This report originally appeared in the January 2011 issue of DOTmed Business News

By Trevor Bromley

Computer aided diagnostics (CAD) is widely used today by breast centers as a second look for radiologists to check for missed mammography detections. Mammography CAD systems have software algorithms that analyze mammograms for characteristics consistent with breast cancer. They mark suspicious spots for the radiologist to review. The radiologist first interprets the mammogram in the usual way, then looks at the CAD marks and decides whether to revise the interpretation based on CAD results. These systems typically find 85 percent to 90 percent of visible cancers which is more than a radiologist typically finds.
Today, CAD is close to being a standard of care and typically Medicare and other insurance companies reimburse for its cost. The use of CAD is likely to get a boost with the emphasis on preventative care in the new health care reform law. Additionally, since every woman over 40 in the U.S. is entitled to one free mammogram per year, there is an expectation that the market will grow. Wider acceptance will likely also come through improvements in CAD algorithms with higher sensitivity and lower false positive rates. Another important factor in the growth in use of CAD systems is that as mammography becomes increasingly digital, CAD use will increase because there are no films to digitize, resulting in lower cost and improved workflow.

Currently, there are three U.S. Food and Drug Administration-approved mammography CAD systems: R2 was the first (1998) and is a leader. They were subsequently sold to Hologic, manufacturer of a digital mammogram machine. R2 is now primarily sold for use with the Hologic Selenia system. The other player of consequence is iCAD. It’s sold with most other systems notably GE Healthcare. Carestream Health has an approved CAD product for film that has not gained much market acceptance.

Where CAD is going
Up until the last decade, all image processing was performed on expensive and powerful computers because it is so CPU intensive. However, with today's PCs offering the equivalent processing power of yesterday's supercomputers, the processing cost has decreased. As this trend continues, CAD systems will be able to utilize more powerful mathematical techniques to gain performance, which is expected to advance mostly through a steady reduction of CAD false positives.

Moreover, as the digital X-ray pictures improve, even to the point of having details of information the human eye cannot observe, it increases the likelihood of detecting cancer at an earlier stages. Early stage cancer is often overlooked by radiologists because normal structures in the vicinity may be much more prominent. This is particularly true for premenopausal women, who typically have denser breasts. Without CAD, radiologists routinely miss 20 percent to 40 percent of visible cancers. CAD has the potential to enable doctors to eliminate at least half of these false negatives.

Beyond breast: CAD for lung and colon
New applications are emerging, including approved CAD systems for breast ultrasound and breast MRI, as well as systems to find lung nodules in chest X-rays. Riverain Medical is the market leader for the latter application. Chest CT CAD systems are available, but the market is smaller because CT is not typically used for screening because of the risk associated with excessive radiation. Lower dose CT systems could open up this market in the future. There is CAD to find polyps for virtual colonoscopy, but this has been slow to emerge, because virtual colonoscopy is not yet widely accepted. Colonoscopies are performed for patients over 50, and many have polyps that must be snipped and biopsied, so in many cases, virtual must be followed by "real" colonoscopy to remove the polyps.

The future looks bright for this technology and with it, the health care options for millions of people will improve as well.

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