DENSE NONRIGID MOTION ESTIMATION IN SEQUENCES OF MEDICAL IMAGES USINGDIFFERENTIAL CONSTRAINTS

We describe a new method for computing the displacement vector field i n time sequences of 2D or 3D images (4D data). The method is energy-mi nimizing on the space of correspondence functions; the energy is split into two terms, with one term matching differential singularities in the images, and the other constraining the regularity of the field. In order to reduce the computational time of the motion estimation, we u se an adaptive image mesh, the resolution of which depends on the valu e of the gradient intensity. We solve numerically the minimization pro blem with the finite element method which gives a continuous approxima tion of the solution. We present experimental results on synthetic dat a and on medical images and we show how to use these results for analy zing cardiac deformations.