File compression can expand mammography's power

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A team of researchers at Purdue University has found that digitized mammograms are actually interpreted more accurately by radiologists once they have been "compressed" using techniques similar to those used to lessen the memory demand of images in digital cameras. Though compression strips away much of the original data, it still leaves intact those features that physicians need most to diagnose cancer effectively.

Once a mammogram has been converted into electronic form, it can contain more than 50 megabytes of data, which makes it prohibitively large for transmission by computer modem over a telephone line. Compounding the issue is that four such images are needed for a complete screening, and though it takes only a few minutes to obtain the x-ray pictures, getting a mammogram can be difficult. A 2001 FDA study showed that the number of mammography facilities has declined in most states, and the population of potential recipients of mammography services has increased. Telemedicine could potentially mitigate the problem.

On seven of nine measures of diagnostic accuracy, radiologists interpret the compressed images more accurately than they interpret the original images, even though the compressed images contain, on average, only 2 percent of the information in the originals.