Analysis of Cerebral Vascular System and Blood Flow Prediction System by 4D-CG Visual Simulation

近年来，需要外科手术治疗的脑血管疾病的数量不断增加。虽然这些手术大多需要在出血部位止血，但到目前为止，在需要的部位止血通常很困难。在许多情况下，脑血管系统的血液供应源或血管的一部分（Willis环等）曾经暂时关闭但是这些关闭的方法有时会导致大脑其他部位的缺血，并对患者造成致命的风险。人们认为，为了使神经外科手术的风险最小化，通过血流估计系统（医生可以通过三维图形模拟手术的系统）向医生提供预见性知识是有效的。本研究首先将脑血管系统看作是一种流体回路，将脑血管系统中的“Willis环”看作是一种流体回路。将Willis环看作由9个分叉管组成的系统。其次，制作了脑血管系统和颅骨的三维计算机图形（3D-CG），实时显示上述结果。这些3D-CG是基于从脑血管系统的X线片和从颅骨的CT片检测到的数据。这些图形可以在显示器上旋转，转移，分割成一些部分，并从各个方向观察系统的内部结构和外部图形。作为上述计算结果的每个脑血流量或血压对于每个幅度以不同的颜色显示，因为它们可以一目了然。

The number of cerebral vascular diseases which require surgical operation has recently been increasing. Although the most of these operations need the hemostasis at hemorrhagic regions, it is generally difficult to stop bleeding at a required part, so far. In many cases, a blood supply source to the cerebral vascular system or a part of the vascular (Willis ring, etc.) used to be temporally shut off. But these methods of shutting off sometimes cause ischemia at other parts of brain and fatal risks to patients.It is thought that to minimize the risk on neurosurgical operations it is effective to give medical doctors foresight knowledges with the blood flow estimation system : the system with which doctors could simulate the operations through three dimensional graphics. In this study, the system has been developed.In this study, first, a cerebral vascular system which is organized by 'Willis ring' has been regarded as a kind of fluid circuit. And 'Willis ring' is considered as a system which consists of nine forked pipes.Second, the three dimensional computer graphics (3D-CG) of the cerebral vascular system and the skull bone were made to display the above results in real-time. These 3D-CG are based on the data which are detected from the X-ray films of the cerebral vascular system and from CT films of the skull bone. These graphics are possible on the display to rotate, to transfer, to be divided into some parts, and to observe the inner structure and outer figure of the system from every direction. Each cerebral blood flow rate or blood pressure as the results of above calculation was displayed in a different color for each magnitude, as they could be understood at a glance.