Visual search of mammographic images: influence of lesion subtlety

The goal of this study is to determine whether mammographic lesion subtlety influences the detection accuracy and visual search parameters of radiologists.

Six radiologists searched a set of 20 mammograms with at least two lesions per image (masses and/or microcalcifications). Eye position was recorded. False-negative (FN) and true-positive (TP) decisions were correlated with lesion subtlety and visual search parameters of time to first hit, total dwell time, and number of return fixations.

Lesions with lower subtlety ratings were detected later in the search than more obvious ones (FN later than TP decisions). When subtler lesions were detected (TP), dwell time was longer than for more obvious lesions, but FN decisions received shorter total dwell. Subtler lesions, when detected (TP), received more total fixation clusters than more obvious ones, but FN decisions received fewer.

Subtle mammographic lesions are associated with significantly different visual search parameters than obvious lesions, explaining in part why they are missed more often. Developing tools to improve lesion visibility may improve detection.