Ultrasound imaging method based on pearson weighted coefficients of bilateral elements

Abstract

The application relates to an ultrasonic imaging method based on a Pearson weighting coefficient of a bilateral array element, and belongs to the technical field of ultrasonic imaging. The method comprises the following steps: S1, preprocessing echo signals received by ultrasonic array elements to obtain processed ultrasonic echo data; S2, selecting echo data of two array elements at the left and right ends of an array, and calculating a Pearson weighting coefficient by using data of a front and back sampling moment; S3, selecting two array elements at the center of the array, calculating echo mean values of the two array elements, and calculating Pearson weighting coefficients of the echo data of the two array elements at the left and right ends by using data of a front and back sampling moment; S4, calculating a weighted average value with a weight according to the obtained Pearson weighting coefficients to obtain a final Pearson weighting coefficient at a current sampling moment; S5, weighting output of a delay and stack beamformer formed by echoes to sequentially obtain single-frame imaging subgraphs; and S6, spatially compositing multiple imaging subgraphs to obtain high-quality ultrasonic imaging results.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ultrasonic imaging, and relates to an ultrasonic imaging method based on a Pearson weighting coefficient of a double-sided array element. BACKGROUND

[0002] The most widely used and simplest beamforming technology in ultrasonic imaging is delay and sum (DAS), which calculates the delay amount of the received echo signal according to the geometric position relationship of the array element channel, and then aligns and superimposes the delayed data. The traditional DAS algorithm has low complexity and high imaging speed, but the main lobe width increases due to the use of a fixed window function, resulting in low resolution.

[0003] In recent years, in order to improve the contrast and resolution of the beamforming algorithm, adaptive algorithms have been studied more and more. The minimum variance (MV) algorithm has certain improvement on the resolution, but has high algorithm complexity and poor robustness, and cannot be applied to practical situations. The traditional coherence factor (CF) algorithm can improve the contrast of the imaging image to a certain extent, but since it only uses the echo data at the current sampling time, the improvement of the imaging result is relatively limited, and the accuracy of the measurement of the ultrasonic echo coherence needs to be improved, so it is difficult to further improve the overall imaging quality of the image.

[0004] In summary, there is an urgent need for a high-quality beamforming algorithm that can improve the resolution and contrast of the ultrasonic image, greatly reduce the algorithm complexity, and accurately use the ultrasonic echo coherence information, so as to improve the overall imaging quality of the ultrasonic algorithm. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an ultrasonic imaging method based on a Pearson weighting coefficient of a double-sided array element, which overcomes the problem that the traditional coherence coefficient algorithm is based on echo data at a single sampling time and cannot accurately measure the coherence of the algorithm. The method uses an adaptive beamforming algorithm (PCC) based on a Pearson weighting coefficient of a double-sided array element, which has low algorithm complexity, high imaging speed, and an adaptive beamforming method with obvious advantages in contrast improvement, thereby effectively improving the overall effect of the ultrasonic imaging algorithm.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] An ultrasonic imaging method based on a Pearson weighting coefficient of a double-sided array element, specifically comprising the following steps:

[0008] S1: Based on the principle of synthetic aperture imaging, the echo signal received by the ultrasonic array element is preprocessed to obtain the processed ultrasonic echo data.

[0009] S2: Select the echo data from two array elements at the left and right ends of the array, and calculate the Pearson weighting coefficient using data from the preceding and following sampling times. ;

[0010] S3: Select the two center elements of the array and calculate their echo mean. Using data from the sampling time intervals before and after the center elements, calculate the Pearson weighting coefficient between the Pearson coefficient and the echo data from the left and right end elements. This coefficient is denoted as S3. and ;

[0011] S4: Calculate the weighted average value with weights based on the obtained Pearson weighting coefficients, and then calculate the final composite Pearson weighting coefficients of the ultrasonic echo at the current sampling time.

[0012] S5: Weight the output of the delayed superimposed beamformer formed by the echo to obtain the single-frame imaging sub-image in the single-transmit all-receive mode.

[0013] S6: Spatial composite of multiple imaging sub-images from single-shot full-reception mode to obtain ultrasound imaging results.

[0014] Furthermore, in step S1, the echo signal received by the ultrasonic array element is preprocessed, specifically including: time gain compensation (TGC) amplification, AD conversion, and noise filtering, and the data obtained from each transceiver aperture is stored in a data table. A middle, A It is a dimension A three-dimensional numerical table, in which, D Indicates the number of echo sampling points. N Indicates the number of emission apertures. M Indicates the number of receiving apertures; decomposes the detection area into Each pixel is calculated sequentially, and the focusing delay of each detection point within the detection area corresponding to each transceiver aperture is calculated as follows:

[0015]

[0016] in, Indicates the sampling frequency. This indicates the time interval from the start of ultrasonic wave transmission to the first received echo. This indicates the speed at which ultrasonic waves propagate in the medium of the detection area. q This indicates the vertical index of the pixels within the detection area. h This indicates the horizontal index of the pixels within the detection area. n Indicates the aperture number.m Indicates the receiver aperture number; , , , , , Representing points respectively The horizontal and vertical coordinates; Indicates when the detected pixel And the emission aperture is n At that time, receiving aperture m The amount of delay required at the current sampling moment.

[0017] Furthermore, step S2 specifically includes the following steps:

[0018] S21: In the synthetic aperture mode, at the... n During the second launch, the first element and the second... M The echo data received by each receiving element is denoted as and Then the array elements at the left and right ends of the array are at the pixel point The received echo data can be represented as and :

[0019]

[0020] in, Indicates the first n In the second transmission, the first receiving element has a delay period of [number] cycles. Echo data received at the location; and The data length is 2 K +1, which is the number of sampling cycles required to transmit an ultrasonic wave;

[0021] S22: Based on the array elements at the left and right ends of the array at the pixel points Received echo data and Calculate the Pearson weighting coefficients of the ultrasound echo. for:

[0022]

[0023] in, Indicates calculation and covariance of the data and They represent calculations respectively. and The standard deviation of each data point.

[0024] Furthermore, step S3 specifically includes the following steps:

[0025] S31: First, we need to obtain the mean value of the echoes from the two central array elements, denoted as... , is represented as:

[0026]

[0027] in, Indicates the first n The second launch, the first The number of receiving array elements is [number] delay periods. The echo data received at the location, The data length is 2 K +1, which is the number of sampling cycles required to transmit an ultrasonic wave;

[0028] S32: Calculate separately and and At the current pixel Pearson weighted coefficients of ultrasound echo and , is represented as:

[0029] ,

[0030] in, This indicates the calculation of covariance. This represents the standard deviation of the calculated data.

[0031] Further, in step S4, the final composite Pearson weighted coefficient of the ultrasonic echo at the current sampling time is calculated, and the expression is:

[0032]

[0033] in, Indicates the synthetic aperture number n During the next transmission, the beamformer at the pixel point The final ultrasonic echo composite Pearson weighted coefficients were obtained.

[0034] Furthermore, in step S5, a single-frame imaging sub-image in single-transmission all-reception mode is obtained, expressed as:

[0035]

[0036] in, Indicates the first n With multiple emission apertures, the adaptive beamformer based on the Pearson weighting coefficient of the dual-element array achieves pixel-level accuracy in the detection region. The output value, This indicates the pixel number of the original beamformer DAS in the detection area. The output value.

[0037] Furthermore, in step S6, the ultrasound imaging result is obtained, expressed as:

[0038]

[0039] in, This indicates that in synthetic aperture mode, the adaptive beamformer based on Pearson weighting coefficients of the two-sided array elements achieves high performance at the pixel level. The final output value; This indicates a summation operation.

[0040] The beneficial effects of this invention are as follows: compared with existing time-delay superposition ultrasound imaging algorithms, this invention can effectively improve image contrast and has lower algorithm complexity. Compared with traditional coherence coefficient algorithms, this invention can more effectively and accurately measure the coherence of echo signals, thereby further improving the contrast performance of ultrasound imaging images.

[0041] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0043] Figure 1 This is a flowchart illustrating the implementation of the adaptive beamformer PCC based on Pearson weighting coefficients of the two-sided array elements of the present invention.

[0044] Figure 2 The image shows a comparison of the single-column point target imaging results of the three algorithms. Figure 2 (a) is the imaging result of a single-column point target using the Delayed Overlay Algorithm (DAS); Figure 2 (b) is the single-column point target imaging result of the traditional coherence coefficient algorithm (CF); Figure 2 (c) is the single-column point target imaging result of the Pearson weighted adaptive beamformer PCC based on the two-sided array elements of the present invention;

[0045] Figure 3 The graph shows the lateral resolution curves of single-column point target imaging images at a depth of 45mm for three algorithms.

[0046] Figure 4 The graph shows the lateral resolution curves of single-column point target imaging images at a depth of 55 mm for three algorithms.

[0047] Figure 5 The graph shows the lateral resolution curves of point targets at a depth of 65 mm for single-column point target imaging images using three algorithms. Detailed Implementation

[0048] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0049] Please see Figures 1-5 , Figure 1 This is a flowchart illustrating the implementation of the adaptive beamformer PCC based on Pearson weighting coefficients of the two-sided array elements according to the present invention. Figure 1 As shown, this invention designs a Pearson weighted coefficient ultrasound imaging method with two-sided array elements, specifically including the following steps:

[0050] Step S1: Process the echo signal received by the ultrasonic array element, including: time gain compensation (TGC) amplification, AD conversion and noise filtering, and store the data obtained from each transceiver aperture into a data table. A middle, A It is a dimension A three-dimensional numerical table, in which, D Indicates the number of echo sampling points. N Indicates the number of emission apertures. M Indicates the number of receiving apertures; decomposes the detection area into Each pixel is calculated sequentially, and the focusing delay of each detection point within the detection area corresponding to each transceiver aperture is calculated as follows:

[0051]

[0052] in, Indicates the sampling frequency. This indicates the time interval from the start of ultrasonic wave transmission to the first received echo. This indicates the speed at which ultrasonic waves propagate in the medium of the detection area. q This indicates the vertical index of the pixels within the detection area.h This indicates the horizontal index of the pixels within the detection area. n Indicates the aperture number. m Indicates the receiver aperture number; , , , , , Representing points respectively The horizontal and vertical coordinates; Indicates when the detected pixel And the emission aperture is n At that time, receiving aperture m The amount of delay required at the current sampling moment.

[0053] Step S2: Select the echo data of two array elements at the left and right ends of the array, and calculate the Pearson weighting coefficient using the data from the sampling time intervals before and after the sampling time intervals. The specific calculation steps are as follows:

[0054] S21: In the synthetic aperture mode, at the... n During the second launch, the first element and the second... M The echo data received by each receiving element is denoted as and Then the array elements at the left and right ends of the array are at the pixel point The received data is used to calculate the Pearson coefficient. The data can be represented as and :

[0055]

[0056] in, Indicates the first n In the second transmission, the first receiving element has a delay period of [number] cycles. Echo data received at the location; and The data length is 2 K +1 represents the number of sampling cycles required to emit an ultrasonic wave.

[0057] S22: Based on the echo data of the left and right array elements at the pixel level The calculated ultrasonic echo Pearson coefficient for:

[0058]

[0059] in, Indicates calculation and covariance of the data and They represent calculations respectively. and The standard deviation of each data point.

[0060] Step S3: Select the two array elements at the very center of the array, calculate their echo mean, and use the data from the sampling time intervals before and after to calculate their respective Pearson weighting coefficients along with the echo data from the left and right end array elements. and The specific calculation steps are as follows:

[0061] S31: First, we need to obtain the mean value of the echoes from the two central array elements, denoted as... , is represented as:

[0062]

[0063] in, Indicates the first n The second launch, the first The number of receiving array elements is [number] delay periods. The echo data received at the location, The data length is 2 K +1 represents the number of sampling cycles required to emit an ultrasonic wave.

[0064] S32: Calculate separately and and At the current pixel The Pearson coefficient of ultrasonic echo and As shown below:

[0065] ,

[0066] in, This indicates the calculation of covariance. This represents the standard deviation of the calculated data.

[0067] Step S4: Calculate the weighted average value based on the obtained Pearson coefficients to obtain the final weight at the current sampling time. The specific calculation method is as follows:

[0068]

[0069] in, Indicates the synthetic aperture number n During the next transmission, the beamformer at the pixel point The final ultrasonic echo composite Pearson weighted coefficients were obtained.

[0070] Step S5: Weight the output of the delayed superimposed beamformer formed by the echoes to obtain the single-frame imaging sub-images in single-transmit all-receive mode:

[0071]

[0072] in, Indicates the first n With multiple emission apertures, the adaptive beamformer based on the Pearson weighting coefficient of the dual-element array achieves pixel-level accuracy in the detection region. The output value, This indicates the pixel number of the original beamformer DAS in the detection area. The output value.

[0073] Step S6: Spatial composite of the imaging sub-images in single-lens full-reception mode to obtain the final ultrasound imaging result. The specific calculation method is as follows:

[0074]

[0075] in, This indicates that in synthetic aperture mode, the adaptive beamformer based on Pearson weighting coefficients of the two-sided array elements achieves high performance at the pixel level. The final output value; Indicates the first n With multiple emission apertures, the adaptive beamformer based on the Pearson weighting coefficient of the dual-element array achieves pixel-level accuracy in the detection region. The output value, This indicates a summation operation.

[0076] Comparative verification experiment:

[0077] Field II is an ultrasonic experimental simulation platform developed by the Technical University of Denmark based on acoustic principles, and it has gained widespread recognition and use in theoretical research. To verify the effectiveness of the algorithm in this invention, Field II was used to image point scattering targets commonly used in ultrasonic imaging, and imaging comparison experiments were conducted using actual experimental data.

[0078] In the point target imaging simulation experiment, ten strongly scattering point targets were set up with a lateral position at the center 0mm and a longitudinal depth ranging from 45mm to 67.5mm, with an longitudinal spacing of 2.5mm between adjacent target points. This was used to observe the lateral resolution of each algorithm. A synthetic aperture focusing method was used, and the imaging dynamic range was set to 60dB. The data simulation experiment used an array element center frequency of 7MHz, 64 elements, an element spacing of 0.2mm, a sampling frequency of 100MHz, and a sound velocity of 1540m / s. Simultaneously, 20dB of Gaussian white noise was added during the imaging process to test the robustness of each algorithm.

[0079] For the three experimental targets mentioned above, a time-delay superposition algorithm (DAS), a coherence coefficient algorithm (CF), and the adaptive beamforming algorithm (PCC) based on Pearson weighting coefficients of the present invention were used to conduct comparative imaging experiments. Figure 2 Comparison images of point target imaging results from three algorithms are provided. Figure 2 (a) is the imaging result of a single-column point target using the Delayed Overlay Algorithm (DAS); Figure 2 (b) is the single-column point target imaging result of the traditional coherence coefficient algorithm (CF); Figure 2 (c) shows the single-column point target imaging results of the PCC adaptive beamforming algorithm based on Pearson weighting coefficients of bilateral array elements. Figure 2 As can be seen, the DAS algorithm has the worst image quality and the lowest resolution, exhibiting the most lateral artifacts compared to the other two algorithms. The CF algorithm reduces sidelobe artifacts compared to the DAS algorithm, and while its resolution is slightly improved, the improvement is not significant. The PCC algorithm balances resolution contrast with overall algorithmic improvement, showing a significant improvement in lateral resolution for point targets and demonstrating the best effect in removing Gaussian white noise. To more clearly compare the lateral resolution performance of each algorithm at different depths... Figure 3 , Figure 4 , Figure 5 Lateral resolution curves for different algorithms at 45mm, 55mm, and 65mm are presented. It can be seen that, compared to the DAS and CF algorithms, the PCC algorithm proposed in this invention has significant advantages in both lateral main lobe width constraint and side lobe rank suppression.

[0080] Table 1. Comparison of FWHM (Further Working Mass) of the three algorithms at different depths in point target simulation (-6dB).

[0081]

[0082] Table 1 presents a comparison of the main lobe width (FWHM) at different depths in the point target experiment, with an amplitude of -6 dB. Calculations show that the proposed adaptive beamforming algorithm PCC based on bilateral array elements and Pearson weighted coefficients exhibits a significantly reduced main lobe width (FWHM), indicating a substantial narrowing of the main lobe width. This translates to a significant improvement in resolution compared to traditional DAS and CF algorithms. For example, at a depth of 55 mm, PCC's FWHM is superior to the traditional DAS algorithm, effectively reducing the value by 48.81%. Compared to the traditional CF algorithm, the proposed PCC algorithm effectively reduces the FWHM by 41.13%. Therefore, the proposed PCC algorithm demonstrates a significant improvement in resolution compared to traditional algorithms. Overall, PCC is significantly superior to traditional beamforming methods.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An ultrasound imaging method based on Pearson weighted coefficients of a two-sided array element, characterized in that, The method includes the following steps: S1: Based on the principle of synthetic aperture imaging, the echo signal received by the ultrasonic array element is preprocessed to obtain the processed ultrasonic echo data. S2: Select the echo data from two array elements at the left and right ends of the array, and calculate the Pearson weighting coefficient using data from the preceding and following sampling times. ; S3: Select the two center elements of the array and calculate their echo mean. Using data from the sampling time intervals before and after the center elements, calculate the Pearson weighting coefficient between the Pearson coefficient and the echo data from the left and right end elements. This coefficient is denoted as S3. and ; S4: Calculate the weighted average value with weights based on the obtained Pearson weighting coefficients, and then calculate the final composite Pearson weighting coefficients of the ultrasonic echo at the current sampling time. S5: Weight the output of the delayed superimposed beamformer formed by the echo to obtain the single-frame imaging sub-image in the single-transmit all-receive mode. S6: Spatial composite of multiple imaging sub-images from single-shot full-reception mode to obtain ultrasound imaging results; In step S1, the echo signal received by the ultrasonic array element is preprocessed, specifically including: time gain compensation amplification, AD conversion and noise filtering, and the data obtained from each transceiver aperture is stored in a data table. A middle, A It is a dimension A three-dimensional numerical table, in which, D Indicates the number of echo sampling points. N Indicates the number of emission apertures. M Indicates the number of receiving apertures; decomposes the detection area into Each pixel is calculated sequentially, and the focusing delay of each detection point within the detection area corresponding to each transceiver aperture is calculated as follows: in, Indicates the sampling frequency. This indicates the time interval from the start of ultrasonic wave transmission to the first received echo. This indicates the speed at which ultrasonic waves propagate in the medium of the detection area. q This indicates the vertical index of the pixels within the detection area. h This indicates the horizontal index of the pixels within the detection area. n Indicates the aperture number. m Indicates the receiver aperture number; , , , , , Representing points respectively The horizontal and vertical coordinates; Indicates when the detected pixel And the emission aperture is n At that time, receiving aperture m The amount of delay required at the current sampling moment; Step S2 specifically includes the following steps: S21: In the synthetic aperture mode, at the... n During the second launch, the first element and the second... M The echo data received by each receiving element is denoted as and Then the array elements at the left and right ends of the array are at the pixel point The received echo data is represented as and : in, Indicates the first n In the second transmission, the first receiving element has a delay period of [number] cycles. Echo data received at the location; and The data length is 2 K +1, which is the number of sampling cycles required to transmit an ultrasonic wave; S22: Based on the array elements at the left and right ends of the array at the pixel points Received echo data and Calculate the Pearson weighting coefficients of the ultrasound echo. for: in, Indicates calculation and covariance of the data and They represent calculations respectively. and The standard deviations of the data; Step S3 specifically includes the following steps: S31: First, we need to obtain the mean value of the echoes from the two central array elements, denoted as... , is represented as: in, Indicates the first n The second launch, the first The number of receiving array elements is [number] delay periods. The echo data received at the location, The data length is 2 K +1, which is the number of sampling cycles required to transmit an ultrasonic wave; S32: Calculate separately and and At the current pixel Pearson weighted coefficients of ultrasound echo and , is represented as: ， in, This indicates the calculation of covariance. This represents the standard deviation of the calculated data; In step S4, the final Pearson weighted average of the ultrasonic echo composite at the current sampling time is calculated, and the expression is: in, Indicates the synthetic aperture number n During the next transmission, the beamformer at the pixel point The final ultrasonic echo composite Pearson weighted coefficients were obtained.

2. The ultrasound imaging method according to claim 1, characterized in that, In step S5, the single-frame imaging sub-image in single-transmission all-reception mode is obtained, and its expression is: in, Indicates the first n With multiple emission apertures, the adaptive beamformer based on the Pearson weighting coefficient of the dual-element array achieves pixel-level accuracy in the detection region. The output value, This indicates the pixel number of the original beamformer DAS in the detection area. The output value.

3. The ultrasound imaging method according to claim 2, characterized in that, In step S6, the ultrasound imaging result is obtained, expressed as: in, This indicates that in synthetic aperture mode, the adaptive beamformer based on Pearson weighting coefficients of the two-sided array elements achieves high performance at the pixel level. The final output value; This indicates a summation operation.

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