气体栓子超声多普勒信号的仿真研究

Simulation of gas emboli Doppler ultrasound signals

通过分析研究气体栓子的超声多普勒信号的特征及其成因,建立气体栓子的超声多普勒仿真模型,为后续的气体栓子与固体栓子的分类提供理论基础。先利用超声辐射力和液体黏滞阻力的模型计算气体栓子所受的超声辐射力和黏滞阻力,然后计算气体栓子在血管内的径向加速度和轴向加速度,并从加速度得到气体栓子在血管内的运动轨迹,最后建立气体栓子的计算机仿真模型。实验中仿真合成气体栓子和固体栓子的超声多普勒信号,对信号的分析结果表明,相比于固体栓子,仿真的气体栓子信号受到作用力而产生的加速度将导致气栓信号在多普勒声谱图上频域的展宽,当气体栓子由低速区域加速到高速区域再由高速区减速至低速区将会在声谱图上体现为"V"型,若只有单一的加速或减速运动将只表现为斜线型。将仿真的气栓信号与临床采集的气栓信号进行比较,发现两者的特征是吻合的,说明气栓超声多普勒信号的仿真方法是合理的。

The simulation model of the gas emboli will be established by analyzing the features and reasons of the gas emboli Doppler ultrasound signals. It is useful for the further classification of the solid emboli and gas emboli. Firstly, the model of the radiation force and the drag force is used to calculate the forces acting on the gas emboli. Secondly, the acceleration of the gas emboli is calculated in both the radial direction and the axial direction of the vessel, which is used to calculate the trajectory of the gas emboli in the vessel. Lastly, the computer simulation model is established for the gas emboli. The Doppler ultrasound signals of the gas emboli and the solid emboli are generated in the simulation experiment. It is shown from the experiment that compared with the solid emboli, the gas emboli acted by the radiation force and the drag force will result in the frequency-domain broaden in the Doppler spectrogram. When the gas emboli circulate from the low speed area to the high speed one and then from the high speed area back to the low speed one, a ＂V＂ shape will be shown in the spectrogram for the gas emboli signals. When the gas emboli circulate from the low speed area to the high speed one or from the high speed area to the low speed one, a diagonal shape will be shown for the gas emboli signals. It is also shown that the features of the simulated gas emboli signals match with those of the gas emboli signals collected from clinic. All demonstrate that the simulation method of the gas emboli is reasonable.