Geometric reconstruction of the rat vascular system imaged by MRA

Angiography plays a major role in analyzing brain activity (fMRI), tumor development, and ischemia. Exact knowledge of spatial distributions of arteries and veins is necessary. Unfortunately, commonly used non invasive MR approaches are biased by incomplete representations of vascular components in a single dataset. Therefore, we developed specialized algorithms, allowing generation of firstly more complete and secondly undistorted geometric models of the vascular system by fusing information from separate scans of the same specimen. Hereby each scan stresses different aspects of the vascular system like enhancing veins by use of contrast agents. The processing consists of a snake-based vessel reconstruction and a multiscale topological alignment of vessel parts. Our results show, that using contrast agents, not only putative veins appear, but some vessels (arteries as well as veins) also vanish. The latter could be due to complete saturation of the exited (inflowing) blood with contrast agent, which would result in total signal loss.