In this work we evaluate a novel method for multi-modal image registration of MR images. The key feature of our approach is a new distance measure that allows for comparing modalities that are related by an arbitrary gray-value mapping. The novel measure is formulated as least square problem for minimizing the sum of squared dierences of two images with respect to changing gray-values of one of the images. It turns out that the novel measure can be computed explicitly and allows for very simple and ecient implementation. We compare our new approach to rigid registration with cross-correlation, mutual information, and normalized gradient fields as 

distance measure.