A 3D-originated cardiac roadmapping device and method include providing 3D+t image data of a vascular structure of an object; acquiring 2D image data of the object that includes the vascular structure, where the 2D image data includes at least one 2D image. The method further includes projecting the vascular structure, thereby generating mask images based on the 3D+t image data; and registering the at least one 2D image with one of the mask images. The registration includes finding the maximum of a similarity factor between the mask images and the at least one 2D image. The method further includes generating a combination of the at least one 2D image and a projection of the vascular structure based on the 3D+t image data according to the registration; and displaying the combination as a guiding vessel tree projection.