Mesh generation is a critical step in image-based computational fluid dynamic investigation of vascular districts. While structured hexahedral meshes are known to be superior to unstructured meshes for CFD/FEA simulations, their use has been very limited due to the complex and non-automated generation procedure. We propose a new meshing strategy to generate structured conformal hexahedral meshes inside a realistic vascular lumen by combining synthetic descriptors of vascular topology (centerlines and radii of the maximal inscribed spheres) available in vmtk with powerful geometrical tools implemented in pyFormex, both open source software packages. The final volume mesh closely matches the original surface and can be classified as optimal following usual cell-quality metrics, thus suitable for accurate CFD applications.