Eye tracking as a tool to quantify the effects of CAD display on radiologists' interpretation of chest radiographs

Computer-aided detection (CAD) systems for chest radiographs are widely used; however, concurrent reader displays such as bounding-box (BB) highlights may influence interpretation. This pilot study used eye tracking to examine which aspects of visual search were affected by these factors.

We sampled 180 chest radiographs from the VinDR-CXR dataset: 120 with solitary pulmonary nodules or masses and 60 without. BBs were configured for 80 % display sensitivity and specificity. Three radiologists (with 11, 5, and 1 years of experience) interpreted each case twice-once with BBs visible and once without-after a ≥ 2-week washout. Eye movements were recorded using an EyeTech VT3 Mini. Metrics included interpretation time, time to first fixation, lesion dwell time, total gaze-path length, and lung-field coverage. Outcomes were modeled using a linear mixed model with the reading condition set as a fixed effect and case and reader as random intercepts. Primary analysis was restricted to true positives (n = 96).

Concurrent BB display prolonged interpretation time by 4.9 s (p < 0.001) and increased lesion dwell time by 1.3 s (p < 0.001). Total gaze-path length increased by 2076 pixels (p < 0.001), and lung-field coverage increased by 10.5 % (p < 0.001). The time to first fixation was reduced by 1.3 s (p < 0.001).

Eye tracking revealed measurable changes in search behavior associated with concurrent BB display during chest radiograph interpretation. These findings support this approach and highlight the need for larger studies across modalities and clinical contexts.