Spatio-temporal Visualization of Regional Myocardial Velocities

Cardiovascular disease is the leading cause of death worldwide according to the World Health Organization (WHO). Nearly half of all heart failures occur due to the decline in the performance of the left ventricle (LV). Therefore, early detection, monitoring, and accurate diagnosis of LV pathologies are of critical importance. Usually, global cardiac function parameters are used to assess the cardiac structure and function, although regional abnormalities are important biomarkers of several cardiac diseases. Regional motion of the myocardium, the muscular wall of the LV, can be captured in a non-invasive manner using the velocity-encoded magnetic resonance (MR) imaging method known as Tissue Phase Mapping (TPM). To analyze the complex motion pattern, one typically visualizes for each time step the radial, longitudinal, and circumferential velocities separately according to the American Heart Association (AHA) model, which makes the comprehension of the spatio-temporal pattern an extremely challenging cognitive task. We propose novel spatio-temporal visualization methods for LV myocardial motion analysis with less cognitive load. Our approach uses coordinated views for navigating through the data space. One view visualizes individual time steps, which can be scrolled or animated, while a second view visualizes the temporal evolution using the radial layout of a polar plot for the time dimension. Different designs for visual encoding were considered in both views and evaluated with medical experts to demonstrate and compare their effectiveness and intuitiveness for detecting and analyzing regional abnormalities.