CAD May Result in Incomplete Image Observation

September 20, 2012

Using computer-aided detection software to help find target areas in images may result in readers missing areas not marked for viewing.

Using computer-aided detection (CAD) software to help find target areas in images may actually result in readers missing areas not marked for viewing, according to research published in the October issue of Academic Radiology.

Researchers performed two experiments as part of an eye-tracking study to determine eye movements as images were being read. Forty-seven observers with an average age of 24.3 years examined images for the targets, which were the letter “T.” Throughout the image, there were also several marks of the letter “L.”

The first experiment provided high noise and low similarity between the targets, meant to cause distraction and making the targets more difficult to locate. The second experiment used less distraction and provided more targets, making the targets easier to find.

Researchers found that although in the first experiment, observers were able to find many of the targets, guided by the CAD, this came at a cost: If targets were not in an area marked by the CAD, they were likely not located. For the second experiment, there was no noted behavioral benefit from CAD, but neither was there a cost in missed targets as there was in the first experiment.

In evaluating eye movements, the researchers saw that the CAD observers looked at a lower total area than did the non-CAD observers.

“CAD signals do not combine with observers' unaided performance in a straightforward manner,” concluded the authors. “CAD can engender a sense of certainty that can lead to incomplete search and elevated chances of missing unmarked stimuli.”