Reading, Fast and Slow: Characterizing Radiologists' Visual Search Through Abdominal CT for Detecting Hepatic...

Previous studies suggest that "drilling" (eyes fixated at one location within a slice while scrolling rapidly between computed tomography (CT) slices) may be more effective than "scanning" (eyes move rapidly to search within each slice while scrolling slowly between slices) for detecting lesions, but evidence has been limited. The purpose of this study is to examine the association between sensitivity and either drilling or scanning for liver metastasis detection.

Twenty-five radiologists blinded to clinical and previous imaging information marked all suspected hepatic metastases in 40 contrast-enhanced liver CT exams while being monitored by eye-tracking technology. Eye movements were registered to the corresponding liver segment and slice. All livers and proven metastases were demarcated into Couinaud segments. Outcome measures included metastasis detection (sensitivity), interpretation time, average rate of scrolling, and average rate of segment change.

There were 91 metastases, and mean sensitivity was 83%. In univariate analysis, higher reader sensitivity was associated with longer interpretation time (adjusted R² = 0.35, regression coefficient = 5.25, p = 0.002) and smaller segment change rate (i.e., drilling) (adjusted R² = 0.23, regression coefficient = -4.54, p = 0.009). Scrolling rate was not associated with sensitivity (p=0.37). A regression model predicting sensitivity from both interpretation time and segment change rate yielded an adjusted R² of 0.43.

Drilling may outperform scanning in sensitivity for detection of liver metastases when measured as segment change rate, but not as scrolling rate. Longer interpretation time is independently associated with higher sensitivity.