1. A device ( 24 ) for 3D-originated cardiac roadmapping, comprising a processing unit ( 26 ); an interface unit ( 28 ); and a display ( 30 ); wherein the interface unit ( 28 ) is adapted to provide 3D+t image data of a vascular structure of an object; and to provide 2D image data of the object, which object comprises the vascular structure, the 2D image data comprising at least one 2D image; wherein the processing unit ( 26 ) is adapted to project the vascular structure, thereby generating a plurality of mask images on the basis of the 3D+t image data; to register the at least one 2D image with one of the plurality of the mask images; wherein the registration comprises finding the maximum of a similarity factor between the mask images and the at least one 2D image; and to generate a combination of the at least one 2D image and a projection of the vascular structure on the basis of the 3D+t image data according to the registration; wherein the display ( 30 ) is adapted to display the combination as a guiding vessel tree projection; and wherein an element ( 38 ) is located inside the vascular structure ( 202 ), which element is visible in the 2D image data ( 118 ); and wherein the registration is based upon the element.