Ultrasonic vector Doppler imaging method, device, equipment, medium and product

Abstract

The invention discloses an ultrasonic vector Doppler imaging method, device and equipment, a medium and a product, and relates to the field of vector Doppler imaging, and the method comprises the steps: employing a gating time window to carry out the interception of an overall echo signal corresponding to each transmitting corner, and obtaining a radio frequency signal; obtaining an in-phase orthogonal signal and an average value of a center frequency according to the radio frequency signal after coherent combination; obtaining an axial speed according to the average value and a result obtained by carrying out self-correlation estimation on the in-phase orthogonal signal; according to the average value and a result obtained by performing autocorrelation estimation on the first beam signal and the second beam signal, obtaining axial speeds at the two preset angles; processing the axial speeds at the two preset angles by adopting an improved vector Doppler algorithm to obtain a speed vector; and generating an image according to the in-phase orthogonal signal, the axial speed and the speed vector. The method can further improve the accuracy of a speed vector result measured by an ultrasonic vector Doppler imaging technology.

Description

Technical Field

[0001] The present application relates to the field of vector Doppler imaging, and particularly to an ultrasonic vector Doppler imaging method, device, equipment, medium and product. Background Art

[0002] At present, the measurement techniques for blood flow velocity distribution in clinical practice include techniques such as magnetic resonance imaging, laser Doppler imaging, CT angiography, and ultrasonic vector Doppler imaging. Magnetic resonance imaging can provide high-resolution three-dimensional blood flow imaging and rich anatomical and functional information, but the equipment is expensive and the scanning time is long; laser Doppler imaging is suitable for high-precision microcirculation blood flow monitoring, but the measurement depth is limited and it is mainly used for superficial tissues; CT angiography can quickly generate three-dimensional vascular imaging and is suitable for emergency and preoperative evaluation, but it requires contrast agents and is accompanied by radiation risks. In contrast, ultrasonic vector Doppler imaging has the advantages of simple calculation, low price, non-invasive and non-radiative, etc., and is widely used in the real-time monitoring of clinical blood flow velocity distribution. However, it is very important to further improve the accuracy of the velocity vector (including magnitude and direction) results measured by ultrasonic vector Doppler imaging technology. Summary of the Invention

[0003] The purpose of the present application is to provide an ultrasonic vector Doppler imaging method, device, equipment, medium and product, which can further improve the accuracy of the velocity vector results measured by ultrasonic vector Doppler imaging technology.

[0004] To achieve the above purpose, the present application provides the following solutions:

[0005] In a first aspect, the present application provides an ultrasonic vector Doppler imaging method, including:

[0006] Real-time emitting plane waves to the target area of the object to be detected at different emission angles respectively to obtain the overall echo signals corresponding to each emission angle; there are moving targets inside the target area of the object to be detected, and the overall echo signals include the echo signals at all positions within the target area of the object to be detected at all sampling times;

[0007] For any one emission angle, using a gated time window to intercept the overall echo signal corresponding to the emission angle, retaining the echo signals within the target time period to obtain the radio frequency signal corresponding to the emission angle; the target time period is the time period during which the plane wave corresponding to the emission angle propagates within the moving target in the target area of the object to be detected;

[0008] Coherently combining the radio frequency signals corresponding to each emission angle to obtain a coherently combined radio frequency signal;

[0009] Obtaining in-phase quadrature signals and the average value of the center frequencies of the coherently combined radio frequency signals according to the coherently combined radio frequency signal;

[0010] According to the average value of the center frequencies of the coherently combined RF signals and the first phase shift of the Doppler signals corresponding to the respective positions of the moving target obtained by estimating the in-phase quadrature signals using the autocorrelation method, the axial velocity at each position of the moving target is obtained.

[0011] According to the average value of the center frequencies of the coherently combined RF signals, the second phase shift of the Doppler signals corresponding to the respective positions of the moving target obtained by estimating the first beam signal and the second beam signal using the autocorrelation method, and the third phase shift of the Doppler signals corresponding to the respective positions of the moving target, the axial velocity at the first preset angle at each position of the moving target and the axial velocity at the second preset angle at each position of the moving target are obtained; the first sparse matrix and the second sparse matrix are obtained by delay summation with the first preset angle and the second preset angle as the receiving angles; the first beam signal and the second beam signal are obtained by multiplying the in-phase quadrature signals with the first sparse matrix and the second sparse matrix respectively.

[0012] The improved vector Doppler algorithm is used to process the axial velocity at the first preset angle at each position of the moving target and the axial velocity at the second preset angle at each position of the moving target to obtain a velocity vector; the improved vector Doppler algorithm aims to minimize a cost function, and the cost function is constructed based on the least squares principle with the differences between the axial velocity at the first preset angle at each position of the moving target and the estimated value of the axial velocity at the first preset angle at each position of the moving target, and the differences between the axial velocity at the second preset angle at each position of the moving target and the estimated value of the axial velocity at the second preset angle at each position of the moving target as the errors.

[0013] A color + B-mode ultrasound image and a vector + B-mode ultrasound image are generated according to the in-phase quadrature signals, the axial velocity at each position of the moving target, and the velocity vector.

[0014] In a second aspect, the present application provides an ultrasonic vector Doppler imaging device, including:

[0015] An echo signal acquisition module, configured to transmit plane waves to a target area of an object to be detected at different transmit angles in real time, and obtain overall echo signals corresponding to the respective transmit angles; there is a moving target inside the target area of the object to be detected, and the overall echo signals include echo signals at all positions within the target area of the object to be detected at all sampling moments.

[0016] The gated time window processing module is used to intercept the overall echo signal corresponding to any emission angle using a gated time window, retain the echo signal within the target time period, and obtain the radio frequency signal corresponding to the emission angle; the target time period is the time period during which the plane wave corresponding to the emission angle propagates within the moving target in the target area of the object to be detected.

[0017] The coherent combination module is used to coherently combine the radio frequency signals corresponding to each emission angle to obtain a coherently combined radio frequency signal.

[0018] The radio frequency signal processing module is used to obtain the in-phase quadrature signal and the average value of the center frequencies of the coherently combined radio frequency signals based on the coherently combined radio frequency signal.

[0019] The axial velocity determination module is used to obtain the axial velocity at each position of the moving target based on the average value of the center frequencies of the coherently combined radio frequency signals and the first phase shift of the Doppler signals corresponding to each position of the moving target estimated by using the autocorrelation method for the in-phase quadrature signal.

[0020] The preset angle axial velocity determination module is used to obtain the axial velocity at each position of the moving target at the first preset angle and the axial velocity at each position of the moving target at the second preset angle based on the average value of the center frequencies of the coherently combined radio frequency signals and the second phase shift and the third phase shift of the Doppler signals corresponding to each position of the moving target estimated by using the autocorrelation method for the first beam signal and the second beam signal; the first sparse matrix and the second sparse matrix are obtained by delay summation with the first preset angle and the second preset angle as the receiving angles; the first beam signal and the second beam signal are obtained by multiplying the first sparse matrix and the second sparse matrix with the in-phase quadrature signal respectively.

[0021] The velocity vector determination module is used to process the axial velocity at each position of the moving target at the first preset angle and the axial velocity at each position of the moving target at the second preset angle by using an improved vector Doppler algorithm to obtain a velocity vector; the improved vector Doppler algorithm aims to minimize a cost function, and the cost function is constructed based on the least squares principle with the difference between the axial velocity at each position of the moving target at the first preset angle and the estimated value of the axial velocity at each position of the moving target at the first preset angle and the difference between the axial velocity at each position of the moving target at the second preset angle and the estimated value of the axial velocity at each position of the moving target at the second preset angle as errors.

[0022] The imaging module is used to generate a color + B-mode ultrasound image and a vector + B-mode ultrasound image based on the in-phase quadrature signal, the axial velocity at each position of the moving target, and the velocity vector.

[0023] In a third aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the computer program to implement the ultrasonic vector Doppler imaging method described in any one of the above.

[0024] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the ultrasonic vector Doppler imaging method described in any one of the above.

[0025] In a fifth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the ultrasonic vector Doppler imaging method described in any one of the above.

[0026] According to the specific embodiments provided by the present application, the present application has the following technical effects:

[0027] The present application provides an ultrasonic vector Doppler imaging method, device, equipment, medium, and product. It uses a gated time window to intercept the overall echo signal corresponding to the transmission angle, selectively processes the target signal, reduces the influence of clutter, and improves the signal-to-noise ratio. It uses the average value of the center frequencies of the radio frequency signals after coherent compounding instead of the center frequency of the transmission signal to calculate the target axial velocity, reducing the error caused by the change in the signal spectrum, thereby improving the accuracy of velocity estimation. A cost function is constructed according to the least squares method, and the least squares method can minimize the error between the axial velocity and the axial velocity, thereby obtaining the optimal velocity estimation. It uses multi-angle information to improve the accuracy and robustness of velocity estimation to further reduce the error generated by velocity estimation. Therefore, the present application can further improve the accuracy of the velocity vector result measured by the ultrasonic vector Doppler imaging technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is a flowchart of the ultrasonic vector Doppler imaging method provided by an embodiment of the present application;

[0030] Figure 2 It is a schematic diagram of the transmission time of the gated time window in a non-deflected plane wave (zero degree) in the present application;

[0031] Figure 3Schematic diagram of the gating time window for the transmission time of the deflected plane wave (deflection angle α) in this application;

[0032] Figure 4 Schematic diagram of coherent compounding in this application;

[0033] Figure 5 Schematic diagram of the rotating disk model used in an embodiment of this application;

[0034] Figure 6 is Figure 5 corresponding rotating disk B-mode ultrasound image;

[0035] Figure 7 is Figure 5 corresponding rotating disk color Doppler image;

[0036] Figure 8 is Figure 5 corresponding rotating disk vector Doppler image;

[0037] Figure 9 is Figure 5 corresponding rotating disk B-mode ultrasound + color Doppler image;

[0038] Figure 10 is Figure 5 corresponding rotating disk B-mode ultrasound + vector Doppler image;

[0039] Figure 11 Schematic diagram of the structure of a computer device provided by an embodiment of this application. Detailed implementation manners

[0040] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0041] To make the above objects, features, and advantages of this application more obvious and understandable, the following further detailed description of this application will be given in conjunction with the accompanying drawings and specific implementation manners.

[0042] The principle of vector Doppler is as follows: In ultrasonic imaging, the transmitted ultrasonic waves are scattered by moving targets, resulting in a change in the frequency of the received ultrasonic waves, i.e., the Doppler frequency shift. Vector Doppler uses Doppler frequency shift measurements at multiple different angles to calculate the complete velocity vector of the flow. The specific steps are as follows: It is achieved by placing multiple ultrasonic transducers at different angles, or by controlling a single transducer to transmit and receive ultrasonic waves at different angles. First, the ultrasonic probe emits high-frequency ultrasonic signals. When the ultrasonic signals encounter moving targets, a part of the signals will be reflected back by the moving targets to form echo signals. The echo signals are subjected to wall filtering processing to extract the moving target signals and remove the interference signals from the surrounding tissues. Then, the Doppler frequency shifts at different angles are obtained through the autocorrelation method, and the axial velocities at different angles are calculated based on the central frequency of the transmitted signal and the Doppler frequency shift (Axial velocity: In medical ultrasound and Doppler imaging, the axial velocity is usually used to describe the velocity of blood flow or tissue movement, especially the velocity component parallel to the direction of ultrasonic wave propagation). Finally, the longitudinal and transverse components of the velocity are calculated based on the axial velocities at different angles, thereby obtaining the complete vector of the velocity. Since the echo signals contain both acoustic information from moving targets and signals from the surrounding tissues, and wall filtering cannot completely remove the clutter interference from the surrounding tissues. Moreover, after the transmitted ultrasonic waves propagate through tissues, their spectra will be affected by moving targets, so the frequency of the received signals is not exactly the same as the frequency of the transmitted signals. Finally, due to the lack of optimization in the traditional vector Doppler algorithm, there are large errors in calculating the vector velocity.

[0043] Based on this, as Figure 1 shown, the present application provides an ultrasonic vector Doppler imaging method, including the following steps, where:

[0044] Plane waves are respectively emitted to the target area of the object to be detected at different emission turning angles in real time to obtain the overall echo signals corresponding to each emission turning angle; there are moving targets inside the target area of the object to be detected, and the overall echo signals include the echo signals at all positions within the target area of the object to be detected at all sampling times, which is a three-dimensional data.

[0045] For any one emission turning angle, a gated time window is used to intercept the overall echo signal corresponding to the emission turning angle, and the echo signal within the target time period is retained to obtain the radio frequency signal corresponding to the emission turning angle; the target time period is the time period during which the plane wave corresponding to the emission turning angle propagates within the moving targets in the target area of the object to be detected.

[0046] The radio frequency signals corresponding to each emission turning angle are coherently combined to obtain the coherently combined radio frequency signal.

[0047] The in-phase quadrature signal and the average value of the central frequency of the coherently combined radio frequency signal are obtained based on the coherently combined radio frequency signal.

[0048] Based on the average value of the center frequency of the coherently combined RF signal and the first phase shift of the Doppler signals corresponding to each position of the moving target obtained by estimating the in-phase quadrature signals using the autocorrelation method, the axial velocity at each position of the moving target is obtained.

[0049] Based on the average value of the center frequency of the coherently combined RF signal, the second phase shift of the Doppler signals corresponding to each position of the moving target obtained by estimating the first beam signal and the second beam signal using the autocorrelation method, and the third phase shift of the Doppler signals corresponding to each position of the moving target, the axial velocity at each position of the moving target at the first preset angle and the axial velocity at each position of the moving target at the second preset angle are obtained; the first sparse matrix and the second sparse matrix are obtained by delay summation with the first preset angle and the second preset angle as the receiving angles; the first beam signal and the second beam signal are obtained by multiplying the in-phase quadrature signal with the first sparse matrix and the second sparse matrix respectively.

[0050] The improved vector Doppler algorithm is used to process the axial velocity at each position of the moving target at the first preset angle and the axial velocity at each position of the moving target at the second preset angle to obtain a velocity vector; the improved vector Doppler algorithm aims to minimize the cost function, and the cost function is constructed according to the least squares principle with the difference between the axial velocity at each position of the moving target at the first preset angle and the estimated value of the axial velocity at each position of the moving target at the first preset angle and the difference between the axial velocity at each position of the moving target at the second preset angle and the estimated value of the axial velocity at each position of the moving target at the second preset angle as the errors.

[0051] A color + B-mode ultrasound image and a vector + B-mode ultrasound image are generated based on the in-phase quadrature signal, the axial velocity at each position of the moving target, and the velocity vector.

[0052] In an exemplary embodiment, plane waves are respectively transmitted to the target region of the object to be detected at different real-time transmission turning angles (α 1 , α 2 and α 3 ) to obtain the overall echo signals corresponding to each transmission turning angle, and the gated time window is used to intercept the overall echo signals corresponding to the transmission turning angle, and the echo signals within the target time period are retained to obtain the RF signals (RF 1 , RF 2 and RF 3 ) corresponding to the transmission turning angle, specifically:

[0053] 1. Transmitting plane waves: Using an ultrasonic transducer to transmit plane waves, successively at three different turning angles (α 1 , α 2 , α3 ) Ultrasonic waves are emitted, and these angles are used to cover the target area within a certain range to obtain the scattering information of the target (the target area of the object to be detected) from different directions.

[0054] 2. Receive the scattered signals: The plane waves will generate scattering after encountering tissues or scatterers, and these scattered signals are received by the array elements of the ultrasonic transducer. The plane waves emitted at different angles will obtain different echo signals, reflecting the characteristics of the scatterer from various angles.

[0055] 3. In order to selectively analyze the signals at a specific depth, a gated time window w(t) is used to apodize the received RF signals. The gated time window acts on the received signals (i.e., the overall echo signals above), intercepts the echo signals within the target time period, and ensures that only the signals corresponding to the target depth (the depth at which the moving target is located within the target area of the object to be detected) are retained. This processing can effectively filter out the interference from other depths, making the apodized signals more focused on the area of interest.

[0056] The operation of the gated time window is often used to extract the echo signals of specific targets in ultrasonic signals. Specifically:

[0057] The part assigned a value of 1: corresponds to the target time t = t 1 , which means that the signals corresponding to the time when the ultrasonic waves propagate in the moving target are retained.

[0058] The part assigned a value of 0: corresponds to non-target times (i.e., t ≠ t 1 ), which means that the signals corresponding to the time when the ultrasonic waves propagate in non-moving targets or other interference signals are not retained.

[0059] The gated time window w(t) is defined as:

[0060]

[0061] where t is the time when the ultrasonic waves propagate in the tissue, t 1 is the time when the ultrasonic waves propagate in the medium of the moving object in the tissue, and w(t) is the gated time window function.

[0062] Determination of the gated time t 1 : Use the conventional B-mode ultrasound to obtain the two-dimensional grayscale images of the object to be detected and the moving target to determine the area of the moving target. Determine t 1 according to the sound speed and the target depth. The propagation speed of the ultrasonic signals in the object to be detected is known, so the time t 1 of the echo signals can be calculated through the depth of the moving target. Assume that the X direction is parallel to the transducer and the Z direction represents the imaging depth:

[0063] During the emission of a 0° plane wave, the transmission time t of the emitted signal passing through the scatterer (x, z) and then being backscattered to another array element x' 1 can be calculated by the formula , as shown in the schematic diagram Figure 2 , where x represents the relative position between the transmitting array element and the scatterer in the transverse direction, and z represents the relative position between the transmitting array element and the scatterer in the longitudinal direction.

[0064] During the emission of a plane wave with an inclination angle of α, the transmission time t of the emitted signal passing through the scatterer (x, z) and then being backscattered to another array element x' 1 can be calculated by the formula , as shown in the schematic diagram Figure 3 shown.

[0065] 4. Generate RF signals: The RF signals after being processed by the gated time window are the scattering information obtained from different angles, denoted as RF 1 , RF 2 and RF 3 respectively. These signals contain the echo characteristics of the target area at each emission angle and can be used for subsequent image reconstruction or velocity estimation.

[0066] In an exemplary embodiment, the RF signals corresponding to each emission rotation angle are coherently combined to obtain the coherently combined RF signal. Specifically:

[0067] RF 1 , RF 2 and RF 3 are coherently combined, and the coherently combined RF signal compound_RF can be calculated by the formula compound_RF = RF 1 + RF 2 + RF 3 , as shown in the schematic diagram Figure 4 shown.

[0068] In an exemplary embodiment, obtaining the in-phase quadrature signal and the average value of the center frequency of the coherently combined RF signal based on the coherently combined RF signal specifically includes:

[0069] Demodulate the coherently combined RF signal to obtain the in-phase quadrature signal.

[0070] Calculate the average value of the center frequency of the coherently combined RF signal according to the coherently combined RF signal.

[0071] In an exemplary embodiment, demodulate the coherently combined RF signal compoud_RF to obtain the in-phase quadrature signal IQ. Specifically:

[0072] The mixing operation is performed using two orthogonal local oscillator signals (one in phase with the RF signal and the other 90 degrees out of phase with it). The mixing operation multiplies the two orthogonal local oscillator signals with the RF signal respectively to generate the in-phase component I' and the quadrature component Q'. Then, low-pass filtering is performed on the I' and Q' signals respectively to remove the high-frequency components and retain the baseband signals, obtaining the low-pass filtered in-phase component I and the low-pass filtered quadrature component Q. Finally, the in-phase and quadrature signal IQ is obtained based on I and Q, where IQ = I + j*Q and j is the imaginary unit.

[0073] The specific steps are as follows:

[0074] 1. Generate local oscillator signals: Use two local oscillator signals, one in phase with the RF signal cos(ωt) and the other 90 degrees out of phase with the RF signal sin(ωt). These two signals are orthogonal to each other, that is, their inner product is zero. ω is the angular frequency of the RF signal compound_RF.

[0075] 2. Mixing operation: Multiply the RF signal compound_RF with the two local oscillator signals respectively to generate two intermediate frequency signals:

[0076] In-phase signal I' = compound_RF · cos(ωt)

[0077] Quadrature signal Q' = compound_RF · sin(ωt)

[0078] 3. Low-pass filtering: Perform low-pass filtering on I' and Q' respectively to remove the high-frequency components and only retain the baseband part, obtaining the low-pass filtered in-phase component I and the quadrature component Q.

[0079] 4. The signal can be expressed in complex form: IQ = I + j·Q.

[0080] Where I and Q are the low-pass filtered in-phase component and quadrature component respectively, and j is the imaginary unit

[0081] In an exemplary embodiment, the average value of the center frequency of the coherently combined RF signal is calculated based on the coherently combined RF signal, specifically:

[0082] 1. Select a column of data from the three-dimensional signal compound_RF (with size K×H×10L) (the coherently combined RF signals at K spatial positions at a fixed depth h (1 < h < H) at 10L sampling instants). The selected data size is K×10L. Divide the sample into 10 parts, and the size of each sample data is K×L.

[0083] 2. Perform the Fast Fourier Transform (FFT) on the i-th sample data to obtain the frequency-domain FFT_sample i :

[0084]

[0085] where denotes the Fast Fourier Transform (FFT), and FFT_sample i is of size K×L.

[0086] 3. Calculate the average power P of the i-th sample i :

[0087] P i = mean(FFT_sample i 2 , 2) (i = 1, 2, 3, … 10)

[0088] where mean(FFT_sample i 2 , 2) denotes taking the average of FFT_sample i 2 in the second dimension, and P i is of size K×1.

[0089] 4. Normalize the average power of the i-th sample:

[0090]

[0091] where, P i(max) denotes the maximum value in the array P i .

[0092] 5. Smooth the normalized spectrum of the i-th sample:

[0093]

[0094] where denotes smoothing .

[0095] 6. Calculate the center frequency of the i-th sample:

[0096]

[0097] where f represents the frequency variable, i.e., the frequency value within the current integration range.

[0098] 7. Calculate the average of the center frequencies of the 10 samples:

[0099]

[0100] In an exemplary embodiment, obtaining the axial velocity at each position of the moving target based on the average value of the center frequencies of the coherently combined RF signals and the first phase shift of the Doppler signals corresponding to each position of the moving target estimated by using the autocorrelation method for the in-phase quadrature signals specifically includes:

[0101] For any position (i, j) of the moving target, according to the formula calculate the first phase shift of the Doppler signal corresponding to the position (i, j) of the moving target, where represents the first phase shift of the Doppler signal corresponding to the position (i, j) of the moving target, Q(m)(i, j) represents the quadrature component corresponding to the position (i, j) of the moving target at the sampling time m in the in-phase quadrature signal, I(m - 1)(i, j) represents the in-phase component corresponding to the position (i, j) of the moving target at the sampling time m - 1 in the in-phase quadrature signal, I(m)(i, j) represents the in-phase component corresponding to the position (i, j) of the moving target at the sampling time m in the in-phase quadrature signal, Q(m - 1)(i, j) represents the quadrature component corresponding to the position (i, j) of the moving target at the sampling time m - 1 in the in-phase quadrature signal, N represents the total number of sampling times, and arctan represents the arctangent function.

[0102] According to the formula calculate the axial velocity at the position of the moving target, where v(i, j) represents the axial velocity at the position (i, j) of the moving target, c represents the transmission speed of ultrasonic waves in the object to be detected, f C represents the average value of the center frequencies of the coherently combined RF signals, f prf is the pulse repetition frequency.

[0103] In an exemplary embodiment, before obtaining the axial velocity at the first preset angle at each position of the moving target and the axial velocity at the second preset angle at each position of the moving target based on the average value of the center frequencies of the coherently combined RF signals and the second phase shift of the Doppler signals corresponding to each position of the moving target and the third phase shift of the Doppler signals corresponding to each position of the moving target estimated by using the autocorrelation method for the first beam signal and the second beam signal, it further includes:

[0104] Taking the first preset angle and the second preset angle as the reception angles, performing delay summation to obtain a first sparse matrix and a second sparse matrix.

[0105] Multiplying the first sparse matrix and the second sparse matrix with the in-phase quadrature signal respectively to obtain a first beam signal and a second beam signal.

[0106] In an exemplary embodiment, the first preset angle +θ and the second preset angle -θ are used as receiving angles, and delay summation is performed to obtain the first sparse matrix DAS 1 and the second sparse matrix DAS 2 , specifically as follows:

[0107] 1. Delay time calculation: According to the physical principle of signal propagation, for the receiving angles +θ and -θ respectively, calculate the delay time of the signal arriving at each sensor. Specifically, the delay time is determined by the time difference of the ultrasonic wave propagating from the target to each receiving sensor, and the calculation process involves geometric information (the distance between the sensor and the target) and the propagation speed (usually the speed of sound).

[0108] 2. Delay and weighting processing: According to the calculated delay time, perform delay and weighting processing on the received signal to obtain the signal after delay and weighting processing. After obtaining the calculated delay time, the received signal can be delayed. Delay processing means moving the signal forward or backward to align all received signals so that the signals from the same scattering point are synchronized. Weighting processing means applying a certain weight (such as a Hanning window and other weighting functions) to the delayed signal to optimize the signal quality or suppress noise. In this way, for each receiving angle (+θ and -θ), the signal after delay and weighting processing will be obtained.

[0109] 3. Summation operation: Perform a summation operation on the delayed and weighted signals to obtain the sparse matrix DAS 1 and DAS 2 . The delayed and weighted signals are summed to enhance the signals from the same scattering point and reduce noise. In this process, since there are two receiving angles +θ and -θ, two different sparse matrices DAS 1 and DAS 2 will be obtained correspondingly. These two matrices represent the signals received and processed from different angles.

[0110] In an exemplary embodiment, the first sparse matrix DAS 1 and the second sparse matrix DAS 2 are respectively multiplied by the in-phase quadrature signal IQ to obtain the first beam signal and the second beam signal, and the calculation formula is:

[0111] IQ 1 = IQ × DAS 1 = I 1 + jQ 1

[0112] IQ 2 = IQ × DAS 2 = I 2 + jQ 2

[0113] wherein, I 1 and Q 1 are respectively the in-phase component and the quadrature component of the first beam signal IQ 1 ; I 2 and Q 2 are respectively the in-phase component and the quadrature component of the second beam signal IQ 2 , and j is the imaginary unit

[0114] In an exemplary embodiment, according to the average value of the center frequencies of the radio frequency signals after coherent combining and the second phase shift of the Doppler signals corresponding to the respective positions of the moving target obtained by estimating the first beam signal and the second beam signal using the autocorrelation method and the third phase shift of the Doppler signals corresponding to the respective positions of the moving target, the axial velocity of the moving target at the first preset angle at each position of the moving target and the axial velocity of the moving target at the second preset angle at each position of the moving target are obtained, which specifically includes:

[0115] For any position (i, j) of the moving target, according to the formula calculate the second phase shift of the Doppler signal corresponding to the position (i, j) of the moving target, wherein represents the second phase shift of the Doppler signal corresponding to the position (i, j) of the moving target, Q 1 (m)(i, j) represents the quadrature component corresponding to the position (i, j) of the moving target at the sampling time m in the first beam signal, I 1 (m - 1)(i, j) represents the in-phase component corresponding to the position (i, j) of the moving target at the sampling time m - 1 in the first beam signal, I 1 (m)(i, j) represents the in-phase component corresponding to the position (i, j) of the moving target at the sampling time m in the first beam signal, Q 1 (m - 1)(i, j) represents the quadrature component corresponding to the position (i, j) of the moving target at the sampling time m - 1 in the first beam signal, N represents the total number of sampling times, and arctan represents the arctangent function

[0116] According to the formula calculate the third phase shift of the Doppler signal corresponding to the position (i, j) of the moving target, wherein represents the third phase shift of the Doppler signal corresponding to the position (i, j) of the moving target, Q 2 (m)(i, j) represents the quadrature component corresponding to the position (i, j) of the moving target at the sampling time m in the second beam signal, I 2 (m - 1)(i, j) represents the in-phase component corresponding to the position (i, j) of the moving target at the sampling time m - 1 in the second beam signal2 (m)(i, j) represents the in-phase component corresponding to the moving target position (i, j) at the sampling time m in the second beam signal, Q 2 (m - 1)(i, j) represents the quadrature component corresponding to the moving target position (i, j) at the sampling time m - 1 in the second beam signal.

[0117] According to the formula calculate the axial velocity of the moving target position (i, j) at the first preset angle, where, represents the axial velocity of the moving target position (i, j) at the first preset angle, c represents the transmission speed of ultrasonic waves in the object to be detected, f C represents the average value of the center frequency of the radio frequency signal after coherent compounding, f prf is the pulse repetition frequency.

[0118] According to the formula calculate the axial velocity of the moving target position (i, j) at the second preset angle, where, represents the axial velocity of the moving target position (i, j) at the second preset angle.

[0119] In an exemplary embodiment, an improved vector Doppler algorithm is used to process the axial velocity of each position of the moving target at the first preset angle and the axial velocity of each position of the moving target at the second preset angle to obtain a velocity vector, specifically including:

[0120] Obtain a first preset angle matrix according to the first preset angle.

[0121] Obtain a second preset angle matrix according to the second preset angle.

[0122] Obtain a first axial velocity matrix according to the axial velocity of each position of the moving target at the first preset angle.

[0123] Obtain a second axial velocity matrix according to the axial velocity of each position of the moving target at the second preset angle.

[0124] According to the formula calculate the velocity vector, where, V represents the velocity vector, S θ represents the first preset angle matrix, S -θ represents the second preset angle matrix, represents the first axial velocity matrix, represents the second axial velocity matrix, S θ T represents the transpose of S θ for S -θ T represents the transpose of S -θ for S

[0125] If the size of the signal is M×N×T, in an exemplary embodiment, a first preset angle matrix is obtained according to a first preset angle, specifically:

[0126]

[0127] A second preset angle matrix is obtained according to a second preset angle, specifically:

[0128]

[0129] Matrix S θ and matrix S -θ both have a size of M×2M.

[0130] A first axial velocity matrix is obtained according to the axial velocities at the first preset angle at each position of the moving target, specifically:

[0131]

[0132] A second axial velocity matrix is obtained according to the axial velocities at the second preset angle at each position of the moving target, specifically:

[0133]

[0134] Matrix and matrix both have a size of M×N.

[0135] The derivation of the improved vector Doppler algorithm is as follows:

[0136] For a certain determined position point, assume that the velocity vector is known

[0137] From and it can be known that

[0138] Let

[0139] Then

[0140] Then

[0141] If there are M×N position points, then at the position point (i,j), the axial velocity in the direction of the reception angle θ is measured using the autocorrelation method

[0142]

[0143] If there are M×N position points, then at the position point (i,j), using v x (i,j) and v z (i,j), the axial velocity in the direction of the received angle θ is measured

[0144] Let

[0145] Let

[0146] Then

[0147] Similarly

[0148] Construct a cost function according to the least square principle:

[0149] Convert it into an optimization problem:

[0150] Let That is

[0151] Then

[0152] Arrange the above formula:

[0153] Solve and prove:

[0154] The reason why the improved vector Doppler algorithm can achieve the velocity estimation of blood flow or other moving targets is based on the following principles:

[0155] 1. Vector decomposition and reconstruction: Through the velocity information of multiple receiving angles, the moving velocity can be decomposed into components in different directions, and there is a linear relationship between these components and the overall velocity vector of the target.

[0156] 2. Utilization of geometric relationships: By using geometric relationships and angle sparse matrices, the velocity information measured from different angles can be accurately combined to obtain a complete description of the target motion.

[0157] 3. Least square optimization: The least square method can minimize the error between the preset axial velocity of the angle and the estimated value of the axial velocity, so as to obtain the optimal velocity estimation. This method uses multi-angle information to improve the accuracy and robustness of velocity estimation.

[0158] In an exemplary embodiment, a color + B-mode ultrasound image and a vector + B-mode ultrasound image are generated based on in-phase quadrature signals, axial velocities at various positions of a moving target, and velocity vectors. Specifically:

[0159] Calculate the envelope of IQ, and then perform logarithmic compression to obtain a two-dimensional grayscale B-mode ultrasound image.

[0160] According to the axial velocities at various positions of the moving target and a preset color scale, map the calculated axial velocities to colors to obtain a color Doppler image.

[0161] According to the vector velocity V, calculate the magnitude and direction of the blood flow velocity, and use vector graphics such as arrows or streamlines to visually represent the direction and magnitude of the velocity to generate a vector Doppler image.

[0162] Finally, superimpose the generated color Doppler image on the grayscale B-mode ultrasound image to generate a color + B-mode ultrasound image; superimpose the generated vector Doppler image on the grayscale B-mode ultrasound image to generate a vector + B-mode ultrasound image.

[0163] The present application has the following technical effects:

[0164] The main disadvantage of traditional vector Doppler is that wall filtering cannot completely eliminate the interference of the blood vessel wall and surrounding tissues. In addition, the spectrum of the received signal is not exactly the same as that of the transmitted signal, and coupled with the lack of optimization of the algorithm, these factors may ultimately lead to a large error in velocity estimation. The ultrasonic vector Doppler imaging method proposed in the present application uses time gating technology to be able to select target signals from the original radio frequency signals for subsequent processing, selectively process the target signals, reduce the influence of clutter, and improve the signal-to-noise ratio. It is proposed to use the estimated mean of the center frequency of the received signal instead of the center frequency of the transmitted signal to calculate the axial velocity, reduce the error caused by the change of the signal spectrum, and improve the accuracy of axial velocity estimation. Finally, the algorithm of vector Doppler is also improved (construct a cost function according to the least squares method, and the least squares method can minimize the error between the axial velocity at a preset angle and the estimated value of the axial velocity, so as to obtain the optimal velocity estimation. This method uses multi-angle information to improve the accuracy and robustness of velocity estimation) to further reduce the error generated by velocity estimation.

[0165] The present application also provides a specific embodiment, using the method provided in the above embodiment to Figure 5 process the disk model shown in the figure, and introduce the method provided in the above embodiment:

[0166] Step 1:

[0167] Place the disk in a cube with dimensions of 4×4×4 cm 3inside the model (horizontal, axial, height). The height of the disc is H = 2 cm, the radius is R = 1 cm, and the rotational speed is w = 10 revolutions per second. The velocity distribution inside the disc follows v = w·r, where r is the distance from any point inside the disc to the center of the circle, and 0 ≤ r ≤ R. The maximum velocity v max = 2π×10×0.01 = 0.628 m / s.

[0168] It should be noted that the velocity magnitudes and directions at different spatial positions of the rotating disc model are different, and the theoretical value calculation is simple, which is widely used to verify various new algorithms in the field of ultrasonic Doppler.

[0169] Step 2:

[0170] Respectively, scan the disc model with the emission rotation angles of α 1 = -3°, α 2 = 0°, and α 3 = 3° for the plane wave to generate the radio frequency signals RF 1 、RF 2 and RF 3 windowed by the gated time window.

[0171] Step 3:

[0172] Coherently combine the radio frequency signals RF 1 、RF 2 and RF 3 acquired from multiple angles in Step 2 to generate the coherently combined radio frequency signal compoud_RF.

[0173] Step 4:

[0174] Demodulate the radio frequency signal compoud_RF obtained in Step 3 to generate the in-phase quadrature signal IQ.

[0175] Step 5:

[0176] Estimate the center frequency fc of the received signal based on the radio frequency signal conpoud_RF obtained in Step 3. The process is as follows:

[0177] 1. Select the 64th column data of compound_RF(3000×128×60), and the selected data size is 3000×60. Divide the samples into 10 parts, and the size of each sample data is 3000×6.

[0178] 2. Perform fast Fourier transform (FFT) on the i-th sample data to obtain the frequency domain, where the size of FFT_sample i is 3000×6.

[0179] 3. Calculate the average power of the i-th sample, where P iThe size is 3000×1.

[0180] 4. Normalize the average power of the i-th sample.

[0181] 5. Smooth the normalized spectrum of the i-th sample.

[0182] 6. Calculate the center frequency of the i-th sample.

[0183] 7. Calculate the average value of the center frequencies of 10 samples.

[0184] Step Six:

[0185] Calculate the first phase shift of the Doppler signal according to the in-phase and quadrature signal IQ obtained in Step Four

[0186] Step Seven:

[0187] According to the first phase shift of the Doppler signal obtained in Step Six and the center frequency f obtained in Step Five c , obtain the axial velocity from the ultrasonic Doppler formula. In this application, c = 1540 m / s and f prf = 10000 Hz.

[0188] Step Eight:

[0189] Perform delay summation with +15° and -15° as the receiving angles to obtain the sparse matrices DAS 1 and DAS 2 . The principle is as follows:

[0190] 1. With +15° and -15° as the receiving angles, calculate the corresponding delay times according to the physical principle of signal propagation.

[0191] 2. Delay and weight the received signals according to the calculated delay times.

[0192] 3. Sum the delayed and weighted signals to obtain the sparse matrices DAS 1 and DAS 2 .

[0193] Step Nine:

[0194] Calculate the products of the sparse matrices DAS 1 and DAS 2 obtained in Step Eight and the IQ signal obtained in Step Three to obtain the signals IQ 1 and IQ 2 .

[0195] Step Ten:

[0196] According to the signal IQ obtained in Step Nine 1 and IQ 2 , calculate the second phase shift and the third phase shift of the Doppler signal and

[0197] Step Eleven:

[0198] According to what is obtained in Step Ten and the center frequency f obtained in Step Five c , obtain the axial velocity in the direction of ±15° by the ultrasonic Doppler formula, where, in this application, c = 1540 m / s, f prf = 10000 Hz.

[0199] Step Twelve:

[0200] According to the axial velocity in the direction of ±15° obtained in Step Ten, apply the improved vector Doppler algorithm to obtain the velocity vector V.

[0201] Step Thirteen:

[0202] Calculate the envelope of the in-phase and quadrature signal IQ obtained in Step Four, and then perform logarithmic compression to obtain a two-dimensional gray-scale B-mode ultrasound image, the result is as Figure 6 shown.

[0203] According to the axial velocity obtained in Step Seven and the preset color scale, map the calculated velocity to colors to obtain a color Doppler image, the result is as Figure 7 shown.

[0204] According to the vector velocity V obtained in Step Twelve, calculate the magnitude and direction of the velocity, and use vector graphics such as arrows or streamlines to visually represent the direction and magnitude of the velocity, generating a vector Doppler image, the result is as Figure 8 shown.

[0205] Finally, superimpose the generated color Doppler image on the gray-scale B-mode ultrasound image to generate a color + B-mode ultrasound image, the result is as Figure 9 shown; superimpose the generated vector Doppler image on the gray-scale B-mode ultrasound image to generate a vector + B-mode ultrasound image, the result is as Figure 10 shown.

[0206] This application also provides an application scenario, which applies the above ultrasonic vector Doppler imaging method. Specifically: The ultrasonic vector Doppler imaging method provided in this embodiment can be applied to measure the blood flow velocity or measure the omnidirectional velocity vector (longitudinal component and transverse component) of the flowing blood or moving tissue during muscle movement.

[0207] Based on the same inventive concept, an embodiment of the present application further provides an ultrasonic vector Doppler imaging device for implementing the ultrasonic vector Doppler imaging method involved above. The solution provided by this device for solving the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the ultrasonic vector Doppler imaging device provided below can refer to the limitations on the ultrasonic vector Doppler imaging method in the above text and will not be repeated here.

[0208] In an exemplary embodiment, an ultrasonic vector Doppler imaging device is provided, including:

[0209] An echo signal acquisition module, configured to respectively transmit plane waves to the target area of the object to be detected at different transmission angles in real time, and obtain the overall echo signals corresponding to each transmission angle; there are moving targets inside the target area of the object to be detected, and the overall echo signals include the echo signals at all positions within the target area of the object to be detected at all sampling times.

[0210] A gating time window processing module, configured to, for any one transmission angle, intercept the overall echo signal corresponding to the transmission angle using a gating time window, retain the echo signals within the target time period, and obtain the radio frequency signal corresponding to the transmission angle; the target time period is the time period during which the plane wave corresponding to the transmission angle propagates within the moving target in the target area of the object to be detected.

[0211] A coherent compounding module, configured to coherently compound the radio frequency signals corresponding to each transmission angle to obtain a coherently compounded radio frequency signal.

[0212] A radio frequency signal processing module, configured to obtain an in-phase quadrature signal and the average value of the center frequencies of the coherently compounded radio frequency signals based on the coherently compounded radio frequency signal.

[0213] An axial velocity determination module, configured to obtain the axial velocity at each position of the moving target based on the average value of the center frequencies of the coherently compounded radio frequency signals and the first phase shift of the Doppler signals corresponding to each position of the moving target estimated by using the autocorrelation method for the in-phase quadrature signal.

[0214] A preset angle axial velocity determination module is configured to obtain the axial velocity of each position of the moving target at a first preset angle and the axial velocity of each position of the moving target at a second preset angle according to the average value of the center frequencies of the coherently combined RF signals, the second phase shift of the Doppler signals corresponding to each position of the moving target estimated by using the autocorrelation method for the first beam signal and the second beam signal, and the third phase shift of the Doppler signals corresponding to each position of the moving target; the first sparse matrix and the second sparse matrix are obtained by delay summation with the first preset angle and the second preset angle as the receiving angles; the first beam signal and the second beam signal are obtained by multiplying the first sparse matrix and the second sparse matrix with the in-phase quadrature signals respectively.

[0215] A velocity vector determination module is configured to process the axial velocity of each position of the moving target at a first preset angle and the axial velocity of each position of the moving target at a second preset angle by using an improved vector Doppler algorithm to obtain a velocity vector; the improved vector Doppler algorithm aims to minimize a cost function, and the cost function is constructed according to the least squares principle with the difference between the axial velocity of each position of the moving target at the first preset angle and the estimated value of the axial velocity of each position of the moving target at the first preset angle and the difference between the axial velocity of each position of the moving target at the second preset angle and the estimated value of the axial velocity of each position of the moving target at the second preset angle as errors.

[0216] An imaging module is configured to generate a color + B-mode ultrasound image and a vector + B-mode ultrasound image according to the in-phase quadrature signals, the axial velocity of each position of the moving target, and the velocity vector.

[0217] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal, and its internal structure diagram may be as shown in Figure 11 The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store ultrasonic vector Doppler imaging data. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements an ultrasonic vector Doppler imaging method.

[0218] Those skilled in the art can understand that Figure 11 the structure shown in Figure 11 is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the above method embodiments are implemented.

[0219] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the above method embodiments are implemented.

[0220] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the above method embodiments are implemented.

[0221] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with relevant regulations.

[0222] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memories can include read-only memory (ROM), magnetic tapes, floppy disks, flash memories, optical memories, high-density embedded non-volatile memories, resistive random access memories (ReRAM), magnetoresistive random access memories (MRAM), ferroelectric random access memories (FRAM), phase change memories (PCM), graphene memories, etc. Volatile memories can include random access memory (RAM) or external cache memories, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0223] The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logics, data processing logics based on quantum computing, etc., without limitation.

[0224] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0225] Specific examples are used in this article to elaborate on the principles and implementation manners of the present application. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. An ultrasonic vector Doppler imaging method, characterized in that: The ultrasonic vector Doppler imaging method comprises: In real time, plane waves are respectively emitted to the target area of ​​the object to be detected at different emission angles to obtain the overall echo signal corresponding to each emission angle; there is a moving target inside the target area of ​​the object to be detected, and the overall echo signal includes the echo signals of all positions in the target area of ​​the object to be detected at all sampling times; For any transmitting angle, the overall echo signal corresponding to the transmitting angle is intercepted using a gated time window, and the echo signal within a target time period is retained to obtain a radio frequency signal corresponding to the transmitting angle; the target time period is the time period during which the plane wave corresponding to the transmitting angle propagates within a moving target within a target area of ​​the object to be detected; The radio frequency signals corresponding to the transmission angles are coherently combined to obtain a coherently combined radio frequency signal; Obtaining an average value of the center frequency of the in-phase and quadrature signals and the coherently combined radio frequency signal according to the coherently combined radio frequency signal; The axial velocity at each position of the moving target is obtained according to the average value of the center frequency of the radio frequency signal after coherent combination and the first phase shift of the Doppler signal corresponding to each position of the moving target obtained by estimating the in-phase orthogonal signal using the autocorrelation method; According to the average value of the center frequency of the radio frequency signal after coherent compounding and the second phase shift of the Doppler signal corresponding to each position of the moving target and the third phase shift of the Doppler signal corresponding to each position of the moving target obtained by estimating the first beam signal and the second beam signal by the autocorrelation method, the axial velocity of each position of the moving target at the first preset angle and the axial velocity of each position of the moving target at the second preset angle are obtained; the first sparse matrix and the second sparse matrix are obtained by delaying and summing the first preset angle and the second preset angle as the receiving angle; the first beam signal and the second beam signal are obtained by multiplying the in-phase orthogonal signals of the first sparse matrix and the second sparse matrix respectively; An improved vector Doppler algorithm is used to process the axial velocity of each position of the moving target at a first preset angle and the axial velocity of each position of the moving target at a second preset angle to obtain a velocity vector; the improved vector Doppler algorithm takes minimization of a cost function as a goal, and the cost function is constructed according to the least squares principle with the difference between the axial velocity of each position of the moving target at the first preset angle and the estimated value of the axial velocity of each position of the moving target at the first preset angle and the difference between the axial velocity of each position of the moving target at the second preset angle and the estimated value of the axial velocity of each position of the moving target at the second preset angle as errors; Color + B-ultrasound images and vector + B-ultrasound images are generated according to the in-phase orthogonal signals, the axial velocity at each position of the moving target and the velocity vector.

2. The ultrasonic vector Doppler imaging method according to claim 1, characterized in that: The step of obtaining the in-phase orthogonal signal and the average value of the center frequency of the coherently combined radio frequency signal according to the coherently combined radio frequency signal specifically includes: Demodulate the coherently combined RF signal to obtain in-phase and quadrature signals; The average value of the center frequency of the coherently combined radio frequency signal is calculated according to the coherently combined radio frequency signal.

3. The ultrasonic vector Doppler imaging method according to claim 1, characterized in that: The method of obtaining the axial velocity at each position of the moving target based on the average value of the center frequency of the radio frequency signal after coherent combination and the first phase shift of the Doppler signal corresponding to each position of the moving target obtained by estimating the in-phase orthogonal signal using the autocorrelation method specifically includes: For any position (i, j) of a moving target, according to the formula Calculate the first phase shift of the Doppler signal corresponding to the moving target position (i, j), where: represents the first phase shift of the Doppler signal corresponding to the moving target position (i, j), Q(m)(i, j) represents the orthogonal component corresponding to the moving target position (i, j) at sampling time m in the in-phase orthogonal signal, I(m-1)(i, j) represents the in-phase component corresponding to the moving target position (i, j) at sampling time m-1 in the in-phase orthogonal signal, I(m)(i, j) represents the in-phase component corresponding to the moving target position (i, j) at sampling time m in the in-phase orthogonal signal, Q(m-1)(i, j) represents the orthogonal component corresponding to the moving target position (i, j) at sampling time m-1 in the in-phase orthogonal signal, N represents the total number of sampling times, and arctan represents the inverse tangent function; According to the formula Calculate the axial velocity of the moving target at the position, where v(i, j) represents the axial velocity of the moving target at the position (i, j), c represents the transmission velocity of the ultrasonic wave in the object to be detected, and f C Represents the average value of the center frequency of the RF signal after coherent recombination, f prf is the pulse repetition frequency.

4. The ultrasonic vector Doppler imaging method according to claim 1, characterized in that: Before obtaining the axial velocity of each position of the moving target at a first preset angle and the axial velocity of each position of the moving target at a second preset angle according to the average value of the center frequency of the radio frequency signal after coherent combination and the second phase shift of the Doppler signal corresponding to each position of the moving target and the third phase shift of the Doppler signal corresponding to each position of the moving target obtained by estimating the first beam signal and the second beam signal by using the autocorrelation method, the method further includes: Taking the first preset angle and the second preset angle as receiving angles, performing delayed summation to obtain a first sparse matrix and a second sparse matrix; The first sparse matrix and the second sparse matrix are respectively multiplied with the in-phase orthogonal signal to obtain the first beam signal and the second beam signal.

5. The ultrasonic vector Doppler imaging method according to claim 1, characterized in that: According to the average value of the center frequency of the radio frequency signal after coherent combination and the second phase shift of the Doppler signal corresponding to each position of the moving target and the third phase shift of the Doppler signal corresponding to each position of the moving target obtained by estimating the first beam signal and the second beam signal by the autocorrelation method, the axial velocity of each position of the moving target at the first preset angle and the axial velocity of each position of the moving target at the second preset angle are obtained, specifically including: For any position (i, j) of a moving target, according to the formula Calculate the second phase shift of the Doppler signal corresponding to the moving target position (i, j), where represents the second phase shift of the Doppler signal corresponding to the moving target position (i, j), Q1(m)(i, j) represents the orthogonal component corresponding to the moving target position (i, j) at sampling time m in the first beam signal, I1(m-1)(i, j) represents the in-phase component corresponding to the moving target position (i, j) at sampling time m-1 in the first beam signal, I1(m)(i, j) represents the in-phase component corresponding to the moving target position (i, j) at sampling time m in the first beam signal, Q1(m-1)(i, j) represents the orthogonal component corresponding to the moving target position (i, j) at sampling time m-1 in the first beam signal, N represents the total number of sampling times, and arctan represents the inverse tangent function; According to the formula Calculate the third phase shift of the Doppler signal corresponding to the moving target position (i, j), where: represents the third phase shift of the Doppler signal corresponding to the moving target position (i, j), Q2(m)(i, j) represents the orthogonal component corresponding to the moving target position (i, j) at sampling time m in the second beam signal, I2(m-1)(i, j) represents the in-phase component corresponding to the moving target position (i, j) at sampling time m-1 in the second beam signal, I2(m)(i, j) represents the in-phase component corresponding to the moving target position (i, j) at sampling time m in the second beam signal, Q2(m-1)(i, j) represents the orthogonal component corresponding to the moving target position (i, j) at sampling time m-1 in the second beam signal; According to the formula Calculate the axial velocity of the moving target position (i, j) at the first preset angle, where: represents the axial velocity of the moving target position (i, j) at the first preset angle, c represents the transmission velocity of the ultrasonic wave in the object to be detected, and f C Represents the average value of the center frequency of the RF signal after coherent recombination, f prf is the pulse repetition frequency; According to the formula Calculate the axial velocity of the moving target position (i, j) at the second preset angle, where: Indicates the axial velocity of the moving target position (i, j) at the second preset angle.

6. The ultrasonic vector Doppler imaging method according to claim 1, characterized in that: The improved vector Doppler algorithm is used to process the axial velocity of each position of the moving target at the first preset angle and the axial velocity of each position of the moving target at the second preset angle to obtain a velocity vector, specifically including: Obtaining a first preset angle matrix according to the first preset angle; Obtaining a second preset angle matrix according to the second preset angle; Obtaining a first axial velocity matrix according to the axial velocity of each position of the moving target at a first preset angle; Obtaining a second axial velocity matrix according to the axial velocity of each position of the moving target at a second preset angle; According to the formula Calculate the velocity vector, where V represents the velocity vector, S θ represents the first preset angle matrix, S -θ represents the second preset angle matrix, represents the first axial velocity matrix, represents the second axial velocity matrix, S θ T Indicates S θ Find the transpose, S -θ T Indicates S -θ Request transpose.

7. An ultrasonic vector Doppler imaging device, characterized in that: The ultrasonic vector Doppler imaging device comprises: The echo signal acquisition module is used to transmit plane waves to the target area of ​​the object to be detected at different transmission angles in real time to obtain the overall echo signal corresponding to each transmission angle; if there is a moving target inside the target area of ​​the object to be detected, the overall echo signal includes the echo signals of all positions in the target area of ​​the object to be detected at all sampling times; A gated time window processing module is used to intercept the overall echo signal corresponding to any transmitting angle using a gated time window, retain the echo signal within a target time period, and obtain the radio frequency signal corresponding to the transmitting angle; the target time period is the time period during which the plane wave corresponding to the transmitting angle propagates within the moving target within the target area of ​​the object to be detected; A coherent composite module is used to coherently composite the radio frequency signals corresponding to each transmission angle to obtain a coherently composited radio frequency signal; A radio frequency signal processing module, used to obtain the average value of the center frequency of the in-phase orthogonal signal and the radio frequency signal after coherent combination according to the radio frequency signal after coherent combination; An axial velocity determination module is used to obtain the axial velocity at each position of the moving target based on the average value of the center frequency of the radio frequency signal after coherent compounding and the first phase shift of the Doppler signal corresponding to each position of the moving target obtained by estimating the in-phase orthogonal signal using the autocorrelation method; A preset angle axial velocity determination module is used to obtain the axial velocity of each position of the moving target at a first preset angle and the axial velocity of each position of the moving target at a second preset angle according to the average value of the center frequency of the radio frequency signal after coherent compounding and the second phase shift of the Doppler signal corresponding to each position of the moving target obtained by estimating the first beam signal and the second beam signal using the autocorrelation method; the first sparse matrix and the second sparse matrix are obtained by delaying and summing the first preset angle and the second preset angle as the receiving angle; the first beam signal and the second beam signal are obtained by multiplying the first sparse matrix and the second sparse matrix with the in-phase orthogonal signal respectively; A velocity vector determination module, used for processing the axial velocity of each position of the moving target at a first preset angle and the axial velocity of each position of the moving target at a second preset angle using an improved vector Doppler algorithm to obtain a velocity vector; the improved vector Doppler algorithm aims at minimizing a cost function, the cost function is constructed according to the least squares principle with the difference between the axial velocity of each position of the moving target at the first preset angle and the estimated value of the axial velocity of each position of the moving target at the first preset angle and the difference between the axial velocity of each position of the moving target at the second preset angle and the estimated value of the axial velocity of each position of the moving target at the second preset angle as errors; The imaging module is used to generate a color + B-ultrasound image and a vector + B-ultrasound image according to the in-phase orthogonal signals, the axial velocity at each position of the moving target and the velocity vector.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the ultrasonic vector Doppler imaging method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the ultrasonic vector Doppler imaging method according to any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the ultrasonic vector Doppler imaging method according to any one of claims 1 to 6 is implemented.

Images