In this paper we propose the usage of a very efficient contact implementation for modeling the brain-skull interaction. This contact algorithm is specially design for our Dynamic Relaxation solution method for solving soft-tissue registration problems. It makes possible the use of complex biomechanical models which include different nonlin-ear materials, large deformations and contacts for image registration. The computational examples prove the accuracy and the computational efficiency of our methods. For a model having more than 50000 degrees of freedom, a complete simulation can be done in less than a minute.