颅内动脉瘤快速虚拟支架和血流动力学数值模拟研究

Objective The virtual stent algorithm was used to simulated the state of real intravascular stent deployment. Meanwhile, the virtual postoperative model was numerically simulated to evaluate the changes of hemodynamic parameters before and after virtual stent implantation. Methods One patient with basilar aneurysm (aneurysm diameter; 10.93 mm and grade 1 enhancement of aneurysm wall) in the Center of Neurointervention, Beijing Tiantan Hospital Affiliated to Capital Medical University was included in September 19,2014. The high resolution magnetic resonance imaging of enlarged aneurysm(aneurysm diameter; 12. 83 mm) was recombined for the geometric model of specific aneurysm. The geometric model was segmented and smoothed, through the rapid simulation algorithm of virtual stent based on simple deformable mesh, the Pipeline dense mesh stent deployment was quickly and effectively simulated, and the position and morphological structure of the stent after deployment were obtained. At the same time, through the solid modeling of the stent and the hemodynamic simulation calculation of the virtual postoperative aneurysm, the quantifiable hemodynamic parameters (including the time average wall shear stress, the oscillatory shear index, the number of gradient turbulence, the wall shear stress gradient, pressure, mass flow rate and velocity) were compared before and after surgery to analyze the changes in blood flow patterns of aneurysm after virtual stent placement. Results The time average wall shear stress, wall shear stress gradient, maximum gradient oscillation number and other hemodynamic parameters in aneurysm sac after operation were significantly lower than those before operation, while the pressure and maximum oscillation shear index were higher compared with those before surgery. The maximum time average wall shear stress of aneurysm sac decreased from 5. 277 Pa to 2. 701 Pa, decreasing by 48. 816%. The maximum wall shear stress gradient decreased from 16 078. 273 Pa/m to 8 995. 226 Pa/m, with a decrease of 44. 054% . The maximum value of gradient oscillation number decreased from 0. 938 to 0. 919, with a decrease of 2. 026% . The maximum pressure increased from 13 155. 029 Pa before operation to 13 247. 047 Pa after operation, increasing by 0.699%. The maximum value of oscillation shear index increased from 0.462 to 0.468, with an increase of 1.299%. The mass flow through the neck plane decreased from 0. 344 g/s to 0.000 25 g/s. The outlet mass flow of the right posterior cerebral artery increased from 0.882 g/s preoperatively to 0.945 g/s postoperatively, increasing by 7.143%. The flow rate increased from 1.243 m/s to 1. 302 m/s, with an increase of 4.747%. Conclusion The combination of virtual stent algorithm and computational fluid dynamics simulation can provide the changes of hemodynamic parameters before and after operation for the interventional planning of intracranial aneurysms.