Statistical Comparison of Cardiac Fibre Architectures

In this paper, a statistical atlas of DT-MRIs based on a population of nine ex vivo normal canine hearts is compared with a human cardiac DT-MRI and with a synthetic model of the fibre orientation. The aim of this paper is to perform a statistical inter-species comparison of the cardiac fibre architecture and to assess the quality of a synthetic description of the fibre orientation. We present the framework to build a statistical atlas of cardiac DT-MRIs providing a mean and a covariance matrix of diffusion tensors at each voxel of an average geometry. The comparison of human and synthetic data with this atlas involves the non-rigid registration into the average atlas geometry where voxel to voxel comparison can be performed. For each eigenvector of the diffusion tensors, we compute the angular difference with the average atlas and its Mahalanobis distance to the canine population. The results show a better consistence of the fibre orientation than the laminar sheet orientation between the human and the canine heart, while the homogeneous synthetic model appears to be too simple compared to the complexity of real cardiac geometry and fibre architecture.