Microscopic visualization of blood multihpase flow using fluorescent tracers

流场显示不仅可以定量地分析流体的速度，而且可以了解流体的流型。在每一个问题中，都有必要开发相应的技术来可视化流动。本课题的目的是发展一种新的血流可视化技术，并以此来分析各种器官中的多相流现象，我们采用荧光示踪剂进行血流可视化，并研制了一种配有硅增强型摄像机的荧光视频显微镜。在该实验系统中，悬浮在血液中的荧光粒子的运动可以在视频监控器上清晰地独立观察。利用视频监视器上两个窗口处的光强度测量值，可以评价单支血管中的颗粒流速。还可以测量血管横截面上红细胞的分布。基于荧光示踪法，我们研究了血细胞悬浮液在玻璃管或脑血管分叉处的稳态流动。通过反复录像，我们仔细检查了流动模式和速度分布。此外，我们还对大鼠大脑动脉分叉和猫大脑皮层微血管网的血流进行了活体流动观察。我们展示了多相流现象，如无细胞血浆流和红细胞聚集流。

Flow visualation is avaliable for quantative analysis of the flow velocityas well as understanding of flow pattern. It is necessary in each prob I em to dev i se the correspond ing technique tovisualize flow. The purpose of this pro-ject is to develop a new technique for visualizing blood flow, and then to analyze multiphase flow phenomena in various organs.We used fluorescent tracers for flow visualization, and developed a fluorescence video-microscope equipped with a silicon intensified video(SIT)camera. In this experimental system, motions of fluorescent particles suspended in blood could be observed clearly and independently on the video-mionitor. Using the light intensity of particles measured at two windows on t he video-monitor, we could evaluated their flow velocities in single vessels. It was also possible to measure the distribution of red cell over a cross-section of the vessel. The present method has an advantage that a large range of velocity can be measured due to the high-quality image of fluorescent tracers.Based on the fluorescent tracer method, we investigated steady flows of blood cell suspensions in glass tubes or cerebrovascular bifurcation. By repeated video-recordings, we made close examination of the flow pattern and velocity profile. Moreover, we made in vivo flow vis ualiation of blood flow in cerebral arterial bifurcations of rats and in microvascular networks of cats's cerebral cortex. We demonstrated multiphase flow phenomena such as cell-free plasma flow and red cell aggregation flow.