Three-dimensional motion and deformation of the heart wall: estimation with spatial modulation of magnetization--a model-based approach.

Abstract

A method for in vivo estimation of the three-dimensional (3D) motion and deformation of the heart from tagged magnetic resonance images of the myocardium is presented. The method is based on a 3D deformable model fitted to the motion of tagged points in two views (short and long axes), which results in a comprehensive kinematic model of the dynamic geometry of the left ventricle. The method was applied to data obtained in four healthy volunteers, and data were pooled according to position within the model. Analytic modeling demonstrated that the calculated strain field was relatively invariant to the type of smoothing constraint applied; the greatest error was in the circumferential-radial shear strain. Displacement, torsion, and strain extracted from the model agreed with previous results of two-dimensional MR imaging analyses and 3D studies involving the implantation of radiopaque beads in canine myocardium. The model-driven approach provides an accurate and flexible technique for noninvasive estimation of 3D in vivo deformation of the human heart.