CN106963424A - System and method for detecting arterial vessel viscoelasticity - Google Patents

Abstract

The invention relates to a method for detecting arterial viscoelasticity, comprising: controlling an external vibrator to vibrate on the skin close to the blood vessel; an ultrasonic probe sends a detection pulse to the skin, and records the pulse echo signal of the blood vessel tissue in the skin under each channel, And calculate the displacement of the blood vessel tissue in the skin of each channel, and filter out the pulse wave velocity in the displacement, and at the same time, the ECG acquisition machine collects the ECG signal; obtain the instantaneous propagation velocity of the strain wave, and estimate the instantaneous viscoelastic coefficient of the blood vessel ; Under the cardiac cycle, estimate the instantaneous viscoelastic coefficient of the blood vessel multiple times, and register the estimated viscoelastic coefficient with the collected ECG signal in time, and obtain the elastic modulus and viscous modulus of the blood vessel at different moments in the cardiac cycle . The invention also relates to a system for detecting the viscoelasticity of arterial blood vessels. The present invention adopts an external vibrator instead of an ultrasonic probe, which is safer and can be formed as an independent device or as an additional functional module.

Description

System and method for detecting arterial vessel viscoelasticity

technical field

The invention relates to a system and method for detecting arterial blood vessel viscoelasticity, in particular to a system and method for in vivo quantitative detection of arterial blood vessel viscoelasticity.

Background technique

Cardiovascular and cerebrovascular diseases are collectively referred to as cardiovascular and cerebrovascular diseases. disease. As we all know, cardiovascular disease is the number one killer of human beings. The number of people who die of cardiovascular and cerebrovascular diseases is as high as 15 million in the world every year. The number of cardiovascular and cerebrovascular diseases in my country is as high as 290 million, and the total annual hospitalization expenses exceed 70 billion yuan. Cardiovascular diseases The burden is increasing day by day, and it has become a major public health problem in our country.

The mechanical properties of arteries play a central role in cardiovascular function. There is a direct relationship between arterial stiffness and various cardiovascular diseases, and it is an important predictor of cardiovascular and cerebrovascular morbidity and mortality. Although the change of arterial viscoelasticity is generally systemic and affects the entire vascular system, the hardness of arteries at different locations responds differently to factors such as age, high blood pressure, and pregnancy, and arteries tend to harden , and the aortic vessel becomes soft, so accurate measurement of local arteries is very important. Since the viscoelasticity of the arterial vessel wall changes nonlinearly with blood pressure, this nonlinear change is crucial for the healthy functioning of the entire cardiovascular system and can also detect unstable plates in atherosclerosis.

In order to obtain local, instantaneous, and quantitative hardness measurements, the compression waves generated by the heart pumping blood to the blood vessels cannot be relied on, because the heart generates about one wave per second, and the shear wave elastography based on the ultrasonic radiation force can satisfy one cardiac cycle. However, this method has certain limitations: first, the safety of acoustic radiation force for blood vessel detection needs to be verified; Cut-wave imaging equipment can only be realized, the system is complicated, the cost is expensive, and it is not easy to popularize.

Contents of the invention

In view of this, it is necessary to provide a system and method for in vivo quantitative detection of arterial blood vessel viscoelasticity with higher safety.

A system for detecting arterial viscoelasticity, the system includes a main control unit, a transmitting/receiving module electromechanically connected with the main control unit and an electrocardiogram acquisition module, and an external vibrator electrically connected with the transmitting/receiving module respectively and an ultrasound probe, an ECG acquisition machine electrically connected to the ECG acquisition module, the main control unit includes a processing module, an estimation module and a registration module, wherein: the transmitting/receiving module is used for Control the external vibrator to vibrate on the skin close to the blood vessel; the transmitting/receiving module is also used to drive the ultrasonic probe to transmit detection pulses to the skin during the cardiac cycle, and record the pulse echo of the blood vessel tissue in the skin under each channel of the ultrasonic probe. wave signal; the processing module is used to calculate the displacement of the vascular tissue in the skin of each channel according to the pulse-echo signal of the vascular tissue in the skin recorded in each channel above, and filter out the pulse in the displacement Wave velocity; the ECG acquisition module is used to trigger the ECG acquisition machine to collect ECG signals under the cardiac cycle; the estimation module is used to filter out the pulse wave velocity obtained above according to the vascular tissue in the skin of each channel Displacement, the instantaneous propagation velocity of the strain wave is obtained, and the instantaneous viscoelastic coefficient of the blood vessel is estimated; the registration module is used to register the estimated instantaneous viscoelastic coefficient of the blood vessel with the collected ECG signal in time to obtain the cardiac cycle The elastic modulus and viscous modulus of blood vessels at different times.

Wherein, the ultrasonic probe is a multi-channel ultrasonic probe.

The processing module is used to calculate the displacement of the vascular tissue in the skin of each channel, specifically: the radio frequency signal received from the detection vibration element is amplified by the ultrasonic front-end circuit and processed by analog-to-digital conversion, and then processed by an orthogonal solution. Modulation processing to obtain the complex envelope of the radio frequency signal; for a certain detection point, carry out cross-correlation processing on the complex envelope signal of the adjacent frame of the echo signal, and extract the signal of tissue vibration in different depths of the point; calculate the detection point The phase of the vibration signal at a certain depth, the phase of each frame is subtracted from the phase of the adjacent frame to obtain the phase difference of each frame, and then the displacement curve of the vascular tissue over time. For two detections with a distance of Z point, the phase velocity c _L can be obtained from the displacement curves at a certain depth of the two detection points.

The estimation module is based on the Lamb wave mathematical model f(c,ω,μ ₁ ,μ ₂ )=0, specifically including:

i. Assume a set of initial values of <μ ₁ , μ ₂ >;

ii. Estimation of the phase velocity spectrum based on the "least squares criterion" which is:

iii. Calculate the estimated phase velocity spectrum The sum of squared errors between the measured phase velocity spectrum c _phase (ω) is expressed as:

iv. If α(μ ₁ ,μ ₂ ) does not reach the preset accuracy, update value, return to step ii;

Otherwise the computation stops and the resulting is the estimated value of the instantaneous viscoelastic coefficient of the blood vessel.

The registration module is specifically used for: registering the estimated instantaneous viscoelastic coefficient of the blood vessel with the collected electrocardiogram signal in time, so as to obtain the elastic modulus and viscous modulus of the blood vessel at different moments in the cardiac cycle.

The present invention also provides a method for detecting arterial viscoelasticity, the method comprising the following steps: a. controlling an external vibrator to vibrate on the skin close to the blood vessel; b. a multi-channel ultrasonic probe sending detection pulses to the skin, recording each The pulse echo signal of the blood vessel tissue in the skin under the channel, and calculate the displacement of the blood vessel tissue in the skin of each channel, and filter out the pulse wave velocity in the displacement, and the ECG acquisition machine starts to collect the ECG signal at the same time; c According to the displacement of the blood vessel tissue in the skin of each channel after filtering the pulse wave velocity obtained above, obtain the instantaneous propagation velocity of the strain wave, and estimate the instantaneous viscoelastic coefficient of the blood vessel; d. the instantaneous viscoelastic coefficient of the estimated blood vessel It is time-registered with the collected ECG signal to obtain the elastic modulus and viscous modulus of the blood vessel at different times in the cardiac cycle.

Wherein, the step b includes: the radio frequency signal received from the detection vibration element undergoes amplification and analog-to-digital conversion processing of the ultrasonic front-end circuit, and then undergoes orthogonal demodulation processing to obtain the complex envelope of the radio frequency signal; At the detection point, cross-correlation processing is performed on the complex envelope signals of the adjacent frames of the echo signal, and the signals of tissue vibration at different depths at the point are extracted; the phase of the vibration signal at a certain depth at the detection point is calculated, and each frame The phase of the adjacent frame is subtracted from the phase of the adjacent frame to obtain the phase difference of each frame, and then the displacement curve of the vascular tissue over time is obtained. For two detection points separated by Z, the displacement of a certain depth of the two detection points can be obtained. Find the phase velocity c _L from the curve.

The method also includes: repeatedly performing step a to step c within one cardiac cycle.

The specific process of the step c is as follows:

i. Assume a set of initial values of <μ ₁ , μ ₂ >;

ii. Estimation of the phase velocity spectrum based on the "least squares criterion" which is:

iii. Calculate the estimated phase velocity spectrum The sum of squared errors between the measured phase velocity spectrum c _phase (ω) is expressed as:

iv. If α(μ ₁ ,μ ₂ ) does not reach the preset accuracy, update value, return to step ii;

Otherwise the computation stops and the resulting is the estimated value of the instantaneous viscoelastic coefficient of the blood vessel.

The step d specifically includes: temporally registering the estimated instantaneous viscoelastic coefficient of the blood vessel with the collected ECG signal, so as to obtain the elastic modulus and viscous modulus of the blood vessel at different moments in a cardiac cycle.

The system and method for detecting arterial viscoelasticity in the present invention utilizes an external vibrator combined with ultrasound to quantitatively detect arterial viscoelasticity in vivo. The advantages are as follows: (1) The present invention uses an external vibrator instead of an ultrasonic probe, and has the advantages of in vivo quantitative measurement. Higher safety; (2) The present invention can be formed as an independent device, which is simple and portable, and can also be used as an additional functional module loaded on the existing color ultrasound system, which saves cost and is easy to popularize.

Description of drawings

Fig. 1 is the hardware architecture diagram of the system for detecting arterial vessel viscoelasticity in the present invention;

Fig. 2 is a flowchart of the method for detecting arterial viscoelasticity in the present invention.

detailed description

At first the physical basis of the present invention is introduced as follows:

The present invention uses an external vibrator (20HZ-1000HZ) as the excitation method of the vibration source, that is, the low-frequency vibrator is placed on the body surface, or the vibrator and the ultrasonic probe are integrated together for easy operation. The low-frequency vibration is transmitted to the body through the vibration source, and the velocity information of the shear wave caused by the vibration is detected when it propagates in the vascular tissue with an ultrasonic probe. The force is applied to the body surface of the human body to stimulate the subcutaneous vascular tissue, directly simulating the process of the doctor pressing the human body tissue with a certain frequency to perform the inspection, which is more intuitive, simple and safer, because the blood vessel is a thin When the shear wave propagates in the tissue of the layered tubular structure, the upper and lower boundaries of the cornea continue to act, resulting in refraction, reflection, and mode conversion between transverse waves and longitudinal waves to form Lamb waves.

For a viscoelastic thin plate immersed in a liquid, assuming that the density of the thin plate and the liquid are similar and the wavenumber of the compressible wave in them is much smaller than that of the Lamb wave, the asymmetric Lamb wave dispersion equation in the thin plate is as follows:

Among them, k _L =ω/c _L , ω is the angular frequency, c _L is the frequency-dependent Lamb wave phase velocity, is the wave number of the shear wave, μ is the shear modulus, ρ _m is the density of the sample (close to the density of water), h is equal to half the thickness of the sample.

The mechanical behavior of the viscoelastic thin plate is described by introducing the Voigt model, and the shear modulus μ is expressed as μ=μ ₁ +iωμ ₂ , where μ ₁ and μ ₂ are elastic modulus and viscous modulus respectively. Therefore, equation (1) can be transformed into a mathematical model about Lamb wave phase velocity c _L , frequency ω, elastic modulus μ ₁ and viscous modulus μ ₂ , as shown below.

This equation shows that Lamb wave velocity is a function of elasticity, viscosity, and Lamb wave frequency. By measuring the Lamb wave and decomposing it in the frequency domain to obtain the Lamb wave velocity c _L (ω) at each frequency, the elastic modulus μ ₁ and the viscous modulus μ ₂ of the sample can be estimated by nonlinear fitting, which is Is the physical basis of the present invention. In the specific implementation, the estimation of corneal viscoelasticity uses Equation (2) as a mathematical model, or certain approximation and simplification of Equation (2), to obtain an empirical formula for vascular viscoelasticity estimation (subject to experimental verification), as an estimate mathematical model.

Theoretical analysis and experimental research show that the speed of the Lamb wave in the blood vessel is generally 3-10m/s. In medical ultrasound, such a propagation speed can be detected with existing hardware.

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to FIG. 1 , it is a hardware architecture diagram of the system for detecting arterial viscoelasticity in the present invention.

The system includes a main control computer 101 , a transmitting/receiving module 102 , an ECG acquisition module 103 , an external vibrator 104 , an ultrasonic probe 105 and an ECG acquisition machine 106 . Wherein: the transmitting/receiving module 102 is electrically connected with the main control unit 101 , the external vibrator 104 , and the ultrasonic probe 105 respectively;

The main control machine 101 controls the operation of the entire system, and is responsible for signal control and data processing of the entire system. The main control machine 101 includes a processing module 107 , an estimation module 108 and a registration module 109 .

The transmitting/receiving module 102 includes a transmitting circuit and a receiving circuit, and the transmitting circuit includes a signal generator and a power amplifier. The ECG collection module 103 is used to trigger the ECG collection machine 106 . The external vibrator 104 is used to generate vibration on the skin surface. The ultrasonic probe 105 includes a plurality of channels, that is, a plurality of detection vibration elements, also called detection points. In this embodiment, the ultrasonic probe 105 includes 2 channels, namely, channel A and channel B, between which there is tiny spacing.

The transmitting/receiving module 102 is used to control the external vibrator 104 to generate vibration of a certain frequency on the skin close to the blood vessel. in particular:

In this embodiment, the external vibrator 104 is first placed on the skin close to the blood vessel, and the transmission control of the transmitting/receiving module 102 is triggered by the main control unit 101, and the transmitting circuit is controlled so that the external vibrator 104 generates a frequency of vibration every 0.1 seconds. This causes the blood vessel to vibrate slightly, and the vibration propagates in the blood vessel in the form of Lamb waves.

The transmitting/receiving module 102 is also used to drive the ultrasonic probe 105 to transmit detection pulses to the skin, and record the pulse-echo signals of the blood vessels in the skin under each channel.

The processing module 107 is used to calculate the displacement of the blood vessel tissue in the skin of each channel according to the pulse echo signal of the blood vessel tissue in the skin under each channel recorded by the transmitting/receiving module 102, and filter out the Pulse wave velocity in displacement. in particular:

The received echo signal r(t,k) of the detection pulse is expressed as a two-dimensional signal. Once a detection pulse is emitted, echo signals at different time t represent echoes at different depths in the tissue. In this embodiment, channels A and B emit detection pulses at a certain pulse repetition frequency to detect the displacement of vascular tissue and obtain a curve of the displacement versus time. The principle is similar to that of pulse Doppler.

Further, multiple detection pulses are transmitted at a certain pulse repetition frequency to obtain an echo sequence of detection pulses, and k represents the number of echo frames in the sequence. The amplitude and phase of the echo signal are modulated by the tissue vibration at this point, from which the phase change of the vascular tissue vibration can be extracted through a certain algorithm. In specific implementation, the radio frequency (RF) signal received from the detection vibration element is amplified by the ultrasonic front-end circuit, processed by analog-to-digital conversion, and then processed by quadrature demodulation to obtain the complex envelope of the RF signal. For a detection point, the complex envelope signals of the adjacent frames of the echo signal are cross-correlated, and the signals of tissue vibration in different depths of the point are extracted.

Calculate the phase of the vibration signal of the detection point at a certain depth, and subtract the phase of the adjacent frame from the phase of each frame to obtain the phase difference of each frame, and then obtain the displacement curve of the vascular tissue over time. For two detection points with a distance Z, the phase velocity c _L can be calculated from the displacement curves at a certain depth of the two detection points.

The ECG collection module 103 is used to trigger the ECG collection machine 106 to collect ECG signals.

The estimation module 108 is used to obtain the phase velocity of the instantaneous propagation of the strain wave according to the displacement of the blood vessel tissue in the skin of each channel obtained above after filtering the pulse wave velocity, and estimate the instantaneous viscoelastic coefficient of the blood vessel.

In this embodiment, the phase velocity of the vibration propagating at two points can be calculated based on the displacement versus time curves of the vascular tissue in the skin under channels A and B obtained above, and the viscoelastic coefficient of the blood vessel can be estimated through a mathematical model.

In this embodiment, based on the mathematical model f(c,ω,μ ₁ ,μ ₂ )=0, estimating the elastic coefficient μ ₁ and the viscosity coefficient μ ₂ is a typical model-based nonlinear parameter estimation problem, and nonlinear least squares Estimation method solves. The specific process is briefly described below:

i. Assume a set of initial values of <μ ₁ , μ ₂ >;

ii. Estimation of the phase velocity spectrum based on the "least squares criterion" which is:

iii. Calculate the estimated phase velocity spectrum The sum of squared errors between the measured phase velocity spectrum c _phase (ω) is expressed as:

iv. If α(μ ₁ ,μ ₂ ) does not reach the preset accuracy, update value, return to step ii;

Otherwise the computation stops and the resulting is the estimated value of the instantaneous viscoelastic coefficient of the blood vessel.

In the specific implementation, optimization algorithms such as iterative method or search method can be used to obtain the optimal estimate of <μ ₁ , μ ₂ >.

The registration module 109 is used for temporally registering the estimated instantaneous viscoelastic coefficient of the blood vessel with the collected ECG signal to obtain the elastic modulus and viscous modulus of the blood vessel at different moments in the cardiac cycle. in particular:

In this embodiment, under the cardiac cycle of about one second, the above-mentioned method is repeated to excite the blood vessel to vibrate and the echo signal is collected multiple times, and the collected ECG signal is registered in time, so as to obtain different moments in the cardiac cycle The elastic modulus and viscous modulus of the vessel.

Referring to FIG. 2 , it is a flow chart of a preferred embodiment of the method for detecting arterial viscoelasticity in the present invention.

Step S400, controlling the external vibrator 104 to vibrate at a certain frequency on the skin close to the blood vessel. Specifically, the main control unit 101 controls the external vibrator 104 to generate a certain frequency of vibration through the transmitting/receiving module 102, which acts on the blood vessel tissue under the external vibrator 104 to cause the vibration to propagate laterally to the surrounding.

Step S401, the multi-channel ultrasonic probe 105 transmits detection pulses to the skin, records the pulse-echo signal of the vascular tissue in the skin under each channel, calculates the displacement of the vascular tissue in the skin of each channel, and filters out the displacement At the same time, the ECG acquisition machine 106 starts to collect ECG signals. in particular:

The received echo signal r(t,k) of the detection pulse is expressed as a two-dimensional signal. Once a detection pulse is emitted, echo signals at different time t represent echoes at different depths in the tissue. In this embodiment, channels A and B emit detection pulses at a certain pulse repetition frequency to detect the displacement of vascular tissue and obtain a curve of the displacement versus time. The principle is similar to that of pulse Doppler.

Further, multiple detection pulses are transmitted at a certain pulse repetition frequency to obtain an echo sequence of detection pulses, and k represents the number of echo frames in the sequence. The amplitude and phase of the echo signal are modulated by the tissue vibration at this point, from which the phase change of the vascular tissue vibration can be extracted through a certain algorithm. In specific implementation, the radio frequency (RF) signal received from the detection vibration element is amplified by the ultrasonic front-end circuit, processed by analog-to-digital conversion, and then processed by quadrature demodulation to obtain the complex envelope of the RF signal. For a detection point, the complex envelope signals of the adjacent frames of the echo signal are cross-correlated, and the signals of tissue vibration in different depths of the point are extracted.

Calculate the phase of the vibration signal of the detection point at a certain depth, and subtract the phase of the adjacent frame from the phase of each frame to obtain the phase difference of each frame, and then obtain the displacement curve of the vascular tissue over time. For two detection points with a distance Z, the phase velocity c _L can be calculated from the displacement curves at a certain depth of the two detection points.

Step S402, according to the displacement of blood vessel tissue in the skin of each channel obtained above after filtering out the pulse wave velocity, the phase velocity of the instantaneous propagation of the strain wave is obtained, and the instantaneous viscoelastic coefficient of the blood vessel is estimated.

In this embodiment, the phase velocity of the vibration propagating at two points can be calculated based on the displacement versus time curves of the vascular tissue in the skin under channels A and B obtained above, and the viscoelastic coefficient of the blood vessel can be estimated through a mathematical model.

In this embodiment, based on the mathematical model f(c,ω,μ ₁ ,μ ₂ )=0, estimating the elastic coefficient μ ₁ and the viscosity coefficient μ ₂ is a typical model-based nonlinear parameter estimation problem, and nonlinear least squares Estimation algorithm solves. The specific process is briefly described below:

i. Assume a set of initial values of <μ ₁ , μ ₂ >;

ii. Estimation of the phase velocity spectrum based on the "least squares criterion" which is:

iii. Calculate the estimated phase velocity spectrum The sum of squared errors between the measured phase velocity spectrum c _phase (ω) is expressed as:

iv. If α(μ ₁ ,μ ₂ ) does not reach the preset accuracy, update value, return to step ii;

Otherwise the computation stops and the resulting is the estimated value of the instantaneous viscoelastic coefficient of the blood vessel.

In the specific implementation, optimization algorithms such as iterative method or search method can be used to obtain the optimal estimate of <μ ₁ , μ ₂ >.

In step S403, the estimated instantaneous viscoelastic coefficient of the blood vessel is time-registered with the collected ECG signal to obtain the elastic modulus and viscous modulus of the blood vessel at different times in the cardiac cycle. in particular:

In this embodiment, under the cardiac cycle of about one second, the above-mentioned method is repeated to excite the blood vessel to vibrate and the echo signal is collected multiple times, and the collected ECG signal is registered in time, so as to obtain different moments in the cardiac cycle The elastic modulus and viscous modulus of the vessel.

The present invention measures multiple times under the cardiac cycle. Because in the pulsating blood vessels, the blood pressure is changing, and the viscoelasticity will be different with different blood pressure. For example, like a rubber band, the hardness and elasticity will be different under tension and relaxation. Therefore, this embodiment performs multiple (≥10) measurements in a cardiac cycle of about one second to obtain instantaneous viscoelastic spectra at different moments in the cardiac cycle, which is of great significance for diagnosing human vascular lesions. In this embodiment, the pulse repetition frequency of the external element excitation is 10HZ, that is, one vibration every 0.1 second, and each vibration will emit a certain amount of detection pulses to detect the change of displacement with time, and obtain the viscoelastic coefficient of the blood vessel.

The system for detecting arterial viscoelasticity of the present invention can be an independent device, or can be used as an additional functional module loaded on an ordinary color ultrasound system. When it is used as an additional functional module, it only needs to load the external vibrator 104 and the ECG acquisition machine 106 on the ordinary color Doppler ultrasound system, which saves cost and is convenient and simple.

Although the present invention has been described with reference to the current preferred embodiments, those skilled in the art should understand that the above-mentioned preferred embodiments are only used to illustrate the present invention, and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and scope of principles shall be included in the protection scope of the present invention.

Claims (10)

1. one kind detection viscoelastic system of arteries, it is characterised in that the system includes main control computer and the master control is electromechanical Property connection transmit/receive module and electrocardiogram acquisition module, the outside oscillator being electrically connected with the transmit/receive module And ultrasonic probe, the electrocardiogram acquisition machine being electrically connected with the electrocardiogram acquisition module, the main control computer include processing module, Estimation module and registration module, wherein：

The transmit/receive module is used to control outside oscillator producing vibration on the skin of blood vessel under cardiac cycle；

The transmit/receive module is additionally operable to drive ultrasonic probe to skin transmitting detection pulse under cardiac cycle, and record is super The pulse echo signal of vascular tissue in skin under each passage of sonic probe；

The processing module is used for the pulse echo signal of vascular tissue in the skin under each passage according to above-mentioned record, meter The displacement for obtaining vascular tissue in the skin of each passage is calculated, and filters out the pulse wave velocity in the displacement；

The electrocardiogram acquisition module is used to trigger electrocardiogram acquisition machine collection electrocardiosignal under cardiac cycle；

The estimation module is used to filter out after pulse wave velocity vascular tissue in the skin of each passage according to obtained above Displacement, tries to achieve the phase velocity of the instant exposure of strain wave, estimates the instantaneous viscoelastic coefficient of blood vessel；

The registration module be used for by the instantaneous viscoelastic coefficient of the blood vessel of estimation with collection electrocardiosignal it is registering in time, Obtain under cardiac cycle the not modulus of elasticity of blood vessel, viscous modulus in the same time.

2. the system as claimed in claim 1, it is characterised in that the ultrasonic probe is popped one's head in for channel ultrasonic.

3. system as claimed in claim 2, it is characterised in that described processing module is used to calculate the skin for obtaining each passage The displacement of Fu Nei vascular tissues, be specially：

From the amplification and the processing of analog-to-digital conversion for detecting first ultrasonic front-end circuit of radiofrequency signal process received that shakes, then by just Demodulation process is handed over, the complex envelope of radiofrequency signal is obtained；

To a certain test point, cross correlation process is carried out to the complex envelope signal of echo-signal consecutive frame, the different depths of point are extracted The signal of tissue vibration in degree；

The phase of test point vibration signal in some depth is calculated, the phase of each frame subtracts the phase of consecutive frame, obtained The phase difference of each frame is obtained, and then obtains the displacement curve that vascular tissue changes over time, for two test points at a distance of Z, is led to The displacement curve for crossing a certain depth of two test points asks for phase velocity c_L。

4. system as claimed in claim 3, it is characterised in that described estimation module be based on Lamb wave mathematical modeling f (c, ω,μ₁,μ₂)=0, is specifically included：

I. assume<μ₁,μ₂>One group of initial value；

Ii. the estimation of phase velocity spectrum is obtained based on " criterion of least squares "I.e.：

$\hat{c}({\mathrm{\&mu;}}_1,{\mathrm{\&mu;}}_2,\mathrm{\&omega;})=\underset{C}{\min }\underset{\mathrm{\&omega;}}{\&Sigma;}|f(\hat{c},{\mathrm{\&mu;}}_1,{\mathrm{\&mu;}}_2,\mathrm{\&omega;}){|}^2;$

Iii. the phase velocity spectrum of estimation is calculatedWith actual measurement phase velocity spectrum c_phaseError sum of squares between (ω), is represented For：

$\mathrm{\&alpha;}({\mathrm{\&mu;}}_1,{\mathrm{\&mu;}}_2)=\underset{\mathrm{\&omega;}}{\&Sigma;}|c_{phase}\left(\mathrm{\&omega;}\right)-\hat{c}(\mathrm{\&mu;},\mathrm{\&omega;}){|}^2;$

If iv. α (μ₁,μ₂) default precision is not up to, updateValue, return the i-th i step；

Otherwise calculate and stop, gainedIt is the estimate of the instantaneous viscoelastic coefficient of blood vessel.

5. system as claimed in claim 4, it is characterised in that described registration module specifically for：

The instantaneous viscoelastic coefficient of the blood vessel of estimation is done registering in time with the electrocardiosignal gathered, to obtain cardiac cycle Under blood vessel elasticity modulus not in the same time and viscous modulus.

6. one kind detection viscoelastic method of arteries, it is characterised in that this method comprises the following steps：

A. outside oscillator is controlled to produce vibration on the skin of blood vessel；

B. the ultrasonic probe of multichannel is to skin transmitting detection pulse, and the pulse for recording vascular tissue in skin under each passage is returned Ripple signal, and calculate and obtain the displacement of vascular tissue in the skin of each passage, and filter out the pulse wave velocity in the displacement, Electrocardiogram acquisition machine starts to gather electrocardiosignal simultaneously；

C. according to the displacement obtained above for filtering out vascular tissue in the skin of each passage after pulse wave velocity, strain wave is tried to achieve Instant exposure phase velocity, estimate blood vessel instantaneous viscoelastic coefficient；

D. it is the instantaneous viscoelastic coefficient of the blood vessel of estimation and the electrocardiosignal gathered is registering in time, obtain under cardiac cycle The not modulus of elasticity and viscous modulus of blood vessel in the same time.

7. method as claimed in claim 6, it is characterised in that described step b includes：

From the amplification and the processing of analog-to-digital conversion for detecting first ultrasonic front-end circuit of radiofrequency signal process received that shakes, then by just Demodulation process is handed over, the complex envelope of radiofrequency signal is obtained；

To a certain test point, cross correlation process is carried out to the complex envelope signal of echo-signal consecutive frame, the different depths of point are extracted The signal of tissue vibration in degree；

The phase of test point vibration signal in some depth is calculated, the phase of each frame subtracts the phase of consecutive frame, obtained Each frame phase difference is obtained, and then obtains the displacement curve that vascular tissue changes over time, for two test points at a distance of Z, is passed through The displacement curve of a certain depth of two test points asks for phase velocity c_L。

8. method as claimed in claim 7, it is characterised in that this method also includes：

Within a cardiac cycle, step a is repeated to step c.

9. method as claimed in claim 8, it is characterised in that described step c idiographic flows include：

I. assume<μ₁,μ₂>One group of initial value；

Ii. the estimation of phase velocity spectrum is obtained based on " criterion of least squares "I.e.：

$\hat{c}({\mathrm{\&mu;}}_1,{\mathrm{\&mu;}}_2,\mathrm{\&omega;})=\underset{C}{\min }\underset{\mathrm{\&omega;}}{\&Sigma;}|f(\hat{c},{\mathrm{\&mu;}}_1,{\mathrm{\&mu;}}_2,\mathrm{\&omega;}){|}^2;$

Iii. the phase velocity spectrum of estimation is calculatedWith actual measurement phase velocity spectrum c_phaseError sum of squares between (ω), is represented For：

$\mathrm{\&alpha;}({\mathrm{\&mu;}}_1,{\mathrm{\&mu;}}_2)=\underset{\mathrm{\&omega;}}{\&Sigma;}|c_{phase}\left(\mathrm{\&omega;}\right)-\hat{c}(\mathrm{\&mu;},\mathrm{\&omega;}){|}^2;$

If iv. α (μ₁,μ₂) default precision is not up to, updateValue, return the i-th i step；

Otherwise calculate and stop, gainedIt is the estimate of the instantaneous viscoelastic coefficient of blood vessel.

10. method as claimed in claim 9, it is characterised in that described step d is specifically included：

The instantaneous viscoelastic coefficient of the blood vessel of estimation is done registering in time with the electrocardiosignal gathered, it is aroused in interest to obtain one Blood vessel elasticity modulus not in the same time and viscous modulus in cycle.