1. A method of rendering a medical image, comprising: providing a 3D voxel dataset of the heart; generating a 3D vector representation of a selected part of the heart; blending the 3D voxel dataset and the 3D vector representation in a common buffer; and rendering the medical image, wherein said rendering is based on the blended 3D voxel dataset and the 3D vector representation, such that the selected part of the heart is highlighted.