Estimation of epicardial strain using the motions of coronary bifurcations in biplane cineangiography

A quantitative method for estimating epicardial deformation from the motion of the superficial coronary arteries is described. A structural model of the time-varying surface is constructed using tensor product basis functions which are bicubic Hermite in the spatial domain and sinusoidal in the temporal domain. The locii of the superficial coronary arteries are reconstructed interactively at diastasis and the bifurcations are tracked semiautomatically throughout as cardiac cycle. An initial surface is fitted to the vessels at diastasis and is subsequently deformed under the influence of the bifurcations. The Lagrange-Green strain tensor is used to obtain a complete description of surface strain over the entire region spanned by the model. The calculated deformation field varies smoothly over space and time and is not constrained by assumptions of isotropy or piecewise homogeneity. Results for a single cycle of a human heart are presented.