat-panel technology."
CR also fits right in with existing analog technology.
"If a facility has been doing screen-film mammography and they have an x-ray generator that is reasonably modern or that they don't want to replace, maybe because of cost, CR works very well," Archer said.
A CHALLENGING WORKFLOW
Despite the differences, DR and CR have one challenge in common: how to manage images from other modalities and different PACS and RIS vendors.
GE Healthcare has obtained FDA approval to sell a mammography workflow solution from Image Diagnost International, a German software company it recently acquired. The product, which will be formally launched at the RSNA meeting, can be used by imaging centers of all sizes that do not have a high volume of screening studies but nevertheless have workflow problems and by academic medical centers that conduct research on tomosynthesis or other imaging devices.
"The company has developed workflow solutions in screening," Abellan said. "It has built all the interfaces for use with multiple PACS and RIS vendors. It has done a huge amount of work on how to relate previous images to current images and on how to do all the work, from entering the patient into the HIS/RIS to doing the diagnosis on the workstation."
Konica Minolta has developed a distributed, rather than centralized, workflow plan around the CR-based system the company markets outside the U.S. and hopes to bring it to this country in the months ahead. It eliminates the need to move from the exam room to the central processor and wait for processing.
Agfa and Fuji are offering vendor-neutral multimodality diagnostic review stations. Fuji's Synapse 3.2.1 workstation is not limited by modality. It not only handles the screen-ing images that come from digital detectors, but also displays MR, ultrasound, and CT images of the breast.
Agfa's Impax MA3000 diagnostic workstation links digital mammography with other forms of breast imaging as well as chest x-rays, PET scans, and any other images on a PACS network.
"Radiologists can sit down and do all of their work from one location versus having to move from workstation to workstation," Montgomery said. "This will translate into benefits for patient care because the point is to make the radiologist more efficient."
ENTER TOMOSYNTHESIS
A nagging question for the evolving digital mammography market involves tomosynthesis, a technology dependent on flat-panel detectors that deliver volumetric images of the breast that cannot be generated with CR. Tomosynthesis promises greater sensitivity and specificity in detecting breast cancers at lower doses and with less compression.
"There is the possibility that one tomo view would replace two regular views on mammography, and that means half the dose of a regular mammogram," said Jonny Eser, product manager for women's health at Siemens Medical Solutions. "And by slicing through the breast with tomosynthesis, you should be able to see lesions without compressing the breast to find masses that hide under the glandular tissue."
The relevance of tomosynthesis depends, however, on its commercialization. Hologic, the only firm so far to submit data to the FDA for approval of a tomosynthesis unit, has been fielding requests from reviewers for clarification of the data. The company nevertheless expects to begin marketing the product at the beginning of 2009. Hologic has already launched tomosynthesis in Europe and will begin shipping units in December, according to CEO Jack Cumming.
Even after its entry into the U.S., widespread adoption of tomosynthesis will take time. The technology most likely will be used mostly in research settings and by academic medical centers initially, until the procedure is widely reimbursed. Whether and when this happens may depend on research to establish if tomosynthesis will complement or replace fullfield mammography. The practical use of the technology also depends on vendors finding ways to manage its volumetric images. Tomosynthesis developers are testing prototype workstations.
"With tomosynthesis, you have to address 30 times the quantity of data you get today, and time is critical," said David Caumartin, general manager of global mammography for GE Healthcare. "If you need more time to review the tomosynthesis images, then you need more radiologists, which we will not get. So we are working on ways to handle this huge amount of information."
