Two-dimensional pulsatile hemodynamic analysis in the magnetic resonance angiography interpretation of a stenosed carotid arterial bifurcation.

A two-dimensional pulsatile hemodynamic analysis based on the finite-element technique was performed on a minimally stenosed carotid artery to identify the possible explanation for the differences in the x-ray and magnetic resonance carotid angiograms of a patient. The magnetic resonance angiogram was obtained by applying the maximum intensity projection algorithm to axial slices, acquired using the time-of-flight principle. The differences in the x-ray and magnetic resonance depictions were interpreted based on velocity profile, wall shear stress, and streamline data provided by the hemodynamic analysis. The specific contribution of the stenosis was further isolated from that of the bifurcation by comparing the flow patterns within the stenotic artery with those of its normal counterpart. The Doppler spectral velocity wave form of the patient constituted the basis for the pulsatile flow velocity specification. The analysis took into consideration the non-Newtonian viscosity of blood. The numerical procedure was validated through different convergence criteria and through shear stress comparisons. The importance of hemodynamic analyses in relation to magnetic resonance angiography was further discussed along with possible shortcomings of the technique.