快速原型技术建立人颅段颈内动脉弯曲的动物模型及Willis覆膜支架的柔顺性测试

A new experimental model of intracranial internal carotid artery and its application in testing the navigability of the covered stents

目的在犬体内建立人颅段颈内动脉系列弯曲形态的动物模型,并测试Willis覆膜支架柔顺性。方法3T磁共振3D-TOFMRA序列采集头颅横断面DICOM格式图像,导入MATERIALISEMIMICS和Pro-E软件,做出管状三维数字模型。根据该文件利用快速原型技术制作出TangoPlus材料的实体模型并硅胶涂层。将犬两侧颈内动脉切断,一端结扎,一端穿过模型做端端吻合,得到人颅段颈内动脉弯曲形态的动物模型。1周后在DSA下置入Willis覆膜支架8枚(3.5mm×16mm2枚,3.5mm×13mm2枚,3.5mm×10mm2枚,3.5mm×7mm2枚)通过模型段血管释放到远端,设对照2枚。结果在犬体内成功复制了人颅段颈内动脉弯曲形态的动物模型10例。Pro-E软件中进行图像融合比较,模型血管与志愿者颈内动脉高度相似。Willis覆膜支架分组测试时,无血管痉挛和急性血栓形成,测试后病理检查3.5mm×16mm组可见血管内膜及中膜不同程度损伤,3.5mm×13mm组可见内皮损伤及肿胀,3.5mm×10mm组仅见内皮肿胀,3.5mm×7mm组内皮肿胀更少见。结论本实验模型具有高度可控性,可重复性和真实性,手术操作简单,可用于神经介入材料的研究和测试,为神经介入医师培训提供了可靠的工具。Willis覆膜支架具有较好的柔顺性,在弯曲血管中长度越小对血管内膜损伤越小。

Objective By using rapid prototyping technique to establish a vascular model in dogs with its twisting shape simulated to the human intracranial carotid artery （ICA） and by using this vascular model to test the navigability of the Willis covered stents. Methods A cultivated digital tube was made based on the raw MR images of human ICA. Then the digital tube was transferred into a real physical model in a 3D rapid prototyping machine. Silicon was coated. The carotid arteries of canine were exposed and cut, and then the tube was put through and anatomized to get the vascular model. Eight e-PTFE covered stents （two each at size of 3.5 mm×16 mm, 3.5 mm ×13 mm, 3.5 mm ×10 mm and 3.5 mm× 7 mm, Shanghai Mieroport Co. Ltd. ） were implanted one week later. Two clogs were taken as control group. Device performance was evaluated by angiography and histopathological examination. Results Ten animal models were successfully established. Neither vascular spasm nor thrombosis was seen on angiography. Destruction of tunica media was found in the group of 3.5 mm×16 mm and destruction of endothelium in the group of 3.5 mm×13 mm, while only flattening of the endothelium was noted in both groups of 3.5 mm×10 mm and 3.5 mm× 7 mm. Conelusion Simulating the three-dimensional anatomy of human ICA and providing an effective tool for the research and for the testing of neurovascular devices, this experimental vascular model can be easily established and the procedure is of high controllability, repeatability and faetuality. It is also a useful devise in training the neuroradiologists and interventional physicians. The navigability of the tested covered stents becomes decreased with the increasing of its length. （J Intervent Radiol, 2009, 18： 136-140）