Gaze patterns reflect and predict expertise in dynamic echocardiographic imaging

Echocardiography is the most important modality in cardiac imaging. Rapid valid visual assessment is a critical skill for image interpretation. However, it is unclear how skilled viewers assess echocardiographic images. Therefore, guidance and implicit advice are needed for learners to achieve valid image interpretation.

Using a signal detection approach, we compared 15 certified experts with 15 medical students in their diagnostic decision-making and viewing behavior. To quantify attention allocation, we recorded eye movements while viewing dynamic echocardiographic imaging loops of patients with reduced ejection fraction and healthy controls. Participants evaluated left ventricular ejection fraction and image quality (as diagnostic and visual control tasks, respectively).

Experts were much better at discriminating between patients and healthy controls ( $$ of 2.58, versus 0.98 for novices). Eye tracking revealed that experts fixated diagnostically relevant areas earlier and more often, whereas novices were distracted by visually salient task-irrelevant stimuli. We show that expertise status can be almost perfectly classified either based on judgments or purely on eye movements and that an expertise score derived from viewing behavior predicts diagnostic quality.

Judgments and eye tracking revealed significant differences between echocardiography experts and novices that can be used to derive numerical expertise scores. Experts have implicitly learned to ignore the salient motion cue presented by the mitral valve and to focus on the diagnostically more relevant left ventricle. These findings have implications for echocardiography training, objective characterization of echocardiographic expertise, and the design of user-friendly interfaces for echocardiography.