Blood vessels are capable of continuous structural adaptation in response to changing local conditions and functional requirements. Theoretical modelling approaches have stimulated the development of new concepts in this area that allows investigation of the complex relations between adaptive responses to multiple stimuli and resulting functional vascular properties.
With aid of computational fluid dynamics, wall shear stress (WSS) can be estimated using the equation: WSS = Viscosity model * Shear rate at the wall. In order to compute WSS it is necessary to define the geometry of the vessel. For this MRI and CT data is used. Automatic as well as semi-automatic border delineation is performed using locally developed methods. With aid of computational fluid dynamics, based on Navier-Stokes equations, and appropriate boundary conditions it is possible to compute the velocity and pressure field of the whole domain in 3D. The shear rate, the spatial derivates of the velocity, is defined from the equation solutions, and compared with the measured velocity vectors collected by MRI. From this, pressure drop, as well as WSS vectors and flow field parameters may be defined and combined with modern image processing methods.
MRI of the aorta, colour shows WSS magnitude, streamlines describe the flow colour by velocity magnitude, and red arrows show WS.
Last updated: 2011-05-23