5-D model for accurate representation and visualization of dynamic cardiac structures

Accurate cardiac modeling is challenging due to the intricate structure and complex contraction patterns of myocardial tissues. Fast imaging techniques can provide four-dimensional structural information acquired as a sequence of 3-D images throughout the cardiac cycle. To model the beating heart, we created a physics-based surface model that deforms between successive time points in the cardiac cycle. 3-D Images of canine hearts were acquired during one complete cardiac cycle using the Dynamic Spatial Reconstructor (DSR) and the Electron Beam CT (EBCT). The left ventricle of the first time point is reconstructed as a triangular mesh. A mass-spring physics-based deformable model, which can expand and shrink with local contraction and stretching forces distributed in an anatomically accurate simulation of cardiac motion, is applied to the initial mesh and allows the initial mesh to deform to fit the left ventricle in successive time increments of the sequence. The resulting 4-D model can be interactively transformed and displayed with associated regional electrical activity mapped onto anatomic surfaces, producing a 5-D model, which faithfully exhibits regional cardiac contraction and relaxation patterns over the entire heart. The model faithfully represents structural changes throughout the cardiac cycle. Such models provide the framework for minimizing the number of time points required to usefully depict regional motion of myocardium and allow quantitative assessment of regional myocardial motion. The electrical activation mapping provides spatial and temporal correlation within the cardiac cycle. In procedures such as intra-cardiac catheter ablation, visualization of the dynamic model can be used to accurately localize the foci of myocardial arrhythmias and guide positioning of catheters for optimal ablation.