Riemannian elasticity: a statistical regularization framework for non-linear registration

  • Authors:
  • X. Pennec;R. Stefanescu;V. Arsigny;P. Fillard;N. Ayache

  • Affiliations:
  • INRIA Sophia - Projet Epidaure, Sophia Antipolis Cedex, France;INRIA Sophia - Projet Epidaure, Sophia Antipolis Cedex, France;INRIA Sophia - Projet Epidaure, Sophia Antipolis Cedex, France;INRIA Sophia - Projet Epidaure, Sophia Antipolis Cedex, France;INRIA Sophia - Projet Epidaure, Sophia Antipolis Cedex, France

  • Venue:
  • MICCAI'05 Proceedings of the 8th international conference on Medical image computing and computer-assisted intervention - Volume Part II
  • Year:
  • 2005

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Abstract

In inter-subject registration, one often lacks a good model of the transformation variability to choose the optimal regularization. Some works attempt to model the variability in a statistical way, but the re-introduction in a registration algorithm is not easy. In this paper, we interpret the elastic energy as the distance of the Green-St Venant strain tensor to the identity, which reflects the deviation of the local deformation from a rigid transformation. By changing the Euclidean metric for a more suitable Riemannian one, we define a consistent statistical framework to quantify the amount of deformation. In particular, the mean and the covariance matrix of the strain tensor can be consistently and efficiently computed from a population of non-linear transformations. These statistics are then used as parameters in a Mahalanobis distance to measure the statistical deviation from the observed variability, giving a new regularization criterion that we called the statistical Riemannian elasticity. This new criterion is able to handle anisotropic deformations and is inverse-consistent. Preliminary results show that it can be quite easily implemented in a non-rigid registration algorithms.