Analysis Method Based On Doppler Ultrasound Of The Brain Blood Flow

As an important branch of medical ultrasound, Doppler Ultrasound blood flow detection technology is a significant in lossless diagnosis for the disease of blood circulation system. Because the flowing of blood contains a lot of information about diseases and organs, Doppler ultrasound blood flow detection technology can not only be used in cardiovascular disease diagnosis, but also in other disease diagnosis as an auxiliary means. In the detection system, the analysis method of blood flow is the dominant factor. The method is mainly based on spectrogram. It is very significative to study and research the methods for analyzing blood flow.The theories and models of time and frequency analysis methods are discussed in this dissertation. Then the simulation is carried out. Firstly, a blood flow signal of carotid is synthesized based on theoretical model of Doppler blood signal and maximum Doppler frequency waveform. It is used for estimating the blood of craniocerebral . Secondly, STFT, WT, Wigner-Ville, Choi-Williams are adopted to analyze the synthesized blood signal. According to the non stability of Doppler signal, the model parameters are adjusted to get better results. Lastly, according to the TFD and computing speed, the advantage and disadvantage of four kinds of methods are discussed.The simulation results show that STFT is plays a lead role in real-time clinic application because of its high computing speed. But it has a low precision. Choi -Williams is the best in analyzing, but it is not used in real-time apparatus because of low speed, large amounts of computation. The precision and computing speed of WT and Wigner -Ville are between these methods. But the mother wavelet has a significant influence to analyze results. It makes WT has a better prospect in analyzing nonstationary signal.