| Cardiovascular disease is the number one cause of the worldwide death. It is estimated in2008that, about1,730people are died of cardiovascular disease, which accounted for30percent of total global death rate. In China, the overall mortality of cardiovascular disease ranked the first and is higher than the rate in United States and Europe. This seriously endangers the life and brings the heavy burden to both families and society.Both the Digital Subtraction Angiography (DSA) and Computed Tomography Angiography (CTA) imaging technique are playing a significant role in the early screening of cardiovascular disease, clinical diagnosis, pre-surgery prediction and post-surgery evaluation. However, the DSA and CTA can just offer a way of estimation the structural information of the vessel such as stenosis, inflation and block, but lack of producing the quantitative functional information, for instance, blood flow velocity, wall pressure and shear stress.Based on the DSA and CTA image data, this paper introduce a hemodynamic simulation method, and validated its feasibility and validity by real clinical data. First, based on the two dimension DSA data, the preprocessing methods, segmentation of interesting region and system coordinated are used. Then three kinds of velocity estimation methods are tested based on these data. And significantly discuss the optical flow method of its parameters and iteration methodology. Second, the steps as segmentation of3D models using Mimics, meshed by infinite analysis software and solution of the control equation are implemented on ANSYS Workbench with CTA data. Then the several results such velocity, pressure and shear stress are gained and compared under the stead, transient and simulated PCI analysis strategy. Third, the Fractional Flow Reserve based on CT (FFRCT) method are used and compared with clinical result produced by pressure sensors based on the previous CTA computed data.It is shown in the result that, for DSA:the methods are convergent and little differences are found between their relative velocity. The developed optical flow method is with higher accuracy, fast and excellent robust quality of noise compared with the other methods; for CTA:(1) the computed result is convergent and regardless with the element size of mesh unit.(2) Stead and Transient:the distribution of steady result only due to the input condition. However the result of transient analysis is different according to the last and next input status.(3) Velocity:the velocity are increased at the stenosis but decreased at non-stenosis part after the simulated PCI; there exists a high speed flow field near the interior wall of stenosis part, and shift over after simulated PCI.(4) Wall pressure:the wall pressure increased suddenly when meets the stenosis but decrease after stenosis and the distal vessel as well. After simulated PCI, the distribution of wall pressure is much smoother than before, and the pressure decrease gradually from inlet to distal outlet.(5) Wall shear stress:the value at the stenosis is very high, 63.69Pa, and distributed sparsely; after repairing the stenosis, the wall shear stress become very low at the same part,2.59Pa, and distributed smoothly.(6) Mass flow:the ratio of pre PCI and post PCI at the stenosis of LAD is0.633.(7) FFR:comparison at different position of the vessel are little different with invasive value:RAC:FFRCT=0.87, FFR>0.8; LAD: FFRCT=0.69, FFR-0.71; LCX:FFRcr=0.83, FFR>0.8; post PCI for LAD and LCX: FFRCT=0.97and0.96.In summary, it is feasible and valuable that the hemodynamic simulation based on DSA and CTA data, which can provide lots of information in terms of functional information of vessel, included velocity, mass flow, pressure and wall shear stress, etc. Also the simulated PCI method can predict the therapy result. What’s more, as a non-invasive functional estimation of vessel, FFRCT, combined with the structural parameters offered by vessel model can improve the evaluation, research of therapy and methodology of coronary disease. |
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