Dell's Axim PDA and Apple's iPod Touch hold up well against off-the-shelf monitors for reading some CT images, according to a paper in the February issue of American Journal of Roentgenology.

In the study, radiologists were just as good, and sometimes slightly better, at identifying wrist or brain injuries on CT slices using the handheld devices as they were with so-called secondary-class monitors.

This suggests handhelds might have a useful clinical role. Secondary-class monitors, off-the-shelf monitors that do not meet the more demanding specifications for primary diagnoses by radiologists, are common in many parts of the hospital, such as emergency rooms, according to Rachel Toomey, lead author of the study and a researcher at the University College Dublin School of Medicine in Dublin, Ireland. She notes treatment decisions are often based on them.
"For instance, clinicians in emergency departments, clinics and intensive care units might all view radiological images on standard, off-the-shelf displays," she tells DOTmed News by email.

HOW THE STUDY WAS DONE

In the study, conducted during American Board of Radiology examinations in Louisville, Kentucky, board-certified radiologists examined 30 CT wrist and 30 brain images, with about half the slices showing lesions. Forty-nine rads had to make "diagnoses" on the images on both PDA and monitors, while 35 rads had to use the iPod Touch and monitors.

The physicians' readings on handheld devices and monitors were almost equally accurate, with some rads using the Dell PDA slightly better at finding or ruling out lesions on the brain CT slices than with the monitors. No significant difference was found on readings between monitors and iPods in the trials.

Toomey doesn't know why some of the results were significantly better with the PDA and not the iPod, but she suspects it has something to do with the lighting of the screen and the better resolution of the PDA, at least on the initial view. Although radiologists could zoom in on images displayed on the iPod Touch, the first view is set at a lower resolution, and some doctors might have chosen not to enlarge the pictures.

IS SMALLER BETTER?

While no one knows for sure, some scientists have suggested that smaller images might actually improve diagnostic accuracy. And all for a curious reason: the fovea-to-image ratio.

Because our vision is sharpest for objects presented to a very small area, around the foveal region of the retina, showing the whole image on a smaller screen might allow more of it to fall on that region of the eye, thus giving viewers more spatial detail, Toomey explains.

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