The invention aims at improving the point-based elastic registration paradigm. Point-based elastic registration is typically carried out by finding corresponding point landmarks ( 2, 4 ) in both images and using the point correspondences as constraints to interpolate the global displacement field. A limitation of this approach is that it only ensures the correspondences between structures where point landmarks ( 2, 4 ) can be identified. Alternative concepts are limited by high computational costs for optimization. The concept of the invention provides a method and a system ( 1 ) wherein additional deformation field constraints are imposed by: partitioning (PART (I<SUB>S</SUB>, I<SUB>T</SUB>)) one or more restricted structures corresponding in the first ( 3 ) and the second ( 5 ) image and imposing additional constraints (f<SUP>Add</SUP><SUB>part</SUB>) derived from a-priori-knowledge to the one or more restricted structures. Preferred examples are i) pairs of interactively defined point landmarks ( 25 ), ii) landmarks resulting from automatic identification of corresponding structures in form of a line ( 23 ) or an area ( 27 ) or a form or a boundary ( 29 , <FIGREF IDREF='DRAWINGS'>FIG. 3</FIGREF>) thereof, iii) different material properties (tissue 1 , tissue 2 ) of corresponding structures, iv) physiological constraints establishing more general correspondences.
Method of Model-Based Elastic Image Registration For Comparing a First and a Second Image