小波包分析在脑血流动力学研究中的应用

The application of wavelet packet in cerebral hemodynamics analysis

目的:在单侧脑血流量上升阶段,根据脑血流量的变化速度曲线和加速度曲线,分析脑血流动力学特征。方法:人头部单侧脑血流量变化曲线,经小波包分解后,得到各种平滑滤波后的速度曲线和加速度曲线。结果:在脑血流量上升阶段,其血流量变化速度在前半段时间内平稳增加,在后半段时间内平稳降低,呈对称状;在脑血流上升阶段,其血流量变化的加速度在前半段时间内完成由增加到下降的过程,在后半段时间内较平稳,呈不对称状。结论:对于有明确物理意义的非随机信号,经小波包分解得到的各种平滑滤波后的速度曲线和加速度曲线,更适合用于进行动力学系统的状态分析;在脑血流量上升阶段,其血流量变化速度和加速度均可以反映出脑血管的特性。

AIM:To analyze the characteristics of cerebral hemodynamics at the increasing stage of blood stream flow in single side of the brain,according to the curves of velocity and acceleration of the blood stream flow. METHODS:The curves of blood stream flow in single side of the brain were decomposed by the wavelet packet,and curves of smoothed velocity and acceleration after smooth filter were obtained. RESULTS:At the increasing stage of blood stream flow in the brain,the velocity increased smoothly at the first half stage and decreased at the second half stage,the shape of its curve was symmetric.The acceleration increased first and then decreased at the first half stage.It became relatively stable at the second half stage,the shape of its curve was asymmetric. CONCLUSION:For those non stochastic signals of certain physical explanation,the curves of smoothed velocity and acceleration after smooth filter obtained after decomposition by the wavelet packet,are more suitable for the state analysis of dynamic system.At the increasing stage of blood stream flow in the brain,the characteristics of artery in the brain can be reflected by the velocity and the acceleration.