Blood Flow Measurement Based On Ultrasound Doppler Spectrogram

Blood flow is an important parameter reflecting the circulation of blood flow of human.For example,blood flow measurement is an important method to evaluate cardiac dysfunction and cardiovascular disease.It is also an indispensable step in evaluating the maturity of arteriovenous fistula.More importantly,since the physiological manifestation of ischemic stroke is abnormal cerebral blood flow,the cerebral blood flow has become a potential predictor of stroke risk.Accurate non-invasive blood flow measurement has been an active research for researchers in recent years.In the field of ultrasound,the blood flow is traditionally obtained by multiplying the cross sectional area of blood vessel by the average blood speed in the cross section area,or by the integral of the product of each cross section area element and blood velocity of the element.However,both methods are affected greatly by the measurement precision of the area and the velocity.A new algorithm,which was based on the Doppler blood flow spectrogram,was proposed to measure the blood flow in this paper.In this algorithm,it avoided the error of the measurement of cross sectional area since there is no need to measure the area.Therefore,blood flow measurement can be conveniently performed by the method,especially for imaging positions where it is difficult to measure the cross-sectional area of the blood vessel.In this paper,we concentrated on the algorithm and the ultrasound Doppler system.The main research work is as follows:1?A new algorithm for the blood flow measurement based on the Doppler spectrogram was proposed in this paper.In the algorithm,the blood flow was calculated according to a double integral of a Doppler blood flow spectrogram.The feasibility of the blood flow measurement algorithm based on Doppler blood flow spectrogram was theoretically analyzed.2?To verify the feasibility and accuracy of the proposed algorithm,experiments were performed on the Doppler blood-mimicking phantom using the SonixTouch ultrasonic system.We calculated the blood flow value according to the algorithm and analyzed the value by least square method.We also obtained the correction coefficients by system calibration.The correction coefficients is used to correct the measurement results and calculate the error of measurement.The accuracy of traditional blood flow measurement method and the proposed algorithm was compared on the phantom.In-vivo experiments were also carried out to verify the feasibility of the algorithm.3?A new single-channel Doppler signal demodulation scheme is proposed.This scheme uses a multiplier to realize the demodulation of Doppler signals according to the principle of spectral shift of linear system signals.This scheme is used to design a simple and portable continuous wave spectrum Doppler system.This paper mainly presents the circuit module design of the system,including ultrasonic transmission circuit,preamplifier circuit,single channel demodulation circuit,second-order amplification and voltage boosting circuit,AD acquisition,USB transmission module and so on.Circuit simulation or experimental tests were carried out,and the results show the feasibility and accuracy of each module and circuit.