体外循环血栓非侵入在线电阻抗成像方法

目的 在体外循环系统中，血栓的在线检测和可视化具有重要意义。本文提出了基于电阻抗成像（EIT）的体外循环血栓非侵入在线检测方法。方法 首先通过联合仿真研究了传感器尺寸对成像效果的影响。其次，根据仿真结果设计了直径为20 mm的16铜质电极EIT传感器，搭建了循环流动实验平台，并设计了静态和循环流动实验。使用尺寸为3～6 mm的猪血块代替血栓，将血块置于新鲜猪血样本中，采用Tikhonov正则化算法进行成像。将3 mm和5 mm的血块分别置于循环系统中，重建血块在传感器截面的大小和位置图像，并与高速相机拍摄结果进行对比。结果 仿真结果显示当目标物与传感器面积比（AR）不小于0.01时，传感器直径为20 mm和30 mm对应的图像相关系数（IC）均大于0.06，成像效果较好。静态成像结果显示，相对尺寸覆盖率误差（RCR）小于等于0.1。循环流动实验显示，血块经过传感器时，检测到归一化后的相对电导率变化值分别为80和200，结果显示该方法能够检测到循环系统中的血块。结论 该方法具有实时性和非侵入的优点，有望应用于体外血栓的检测。

Noninvasive and Online Detection of Thrombus in Extracorporeal Circulation Based on Electrical Impedance Tomography

Objective The online detection of thrombus and visualization are of great importance in the extracorporeal circulatory system. In this paper, a noninvasive and online detection method of thrombus in extracorporeal circulation based on electrical impedance tomography (EIT) is proposed.Methods Firstly, this paper investigates the effect of sensor size on the imaging performance through joint simulation. Secondly, a 16-copper electrode EIT sensor with a diameter of 20 mm is designed based on the simulation results, a cyclic flow experimental platform is built, and static and cyclic flow experiments are designed. Instead of thrombus, pig blood clots of 3-6 mm in size are placed in fresh pig blood samples and image using the Tikhonov regularization algorithm. The 3 mm and 5 mm clots are placed in the circulation system, and the images of the size and position of the clots in the sensor section are reconstructed by the EIT system and compared with the results taken by the high-speed camera.Results The simulation results show that the image correlation coefficients (IC) are greater than 0.06 for the sensor diameters of 20 mm and 30 mm when the target-to-sensor area ratio (AR) is not less than 0.01, and the imaging effect is well. The static imaging results show that the relative size coverage ratio is less than or equal to 0.1. The circulating flow experiments show that the normalized relative conductivity value changes of 80 and 200 are detected as the clots pass through the sensor, and the results show that the method is capable of detecting clots in the circulatory system.Conclusion The method has the advantages of real-time and noninvasive, and is expected to be applied to the detection of thrombus in vitro.