Rotation registration of medical images based on image symmetry

Abstract

Mutual Information has been used as a similarity metric in medical images registration. But local extrema impede the registration optimization process and rule out the registration accuracy, especially for rotation registration. In this paper, a novel approach to rotate registration based on image symmetry measure is presented. Image symmetry measure is defined to measure the symmetry about the possible axis. The symmetry measure is at its maximum when the possible symmetry axis is the real symmetry axis. The angle between the symmetry axes of two images can be used to estimate rotate registration parameter in advance without translation parameter. This method is of great benefit to rotation registration accuracy and avoids the disadvantage of traditional MI method searching in the multi-dimensional parameter space. Experiments show that our method is feasible and effective to rotation registration of medical images, which have obvious symmetry characteristics. © Springer-Verlag Berlin Heidelberg 2005.