Thin-section CT of the lungs: eye-tracking analysis of the visual approach to reading tiled and stacked display formats

Abstract

Objective: To use eye-tracking analysis to identify the differences in approach to and efficiency of reading thin-section CT of the lungs presented tiled and stacked soft-copy displays.

Materials and methods: Four chest radiologists read 16 thin-section CT examinations displayed in either a tiled (four images at once) or stacked (full screen cine) format. Eye-movements were recorded and analysed in terms of movement type; saccade distance (classified by the calculated range of useful peripheral vision), number of fixations, duration and direction of gaze-comparison of the areas of the images viewed.

Results: Cases presented in stacked format were read quicker than when presented in tiled format with a greater fixation frequency (5 fixations versus 4.5 fixations points per 100 data points; p<0.001) and a greater proportion of short saccades (97% versus 94%; p<0.005). The consistency with which the observers viewed equivalent areas of the scan images in different cases was greater when viewing in stacked format (mean kappa 0.45 versus 0.36; p<0.05) suggesting a more systematic approach to reading.

Conclusion: Eye-tracking data demonstrates why thin-section CT examinations of the lungs are read more efficiently when displayed in a stack as opposed to a tiled format.