Digital mammography systems are striving to differentiate themselves in image quality, easy integration with CAD and the ability to more efficiently review and manage images digitally - and clinicians and market watchers hope the Digital Mammographic Imaging Screening Trial (DMIST) of 50,000 women at 35 sites will bring some answers when results are released next spring. In the meantime, a variety of facilities are successfully transitioning to digital mammography.
Full-field digital mammography (FFDM) came on the scene in 2000 with promises of better images, reduced radiation dose, boosts in productivity and more efficient image management. GE was first with its Senographe 2000D; Fischer and Hologic followed with SenoScan and Selenia respectively - with the combined market penetration of three vendors hovering between 5 and 10 percent. Siemens Medical Solutions is the newest to market with its Mammomat Novation gaining its PMA in August. (See "New Systems Crowd the Market," Page 30.) New digital mammography options from PlanMed and Sectra, and a CR-based mammography system from Fujifilm Medical Systems, are in the works and are expected to hit the market in the next year.
|Taking Digital Mammo on the Road|
One of the appeals of digital mammography is its ability to facilitate remote mammography and place screening units in locations without an on-site radiologist. Mary M. Kelly, MD, medical director of imaging at the Providence Campus Comprehensive Breast Center of the Swedish Cancer Institute (Seattle), says, "Digital is a natural for mobile."
Swedish Cancer Institute has four mobile mammography units. Two vans are used to transport analog systems, which entails wheeling the machine onto the van and into a facility that might have a questionable power source. Techs rely on a portable dark room and lug a suitcase back to the center each day for development. "There are a lot of logistical problems, and it's labor intensive," Kelly confirms.
This spring, the center equipped an 18-wheel tractor-trailer truck with a Hologic Selenia FFDM system. Kelly explains, "The lack of film and film halters allows us to preserve the integrity of the images. It's also ideal from a QA and QC point of view. Instead of moving the equipment, we bring a generator, and the patient comes on board. This is great logistically and it minimizes artifacts."
Eventually, mobile images will be sent back to the breast center for online reading via a satellite. Kelly says, "This hasn't been done before. We plan on videoconferencing with the tech and looking at the images within 15 minutes of the exam and doing additional views on the spot as necessary. Hopefully, we'll be able to provide women with immediate results."
Despite all of the market action, digital mammography has not yet established its superiority over conventional analog products. But a more firm answer is expected next spring after researchers evaluate the results of the Digital Mammographic Imaging Screening Trial (DMIST), a comparison of digital and film mammography in nearly 50,000 women conducted at 35 clinical sites in the U.S. and Canada. "We believe this study will be powerful enough to tell if digital mammography is better, the same or worse than conventional mammography in an average risk population," says Etta D. Pisano, MD, DMIST principal investigator and professor of radiology and chief of breast imaging at the University of North Carolina School of Medicine at Chapel Hill.
Pisano says if the diagnostic accuracy of digital and conventional mammography proves to be the same, digital mammography may be justified if it can reduce the number of false positives or costs. As the DMIST trial winds down, sites that have implemented digital mammography are finding:
- An improved ability to resolve calcifications, which translates into reductions in the recall rate for calcifications.
- Streamlined CAD processes via the direct integration of CAD technology.
- The pluses of the digital environment: the ability to store and transfer images digitally.
- A hefty learning curve within mammography that can include workflow challenges and slight increases in the callback rate. FFDM sites do predict productivity gains after the transition to digital is complete.
- A need for a streamlined workstation to help integrate analog and digital technology, other breast imaging modalities and PACS.
THE DIGITAL EXPERIENCE
The transition from analog to digital mammography typically requires a somewhat lengthy learning