Digital mammography nears milestone as obstacles fade

About 90 digital mammography systems were shipped to U.S. customers in the first half of 2004, compared with 130 film-based units, according to industry executive estimates. Full-field digital mammography systems thus accounted for almost 40% of the units delivered in the first half of last year. The percentage of revenue tips the scales in FFDM's favor, as each digital system sells for more than a half-million dollars, about six times more than the cost of a film system.

Industry estimates peg the 2004 first-half revenues for FFDM at $55 million. This compares with estimates of only about $11 million in revenue for conventional mammography systems.

The ratio of sales between film-based units and FFDM systems is continuing to shift in favor of digital products. Booked orders of FFDM systems are running about 20% ahead of sales, indicating healthy growth in demand. Meanwhile, sales of analog equipment are plummeting. If the second half is no better than the first, analog mammography sales will have dropped by about 40% from last year's numbers. If FFDM sales remain on track from the first half of 2004, digital mammography will jump to $110 million in revenues compared with $70 million in 2003-a 57% increase.

It's been a long haul for digital mammography, which was first approved by the FDA for use in the U.S. five years ago this month. The modality has been challenged by high costs, regulatory fits and starts, and the perennial problems-malpractice suits and low reimbursement chief among them-that have always plagued mammography. But the figures above gathered by Diagnostic Imaging business editor Greg Freiherr suggest that digital mammography has turned the corner. Sometime this year, digital unit sales will probably exceed film unit sales.

This is good news for women who undergo screening or diagnostic mammography. The digital systems produce lower radiation dose and, generally, lower recall rates. Faster throughput with digital mammography permits better scheduling and reduces waiting time. Sophisticated algorithms that process the digital data will eventually allow radiologists to rapidly focus on specific findings, such as calcifications or masses. Digital is also more easily integrated with a CAD review program than film.

Unfortunately, digital mammography has so far failed to improve cancer detection rates over those achieved with film. In addition, reading times have tended to be a bit longer with digital than they are with film. Part of the problem lies in workstation design that has yet to master the digital mammography environment, requiring too much effort to achieve the benefits. Digital mammography also suffers from other problems: Large data files create storage and transmission hassles, and the need to refer to priors, which are often on film, interferes with optimal reading room and workflow setup.

But all of these problems can be solved, and they are being addressed. In the meantime, it's clear that the market is willing to overlook these shortcomings and is pushing the modality forward. As that happens, we'll begin to see improvements in accuracy associated with digital mammography. Workstations will continue to improve, and storage issues will be resolved. Priors increasingly will be available in a digital format.

Also on the horizon are developments that take digital a step further. As our cover story notes, advanced applications such as contrast mammography and breast tomosynthesis are facilitated by a digital environment.

For a long time, mammography has been the last holdout in the shift to an all-digital environment. That's still the case in many instances, but the barriers to adoption are falling rapidly.