CN105844645A - Instantaneous elasticity imaging code detection method and system - Google Patents

Abstract

The present invention discloses an instantaneous elasticity imaging code detection method and a system. The method comprises the steps: an instantaneous low-frequency signal sent by a signal generator is subjected to power amplification to drive an electromagnetic vibrator and motivate the generation of an instantaneous shear wave inside a medium; modulating the coding of an ultrasonic pulse signal, detecting and tracking the vibration signal of the instantaneous shear wave based on the coded excitation technique to obtain a coded ultrasonic echo signal; amplifying and sampling the received coded ultrasonic echo signal to obtain coded detection echo discrete data; decoding according to the digital pulse compression technique to obtain a vibration displacement signal generated during the propagating process of the shear wave in a to-be-detected medium; according to the extracted displacement signal, calculating the speed of the instantaneous shear wave and the elastic modulus of the to-be-detected medium; and outputting the speed of the instantaneous shear wave and the elastic modulus of the to-be-detected medium. According to the technical scheme of the invention, the average emission energy of signals is improved, and the signal-to-noise ratio of echo signals is increased. Meanwhile, the system detection sensitivity and the ultrasonic penetration capability are improved. Moreover, the vibration signal extraction quality of the shear wave is improved, and the depth-detection penetrating power of the instantaneous elasticity imaging process is enhanced.

Description

A kind of Transient elastography code detection method and system

Technical field

The present invention relates to elastography field, particularly relate to a kind of Transient elastography code detection Method and system.

Background technology

Transient elastography technology provides a kind of quick, succinct, noinvasive and the most painless liver is hard Degree detection method, its principle is mainly by measuring low frequency shear waves spread speed in hepatic tissue fiber Judge the hardness of liver, thus evaluate the degree of hepatic fibrosis.ECHOSENS company of France Have VCTE (vibration control instantaneous elasticity) the liver hardness noinvasive being specifically designed to FibroScan equipment Quantitative Diagnosis patented technology, this Transient elastography technology main device is to be fixed on by ultrasonic transducer On electromagnetic vibrator, electromagnetic vibrator produces low frequency instant vibration, drives ultrasound transducer probe itself Produce temporary impact on viscoelastic medium surface, thus produce shearing wave at organization internal.Utilize ultrasonic Impulse echo technique, uses conventional short pulse mode to keep track of instantaneous shearing wave the most in time Communication process.By the analysis to ultrasonic M-mode signal, determine instantaneous shearing wave in the tissue Spread speed, thus the elastic modelling quantity of computation organization.

The signal to noise ratio of ultrasound echo signal determines the extraction quality of shearing wave signal.Ultrasound wave is at human body In decay with propagation distance exponentially, the ultrasonic signal returned from probe target farther out is the most weak, is subject to Noise jamming is serious, causes the signal to noise ratio of depths echo-signal to reduce.Ultrasonic propagation in fatty tissue Decay even more serious, therefore in Transient elastography clinical practice, for adiposis patient, ultrasonic letter Number decay cause being difficult to that depth location shearing wave is propagated the microtissue vibration signal that causes and carry Taking, this Technological expression goes out to detect the phenomenon that penetration power is inadequate, it is difficult to realize accurately detection.

Therefore, prior art has yet to be improved and developed.

Summary of the invention

In view of the deficiencies in the prior art, present invention aim at providing a kind of Transient elastography coding inspection Survey method and system, it is intended to solve the decay of ultrasonic signal in prior art and cause being difficult to depth location Shearing wave is propagated the microtissue vibration signal signal caused and is extracted, and detects inadequate the showing of penetration power As, it is difficult to realize the defect of accurately detection.

Technical scheme is as follows:

A kind of Transient elastography code detection method, wherein, method includes:

The instantaneous low frequency signal that A, signal generator send is through power amplification rear drive electromagnetic vibrator, electricity Magnetic vibrator drives probe impact testing medium surface, and excitable media is internal produces instantaneous shearing wave；

B, ultrasonic pulsative signal is carried out coded modulation, utilize coding signal to drive ultrasonic transducer, adopt By code-excited technology, instantaneous shearing wave vibration signal carried out detect and track, and it is ultrasonic to obtain coding Echo-signal；

C, to receive coding ultrasound echo signal be amplified and sample, obtain code detection and return Ripple discrete data；

D, being decoded code detection echo discrete data according to Digital Pulse Compression Technique, acquisition is cut Cut ripple in detected medium, propagate the vibration displacement signal caused；

E, calculate instantaneous shear wave velocity and the elastic modelling quantity of detected medium according to the displacement signal extracted And export.

Described Transient elastography code detection method, wherein, described step B specifically includes:

B1, the instantaneous low frequency signal of acquisition signal generator；

B2, utilization coding signal drive ultrasonic transducer, use code-excited technology to instantaneous shearing wave Vibration signal carries out detect and track；

B3, obtain to instantaneous shearing wave vibration signal follow the tracks of after coding ultrasound echo signal.

Described Transient elastography code detection method, wherein, described step D specifically includes:

D1, according to Digital Pulse Compression Technique, code detection echo discrete data is decoded, decoding After ultrasound echo signal y (d) be:

$y\left(d\right)=\underset{i=1}{\overset{m}{\Σ}}c\left(i\right)x(d+i-1)$

D is sampling depth serial number, and x (d) is coding ultrasonic echo discrete signal, and c (i) is corresponding transmitting The sequence of symhols of pulse, m is the data length of code；

D2, Mutual spectrum is utilized to extract shearing wave Jie to be detected according to decoded ultrasound echo signal Matter is propagated the vibration displacement signal caused.

Described Transient elastography code detection method, wherein, described step D2 specifically includes:

D21, obtain decoded ultrasound echo signal, if the echo-signal of n-th frame and the (n+1)th frame is divided Not Wei s (n) and s (n+1), its corresponding frequency spectrum is S_n(f) and S_n+1(f), cross-spectrum is expressed as:

$S_n^{*}\left(f\right)S_{n+1}\left(f\right)=\left|S_n\left(f\right)\right|\left|S_{n+1}\left(f\right)\right|e^{{\mathrm{j\Δ\θ}}_n\left(f\right)}$

Wherein Δ θ_nF () is the phase shift that adjacent twice ultrasonic echo that scattering son motion causes produces；

D22, utilize the phase shift of cross-spectrum peak frequency composition be scattered sub-vibration velocity extract, scattering son Vibration velocity v_nParticularly as follows:

v_n=c. Δ θ_n(f_max)/4πf_maxT_prf

Wherein f_maxIt is peak frequency composition in cross-spectrum, T_prfFor coding ultrasonic pulse repetition rate, c is super SVEL；

D23, scattering are at the displacement d of the (n+1)th frame_n+1For:

$d_{n+1}=d_0+\underset{1}{\overset{n}{\Σ}}{v}_n{T}_{prf}$

Wherein scatter sub-initial displacement and be designated as d₀。

A kind of Transient elastography code detection system, wherein, system includes:

Shearing wave generation module, the instantaneous low frequency signal sent for signal generator is after power amplification Driving electromagnetic vibrator, electromagnetic vibrator drives probe impact testing medium surface, inside excitable media Produce instantaneous shearing wave；

Coding module, for ultrasonic pulsative signal carries out coded modulation, utilizes coding signal to drive super Sonic transducer, uses code-excited technology that instantaneous shearing wave vibration signal is carried out detect and track, and Obtain coding ultrasound echo signal；

Sampling module, for the coding ultrasound echo signal received is amplified and samples, To code detection echo discrete data；

Decoding with signal extraction module, for according to Digital Pulse Compression Technique to code detection echo from Dissipate decoding data, obtain shearing wave in detected medium, propagate the vibration displacement signal caused；

Calculate and output module, for calculating instantaneous shear wave velocity according to the displacement signal extracted and treating Detect the elastic modelling quantity of medium and export.

Described Transient elastography code detection system, wherein, described coding module specifically includes:

First signal acquiring unit, for obtaining the instantaneous low frequency signal of signal generator；

Coding unit, is used for utilizing coding signal to drive ultrasonic transducer, uses code-excited technology pair Instantaneous shearing wave vibration signal carries out detect and track；

Secondary signal acquiring unit, for obtain to instantaneous shearing wave vibration signal follow the tracks of after coding Ultrasound echo signal.

Described Transient elastography code detection system, wherein, described decoding and signal extraction module Specifically include:

Ultrasound echo signal decoding unit, is used for according to Digital Pulse Compression Technique code detection echo Discrete data is decoded, and decoded ultrasound echo signal y (d) is:

$y\left(d\right)=\underset{i=1}{\overset{m}{\Σ}}c\left(i\right)x(d+i-1)$

D is sampling depth serial number, and x (d) is coding ultrasonic echo discrete signal, and c (i) is corresponding transmitting The sequence of symhols of pulse, m is the data length of code；

Vibration displacement extraction unit, for utilizing Mutual spectrum to extract according to decoded ultrasound echo signal Go out shearing wave in detected medium, propagate the vibration displacement signal caused.

Described Transient elastography code detection system, wherein, described vibration displacement extraction unit has Body includes:

Echo-signal cross-spectrum computing unit, is used for obtaining decoded ultrasound echo signal, if n-th frame and The echo-signal of the (n+1)th frame is respectively s (n) and s (n+1), and its corresponding frequency spectrum is S_n(f) and S_n+1(f), mutually Stave is shown as:

$S_n^{*}\left(f\right)S_{n+1}\left(f\right)=\left|S_n\left(f\right)\right|\left|S_{n+1}\left(f\right)\right|e^{{\mathrm{j\Δ\θ}}_n\left(f\right)}$

Wherein Δ θ_nF () is the phase shift that adjacent twice ultrasonic echo that scattering son motion causes produces；

Vibration velocity calculates unit, shakes for utilizing the phase shift of cross-spectrum peak frequency composition to be scattered son Dynamic VELOCITY EXTRACTION, scatters sub-vibration velocity v_nParticularly as follows:

v_n=c. Δ θ_n(f_max)/4πf_maxT_prf

Wherein f_maxIt is peak frequency composition in cross-spectrum, T_prfFor coding ultrasonic pulse repetition rate, c is super SVEL；

Displacement computing unit, for scattering the son displacement d at the (n+1)th frame_n+1For:

$d_{n+1}=d_0+\underset{1}{\overset{n}{\Σ}}{v}_n{T}_{prf}$

Wherein scatter sub-initial displacement and be designated as d₀。

The invention provides a kind of Transient elastography code detection method and system, the present invention is not increasing On the premise of adding the instantaneous power of transmitting signal, while keeping detection resolution, improve the flat of signal All emitted energies, improve the signal to noise ratio of echo-signal, the detection sensitivity of system and ultrasonic penetration ability. The detection sensitivity of simultaneity factor is corresponding with the raising of ultrasonic penetration ability improve tissue depth small The power of test of vibration signal, thus improve the extraction quality to shearing wave vibration signal, improve wink Time the inadequate problem of elastogram degree of depth penetration power, improve Transient elastography detection robustness.

Accompanying drawing explanation

Fig. 1 is the flow process of the preferred embodiment of a kind of Transient elastography code detection method in the present invention Figure.

Fig. 2 is the Transient elastography device schematic diagram of the present invention.

Fig. 3 a is the effect schematic diagram that shearing wave signal uses existing pulse detection.

Fig. 3 b is the effect schematic diagram of the coded pulse detection that shearing wave signal uses the present invention.

Fig. 4 is the function of the preferred embodiment of a kind of Transient elastography code detection system of the present invention Theory diagram.

Detailed description of the invention

For making the purpose of the present invention, technical scheme and effect clearer, clear and definite, below to the present invention Further describe.Should be appreciated that specific embodiment described herein is only in order to explain this Bright, it is not intended to limit the present invention.

Present invention also offers the flow process of the preferred embodiment of a kind of Transient elastography code detection method Figure, as shown in Figure 1 and Figure 2,1 is wherein electromagnetic vibrator in Fig. 2, and 2 is instantaneous low frequency signal, 3 is probe, and 4 is coding ultrasound echo signal, and 5 is testing medium.Wherein, method includes:

The instantaneous low frequency signal 2 that step S100, signal generator send is through power amplification rear drive electromagnetism Vibrator 1, electromagnetic vibrator 1 drives probe 3 impact testing medium 5 surface, and excitable media is internal to be produced Raw instantaneous shearing wave；

Step S200, the coded modulation that carries out ultrasonic pulsative signal, utilize coding signal to drive ultrasonic changing Energy device, uses code-excited technology that instantaneous shearing wave vibration signal is carried out detect and track, and obtains Coding ultrasound echo signal 4；

Step S300, to receive coding ultrasound echo signal 4 be amplified and sample, obtain Code detection echo discrete data；

Step S400, according to Digital Pulse Compression Technique, code detection echo discrete data is decoded, Obtain shearing wave in detected medium, propagate the vibration displacement signal caused；

Step S500, calculate instantaneous shear wave velocity and detected medium according to the displacement signal extracted Elastic modelling quantity also exports.

When being embodied as, in described step S100, signal generator sends instantaneous low frequency signal, and low frequency is believed Number frequency range be: 50～200Hz, and instantaneous low frequency signal drives electromagnetic vibration through power amplifier Dynamic device, vibrator drives and ties up the ultrasonic probe temporary impact dielectric surface on its axle, at organization internal Produce shearing wave.

Ultrasonic transducer encoded excitation signal is kept Tong Bu with low frequency drive signal by described step S200, So easily realize the detect and track to shearing wave communication process.

In described step S300, coded echo signal is amplified (scope-1V arrives+1V) through preliminary, Directly carry out A/D sampling, complete the digitized of code detection echo-signal.

Described step S400 is propagated due to shearing wave in testing medium, testing medium can be caused to shake. The present invention is with testing medium for tissue.

In described step S500, after tissue vibration displacement signal has extracted, first to tissue vibrations Displacement signal FFT process, extracts the mid frequency f of each degree of depth shearing wave₀The phase of the shearing wave at place Position, this process can be expressed as:To the shearing wave phase in the range of certain depth Position carries out linear fit, and shearing wave has a Phase delay between the tissue of different depth, it is assumed that certain One degree of depth Z₂Relative to degree of depth Z₁Phase delay beThen the mean propagation velocity C of shearing wave_sCan To be expressed as:

If tissue approximations such as livers as non-sticky, isotropic line elastomer, then it is elastic Modulus can be expressed as with the spread speed theory relation of shearing wave:Wherein, ρ represents liver The density of tissue, thus can calculate the average elastic modulus E of hepatic tissue, represent with kPa.

Further carrying out in example, step S200 specifically includes:

Step S201, the instantaneous low frequency signal of acquisition signal generator；

Step S202, utilization coding signal drive ultrasonic transducer, use code-excited technology to instantaneous Shearing wave vibration signal carries out detect and track；

Step S203, obtain to instantaneous shearing wave vibration signal follow the tracks of after coding ultrasound echo signal.

When being embodied as, encode signal, it is not limited to phase code, the most other coded system, As to frequency coding etc..It is introduced as a example by phase code.The generation of phase code pumping signal is real Be exactly the process of a secondary modulation on border, will carry out the transmitting signal of carrier modulation, then with code Sheet is multiplied.The selection of this chip is based on to system bandwidth resource, the complexity that system hardware realizes Degree, and considering of carrying out of the performance of decoding filter and pulse compression.Encoded excitation signal leads to Overdrive circuit deactivates ultrasonic transducer, in the way of pulse echo, through T/R switch module, Receive and obtain the ultrasound echo signal propagating information containing shearing wave.

Further embodiment, described step S400 specifically includes:

Step S401, according to Digital Pulse Compression Technique, code detection echo discrete data is decoded, Decoded ultrasound echo signal y (d) is:

$y\left(d\right)=\underset{i=1}{\overset{m}{\Σ}}c\left(i\right)x(d+i-1)$

D is sampling depth serial number, and x (d) is coding ultrasonic echo discrete signal, and c (i) is corresponding transmitting The sequence of symhols of pulse, m is the data length of code；

Step S402, utilize Mutual spectrum to extract shearing wave to treat according to decoded ultrasound echo signal The vibration displacement signal that detection Propagation causes.

When being embodied as, owing to echo-signal directly to have been carried out digitized processing, the most here may be used The decoding of signal is realized with Applied Digital pulse compression technique very easily.According to coding theory, solve Code device should be an autocorrelative process, and it can be expressed from the next:

$y\left(d\right)=\underset{i=1}{\overset{m}{\Σ}}c\left(i\right)x(d+i-1)$

D is sampling depth serial number, and y (d) is the ultrasound echo signal after decoding, and x (d) is to compile Code impulse ultrasound echo-signal, c (i) is corresponding exomonental sequence of symhols, and m is the data length of code.

When being embodied as, step S402 specifically includes:

Step S421, obtain decoded ultrasound echo signal, if the echo letter of n-th frame and the (n+1)th frame Number being respectively s (n) and s (n+1), its corresponding frequency spectrum is S_n(f) and S_n+1(f), cross-spectrum is expressed as:

$S_n^{*}\left(f\right)S_{n+1}\left(f\right)=\left|S_n\left(f\right)\right|\left|S_{n+1}\left(f\right)\right|e^{{\mathrm{j\Δ\θ}}_n\left(f\right)}$

Wherein Δ θ_nF () is the phase shift that adjacent twice ultrasonic echo that scattering son motion causes produces；

Step S422, utilize the phase shift of cross-spectrum peak frequency composition be scattered sub-vibration velocity extract, Scatter sub-vibration velocity v_nParticularly as follows:

v_n=c. Δ θ_n(f_max)/4πf_maxT_prf

Wherein f_maxIt is peak frequency composition in cross-spectrum, T_prfFor coding ultrasonic pulse repetition rate, c is super SVEL；

Step S423, scattering are at the displacement d of the (n+1)th frame_n+1For:

$d_{n+1}=d_0+\underset{1}{\overset{n}{\Σ}}{v}_n{T}_{prf}$

Wherein scatter sub-initial displacement and be designated as d₀。

When being embodied as, ultrasonic velocity is preferably 1540m/s.Echo-signal after utilizing decoding is entered Row tissue vibration displacement signal extracts.Displacement Estimation based on ultrasonic method can use cross-correlation or phase shift Algorithm realizes, though cross-correlation method can accurately estimate displacement, but computationally intensive, and phase shift is calculated Although method accuracy is high, but be not suitable for the estimation of larger displacement, therefore, in this code detection method Using mutual spectral method to realize Displacement Estimation, the method has advantage stable, quick and accurate.If the The echo-signal of n frame and the (n+1)th frame is respectively s (n) and s (n+1), and its corresponding frequency spectrum is S_n(f) and S_n+1F (), cross-spectrum can be able to obtain by its frequency spectrum is carried out conjugate multiplication computing, and this process is expressed Formula is:

$S_n^{*}\left(f\right)S_{n+1}\left(f\right)=\left|S_n\left(f\right)\right|\left|S_{n+1}\left(f\right)\right|e^{{\mathrm{j\Δ\θ}}_n\left(f\right)}$

Wherein Δ θ_nF () is the phase shift that the scattering son adjacent twice return that causes of motion produces, utilize cross-spectrum The phase shift of big frequency content is scattered sub-vibration velocity and extracts, and this process is expressed as: v_n=c. Δ θ_n(f_max)/4πf_maxT_prf, wherein f_maxPeak frequency composition in cross-spectrum, the most adaptively selected can To reduce vibration signal estimated bias.T_prfFor coding ultrasonic pulse repetition rate.If scattering sub-initial bit Move as d₀, then scattering is at the displacement d of the (n+1)th frame_n+1 is:Complete vibration displacement Signal extraction.

Citing: as a example by 7 Barker code code detection, pulse detecting method short with routine contrasts, The inventive method is described further:

Shown in Fig. 3 a and Fig. 3 b: under the conditions of identical transient vibration voltage drive, be respectively adopted short The shearing wave signal that transient vibration is produced by pulse mode and Barker code coded system carries out detect and track. Contrast easily finds, under the conditions of identical voltage drive, code detection can well suppress noise, Improve shearing wave signal to noise ratio, and then improve Transient elastography detection penetration power, and improve instantaneous elasticity The robustness of detection.

The present invention is not only limited to 7 Barker codes, it is also possible to select to use the Bark of other different length Code, and the encoding scheme such as linear frequency modulation code, pseudo noise code still belongs to this invention scope.

From above method embodiment, the invention provides a kind of Transient elastography code detection side Method, in Transient elastography, uses code-excited technology that shearing wave signal is carried out detect and track (the short pulse detection of routine different from the past), while keeping detection resolution, improves ultrasonic time The signal to noise ratio of ripple signal, increases the investigation depth of ultrasonic signal, improves shearing small to tissue depth The power of test of ripple vibration signal, improves shearing wave signal to noise ratio, thus adds somewhat to instantaneous The penetration depth of elastogram detection, and improve the robustness of instantaneous elasticity detection.

Present invention also offers the function of the preferred embodiment of a kind of Transient elastography code detection system Theory diagram, as shown in Figure 4, wherein, system includes:

Shearing wave generation module 100, the instantaneous low frequency signal sent for signal generator is through power amplification Rear drive electromagnetic vibrator, electromagnetic vibrator drives probe impact testing medium surface, in excitable media Portion produces instantaneous shearing wave；Described in concrete as above embodiment of the method.

Coding module 200, for ultrasonic pulsative signal carries out coded modulation, utilizes coding signal to drive Ultrasonic transducer, uses code-excited technology that instantaneous shearing wave vibration signal is carried out detect and track, And obtain coding ultrasound echo signal；Described in concrete as above embodiment of the method.

Sampling module 300, for the coding ultrasound echo signal received is amplified and samples, Obtain code detection echo discrete data；Described in concrete as above embodiment of the method.

Decoding and signal extraction module 400, be used for according to Digital Pulse Compression Technique code detection echo Discrete data is decoded, and obtains shearing wave and propagates the vibration displacement signal caused in detected medium； Described in concrete as above embodiment of the method.

Calculate with output module 500, for according to extract displacement signal calculate instantaneous shear wave velocity and The elastic modelling quantity of detected medium also exports；Described in concrete as above embodiment of the method.

Described Transient elastography code detection system, wherein, described coding module specifically includes:

First signal acquiring unit, for obtaining the instantaneous low frequency signal of signal generator；The most as above Described in embodiment of the method.

Coding unit, is used for utilizing coding signal to drive ultrasonic transducer, uses code-excited technology pair Instantaneous shearing wave vibration signal carries out detect and track；Described in concrete as above embodiment of the method.

Secondary signal acquiring unit, for obtain to instantaneous shearing wave vibration signal follow the tracks of after coding Ultrasound echo signal；Described in concrete as above embodiment of the method.

Described Transient elastography code detection system, wherein, described decoding and signal extraction module Specifically include:

Ultrasound echo signal decoding unit, is used for according to Digital Pulse Compression Technique code detection echo Discrete data is decoded, and decoded ultrasound echo signal y (d) is:

$y\left(d\right)=\underset{i=1}{\overset{m}{\Σ}}c\left(i\right)x(d+i-1)$

D is sampling depth serial number, and x (d) is coding ultrasonic echo discrete signal, and c (i) is corresponding transmitting The sequence of symhols of pulse, m is the data length of code；Described in concrete as above embodiment of the method.

Vibration displacement extraction unit, for utilizing Mutual spectrum to extract according to decoded ultrasound echo signal Go out shearing wave in detected medium, propagate the vibration displacement signal caused；Concrete as above embodiment of the method Described.

Described Transient elastography code detection system, wherein, described vibration displacement extraction unit has Body includes:

Echo-signal cross-spectrum computing unit, is used for obtaining decoded ultrasound echo signal, if n-th frame and The echo-signal of the (n+1)th frame is respectively s (n) and s (n+1), and its corresponding frequency spectrum is S_n(f) and S_n+1(f), mutually Stave is shown as:

$S_n^{*}\left(f\right)S_{n+1}\left(f\right)=\left|S_n\left(f\right)\right|\left|S_{n+1}\left(f\right)\right|e^{{\mathrm{j\Δ\θ}}_n\left(f\right)}$

Wherein Δ θ_nF () is the phase shift that adjacent twice ultrasonic echo that scattering son motion causes produces；The most such as Described in upper embodiment of the method.

Vibration velocity calculates unit, shakes for utilizing the phase shift of cross-spectrum peak frequency composition to be scattered son Dynamic VELOCITY EXTRACTION, scatters sub-vibration velocity v_nParticularly as follows:

v_n=c. Δ θ_n(f_max)/4πf_maxT_prf

Wherein f_maxIt is peak frequency composition in cross-spectrum, T_prfFor coding ultrasonic pulse repetition rate, c is super SVEL；Described in concrete as above embodiment of the method

Displacement computing unit, for scattering the son displacement d at the (n+1)th frame_n+1For:

$d_{n+1}=d_0+\underset{1}{\overset{n}{\Σ}}{v}_n{T}_{prf}$

Wherein scatter sub-initial displacement and be designated as d₀；Described in concrete as above embodiment of the method.

In sum, the invention provides a kind of Transient elastography code detection method and system, side Method includes: the instantaneous low frequency signal that signal generator sends through power amplification rear drive electromagnetic vibrator, Excitable media is internal produces instantaneous shearing wave；Ultrasonic pulsative signal is carried out coded modulation, utilizes coding Signal drives ultrasonic transducer, uses code-excited technology to detect instantaneous shearing wave vibration signal And tracking, obtain coding ultrasound echo signal；The coding ultrasound echo signal received is amplified also Sampling, obtains code detection echo discrete data；According to Digital Pulse Compression Technique, code detection is returned Ripple discrete data is decoded, and obtains shearing wave and propagates the vibration displacement letter caused in detected medium Number；The elastic modelling quantity of instantaneous shear wave velocity and detected medium is calculated also according to the displacement signal extracted Output.The present invention can improve the average transmission energy of signal, improves the signal to noise ratio of echo-signal, system Detection sensitivity and ultrasonic penetration ability, thus improve extraction quality to shearing wave vibration signal, Improve Transient elastography depth detection penetration power, improve Transient elastography detection robustness.

It should be appreciated that the application of the present invention is not limited to above-mentioned citing, to ordinary skill For personnel, can be improved according to the above description or convert, all these modifications and variations are all answered Belong to the protection domain of claims of the present invention.

Claims (8)

1. a Transient elastography code detection method, it is characterised in that method includes:

The instantaneous low frequency signal that A, signal generator send is through power amplification rear drive electromagnetic vibrator, electricity Magnetic vibrator drives probe impact testing medium surface, and excitable media is internal produces instantaneous shearing wave；

B, ultrasonic pulsative signal is carried out coded modulation, utilize coding signal to drive ultrasonic transducer, adopt By code-excited technology, instantaneous shearing wave vibration signal carried out detect and track, and it is ultrasonic to obtain coding Echo-signal；

C, to receive coding ultrasound echo signal be amplified and sample, obtain code detection and return Ripple discrete data；

D, being decoded code detection echo discrete data according to Digital Pulse Compression Technique, acquisition is cut Cut ripple in detected medium, propagate the vibration displacement signal caused；

E, calculate instantaneous shear wave velocity and the elastic modelling quantity of detected medium according to the displacement signal extracted And export.

Transient elastography code detection method the most according to claim 1, it is characterised in that Described step B specifically includes:

B1, the instantaneous low frequency signal of acquisition signal generator；

B2, utilization coding signal drive ultrasonic transducer, use code-excited technology to instantaneous shearing wave Vibration signal carries out detect and track；

B3, obtain to instantaneous shearing wave vibration signal follow the tracks of after coding ultrasound echo signal.

Transient elastography code detection method the most according to claim 2, it is characterised in that Described step D specifically includes:

D1, according to Digital Pulse Compression Technique, code detection echo discrete data is decoded, decoding After ultrasound echo signal y (d) be:

$y\left(d\right)=\underset{i=1}{\overset{m}{\Σ}}c\left(i\right)x(d+i-1)$

D is sampling depth serial number, and x (d) is coding ultrasonic echo discrete signal, and c (i) is corresponding transmitting The sequence of symhols of pulse, m is the data length of code；

D2, Mutual spectrum is utilized to extract shearing wave Jie to be detected according to decoded ultrasound echo signal Matter is propagated the vibration displacement signal caused.

Transient elastography code detection method the most according to claim 3, it is characterised in that Described step D2 specifically includes:

D21, obtain decoded ultrasound echo signal, if the echo-signal of n-th frame and the (n+1)th frame is divided Not Wei s (n) and s (n+1), its corresponding frequency spectrum is S_n(f) and S_n+1(f), cross-spectrum is expressed as:

$S_n^{*}\left(f\right)S_{n+1}\left(f\right)=\left|S_n\left(f\right)\right|\left|S_{n+1}\left(f\right)\right|e^{{\mathrm{j\Δ\θ}}_n\left(f\right)}$

Wherein Δ θ_nF () is the phase shift that adjacent twice ultrasonic echo that scattering son motion causes produces；

D22, utilize the phase shift of cross-spectrum peak frequency composition be scattered sub-vibration velocity extract, scattering son Vibration velocity v_nParticularly as follows:

v_n=c. Δ θ_n(f_max)/4πf_maxT_prf

Wherein f_maxIt is peak frequency composition in cross-spectrum, T_prfFor coding ultrasonic pulse repetition rate, c is super SVEL；

D23, scattering are at the displacement d of the (n+1)th frame_n+1For:

$d_{n+1}=d_0+\underset{1}{\overset{n}{\Σ}}{v}_n{T}_{prf}$

Wherein scatter sub-initial displacement and be designated as d₀。

5. a Transient elastography code detection system, it is characterised in that system includes:

Shearing wave generation module, the instantaneous low frequency signal sent for signal generator is after power amplification Driving electromagnetic vibrator, electromagnetic vibrator drives probe impact testing medium surface, inside excitable media Produce instantaneous shearing wave；

Coding module, for ultrasonic pulsative signal carries out coded modulation, utilizes coding signal to drive super Sonic transducer, uses code-excited technology that instantaneous shearing wave vibration signal is carried out detect and track, and Obtain coding ultrasound echo signal；

Sampling module, for the coding ultrasound echo signal received is amplified and samples, To code detection echo discrete data；

Decoding with signal extraction module, for according to Digital Pulse Compression Technique to code detection echo from Dissipate decoding data, obtain shearing wave in detected medium, propagate the vibration displacement signal caused；

Calculate and output module, for calculating instantaneous shear wave velocity according to the displacement signal extracted and treating Detect the elastic modelling quantity of medium and export.

Transient elastography code detection system the most according to claim 5, it is characterised in that Described coding module specifically includes:

First signal acquiring unit, for obtaining the instantaneous low frequency signal of signal generator；

Coding unit, is used for utilizing coding signal to drive ultrasonic transducer, uses code-excited technology pair Instantaneous shearing wave vibration signal carries out detect and track；

Secondary signal acquiring unit, for obtain to instantaneous shearing wave vibration signal follow the tracks of after coding Ultrasound echo signal.

Transient elastography code detection system the most according to claim 6, it is characterised in that Described decoding specifically includes with signal extraction module:

Ultrasound echo signal decoding unit, is used for according to Digital Pulse Compression Technique code detection echo Discrete data is decoded, and decoded ultrasound echo signal y (d) is:

$y\left(d\right)=\underset{i=1}{\overset{m}{\Σ}}c\left(i\right)x(d+i-1)$

D is sampling depth serial number, and x (d) is coding ultrasonic echo discrete signal, and c (i) is corresponding transmitting The sequence of symhols of pulse, m is the data length of code；

Vibration displacement extraction unit, for utilizing Mutual spectrum to extract according to decoded ultrasound echo signal Go out shearing wave in detected medium, propagate the vibration displacement signal caused.

Transient elastography code detection system the most according to claim 7, it is characterised in that Described vibration displacement extraction unit specifically includes:

Echo-signal cross-spectrum computing unit, is used for obtaining decoded ultrasound echo signal, if n-th frame and The echo-signal of the (n+1)th frame is respectively s (n) and s (n+1), and its corresponding frequency spectrum is S_n(f) and S_n+1(f), mutually Stave is shown as:

$S_n^{*}\left(f\right)S_{n+1}\left(f\right)=\left|S_n\left(f\right)\right|\left|S_{n+1}\left(f\right)\right|e^{{\mathrm{j\Δ\θ}}_n\left(f\right)}$

Wherein Δ θ_nF () is the phase shift that adjacent twice ultrasonic echo that scattering son motion causes produces；

Vibration velocity calculates unit, shakes for utilizing the phase shift of cross-spectrum peak frequency composition to be scattered son Dynamic VELOCITY EXTRACTION, scatters sub-vibration velocity v_nParticularly as follows:

v_n=c. Δ θ_n(f_max)/4πf_maxT_prf

Wherein f_maxIt is peak frequency composition in cross-spectrum, T_prfFor coding ultrasonic pulse repetition rate, c is super SVEL；

Displacement computing unit, for scattering the son displacement d at the (n+1)th frame_n+1For:

$d_{n+1}=d_0+\underset{1}{\overset{n}{\Σ}}{v}_n{T}_{prf}$

Wherein scatter sub-initial displacement and be designated as d₀。