应用CT断层图像构建颅内动脉瘤三维有限元模型的方法

Reconstruction of a finite element model of intracranial aneurysms based on CT images

目的基于螺旋CT断层原始图像，利用Mimics三维重建软件与Anasys有限元分析软件，建立颅内动脉瘤的三维有限元模型，以进一步进行颅内动脉瘤血流动力学的研究。方法利用GE Lightspeed16排螺旋CT，层厚0．625mm，层间距0．5mm，获得颅内动脉瘤的CTA图像。应用Mimics直接读入Dicom格式的原始图像，采用阈值分割与手动分割相结合的处理方法，得到最感兴趣的部位，主要包括载瘤动脉和动脉瘤，对图像进行三维计算，调用FEA模块的Remesh功能．获取颅内动脉瘤的三维模型的面网格格式．文件以lis格式保存并输出，直接导入ANSYS软件转化成IGES文件．导入ANSYS Workbench生成体网格进行血流动力学的研究。结果建立了精确、快速的颅内动脉瘤三维有限元几何模型，面网格文件可直接导入ANSYS软件进行血流动力学的研究。结论薄层螺旋CT扫描技术、Dicom医学数字图像通讯标准的应用使有限元模型的建立更为精确，Mimics软件可以直接建立颅内动脉瘤的三维有限元几何模型，提高了效率。

Objective To establish a three-dimensional （3D） finite clement model ofintracranial aneurysms based on CT images for three-dimensional simulation of the hemodynamics in the aneurysms. Methods CT angiographic （CTA） images of the intracranial aneurysms were obtained using a GE Lightspeed 16-slice spiral CT with the slice thickness of 0.625 mm at the interval of 0.5 mm. The original Dicom format images were directly imported using the Mimics software. Threshold-based combined with manual segmentation of the images was carried out to acquire the region of interest including the aneurysm and parent artery, followed by 3D calculations of the images. The 3D model was remeshed and exported as an area mesh file to Ansys. The area-based file was then converted into an IGES file in Ansys, and exported to the Ansys workbench software to generate the volumetric mesh for further homodynamic study. Results A 3D finite element model of intracranial aneurysm was established, and the area mesh file could be directly introduced into Ansys software to allow homodynamic study of the aneurysm. Conclusion The application of thin-layer CT scanning and the Dicom standard allows more accurate reconstruction of the 3D finite element model of intracranial aneurysms. The Mimics software can greatly improve the efficiency of intracranial aneurysm model reconstruction.