Abstract
The aim of this study was to investigate where neurologists look when they view brain computed tomography (CT) images and to evaluate how they deploy their visual attention by comparing their gaze distribution with saliency maps. Brain CT images showing cerebrovascular accidents were presented to 12 neurologists and 12 control subjects. The subjects' ocular fixation positions were recorded using an eye-tracking device (Eyelink 1000). Heat maps were created based on the eye-fixation patterns of each group and compared between the two groups. The heat maps revealed that the areas on which control subjects frequently fixated often coincided with areas identified as outstanding in saliency maps, while the areas on which neurologists frequently fixated often did not. Dwell time in regions of interest (ROI) was likewise compared between the two groups, revealing that, although dwell time on large lesions was not different between the two groups, dwell time in clinically important areas with low salience was longer in neurologists than in controls. Therefore it appears that neurologists intentionally scan clinically important areas when reading brain CT images showing cerebrovascular accidents. Both neurologists and control subjects used the “bottom-up salience” form of visual attention, although the neurologists more effectively used the “top-down instruction” form.
Highlights
In clinical practice, neurologists often use brain computed tomography (CT) images to detect lesions in patients
We showed that neurologists and controls differ in the way they view brain CT images, our controls had some knowledge about the brain
This study revealed the following findings: in image 2, both neurologists and controls gazed at high-salience areas such as the large hemorrhagic area
Summary
Neurologists often use brain computed tomography (CT) images to detect lesions in patients. Bottom-up salience indicates that attention is captured by a visually conspicuous object, irrespective of the subject’s intention. These two information-processing mechanisms usually overlap each other [1]. We used an eye-tracking device to investigate the patterns of visual attention involved in searching for lesions in brain CT images. This device allows us to create heat maps, a means of objectively visualizing the distribution of a subject’s gaze over an image [5]. We can determine the type or types of visual attention taking place in the brain by comparing our eye-tracking data with saliency maps of the CT images
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