Computer simulation of blood flow using short te magnetic resonance angiography

Using computer simulation of pulsatile blood flow and magnetic resonance angiography (MRA), we investigated the hemodynamic factors leading to the formation and evolution of 1) atherosclerotic plaque in carotid arteries, and 2) aneurysms in the abdominal aorta. Phantom and patients were imaged by MRA, color Doppler and/or digital subtraction angiography (DSA). Computer modelling was carried out by finite element analysis to solve the Navier-Stokes equation. In the analyzed vessels, voxels representing pathology were digitally removed. Local wall shear stress and pressure were also calculated as a function of a cardiac cycle. There was general agreement between MRA, color Doppler, DSA and computer simulation in both phantom and in-vivo experiments. In MRA, the best results were achieved by short TE, thin slice 2D “time-of-flight” technique, which was least susceptible to the changes in velocity profiles, and best correlated with Doppler and computer simulation. The hemodynamic information obtained from analyzed carotid arteries predicted that during late systole, flow separation exists at the exact locations from where the plaque voxels were removed. We were also able to predict the location of abdominal aortic aneurysm and its evolution toward the distal vessel intima. In conclusion, MRA accurately depicted flow disturbances, and computer simulation of blood flow proved to be a good predictor of the development of vascular pathology.