Field-based parameterisation of cardiac muscle structure from diffusion tensors

Abstract

This paper presents a robust method to directly construct parametric representations of myocardial structure using a left ventricular (LV) finite element model customised to diffusion tensors derived from cardiac diffusion tensor magnetic resonance images (DTMRI). This method avoids the need to solve the eigenvector problem, and therefore avoids issues due to ambiguous eigenvector directions, and the nonuniqueness of eigenvectors in regions of isotropic diffusion. Finite element parameters describing the fibre orientations of a geometric model of the LV are directly fitted to diffusion tensors using non-linear least squares optimisation. The method was tested using ex vivo DTMRI data from a Wistar-Kyoto rat and compared against the conventional eigenvector analysis. Close agreement was found in most regions, except at some boundary locations, and in regions with low fractional anisotropy.