Method for registration of a first image data set (1) and a second image data set (2) of a target region of a patient, wherein the first and the second image data sets (1, 2) have been acquired using different imaging modalities or using different imaging techniques on the same imaging modality, the method comprising:- selecting a first anatomical structure which is visible in the first image data set (1), and a second anatomical structure which is visible in the second image data set (2), such that there is a known geometrical relationship between at least extended segments of the anatomical structures,- by evaluating the first and second image data sets (1, 2), automatically determining a first geometry information describing the geometry of at least a part of the first anatomical structure comprising the respective segment and a second geometry information describing the geometry of at least a part of the second anatomical structure comprising the respective segment,- automatically optimizing transformation parameters describing a rigid transformation of one of the anatomical structures with respect to the other and geometrical correspondences between features in the first and second geometry information by minimizing deviations from the known geometrical relationship, and- determining registration information (3) from the optimized transformation parameters.
