1. A method for obtaining registration of a three-dimensional pre-operative image data set of an anatomical vessel tree with corresponding intra-operative image data reconstructed from two-dimensional images of the vessel tree obtained in an X-ray imaging system, comprising: determining the orientation direction of a vessel from a pre-operative image data set, and determining the orientation direction of the vessel from the X-ray image planes, and determining a transformation of the three-dimensional image data to obtain a best fit registration of the direction derived from the pre-operative image data set with the direction derived from the X-ray image data points.