Virtual angioscopy in human coronary arteries with visualization of computational hemodynamics

We are presenting a comprehensive system for fusion of intravascular ultrasound (IVUS) data and x-ray angiography, aiming to create a geometrically accurate 3-D or 4-D (3-D plus time) model of the coronary vasculature. For hemodynamic analyses, methods of computational fluid dynamics (CFD) are applied to the reconstructed data, resulting in quantitative estimates of the wall shear stress. Visualization is performed using the Virtual Reality Modeling Language (VRML). Lumen and adventitia borders are modeled as surfaces using indexed face sets; quantitative results are encoded as color per vertex. The endoscopic mode (virtual angioscopy) allows an interactive fly-through animation with variable speed along with arbitrary positioning within the vessel. Since this functionality exceeds those of the standard VRML animation nodes, an external prototype library containing VRML and JavaScript definitions has been developed that provides a 3-D graphical user interface to navigate within the endoscopic mode. The control panel is available on demand, but does neither obstruct any vessel features when not needed, nor does it limit the viewport for the scene. Preliminary results showed a good feasibility of the overall procedure, and a high reliability of the fusion and CFD methods as well as the visualization with the virtual endoscopy VRML library.