Ultrasonic elastography system and method based on local least square fitting operator

Abstract

The invention relates to an ultrasonic elastography system and method based on a local least square fitting operator. Comprising the following steps: acquiring a plurality of wave fields under a target frequency based on spatio-temporal data of ultrasonic shear wave propagation; obtaining a relative coordinate matrix based on the fitting matrix; obtaining a fitting operator matrix based on the relative coordinate matrix and a least square principle; for each pixel of the complex wave field, extracting a local complex data block taking the pixel as a center; acquiring relative phase vectors respectively corresponding to the plurality of local complex data blocks; on the basis of the fitting operator matrix and the relative phase vectors corresponding to the multiple local complex data blocks, fitting wave number components corresponding to the multiple local complex data blocks are obtained; and on the basis of the fitting wave number components corresponding to the plurality of local complex data blocks, shear wave velocities corresponding to the plurality of local complex data blocks are obtained, and then an elastic graph is obtained. According to the method, random noise can be effectively suppressed in a phase gradient calculation stage, and a fine edge structure of a tissue is reserved.

Description

Technical Field

[0001] Several embodiments of this specification relate to the field of ultrasonic shear wave elastography technology, specifically to ultrasonic elastography systems and methods based on local least squares fitting operators. Background Technology

[0002] Shear wave elastography (SWE) quantitatively assesses tissue stiffness by measuring the propagation velocity of shear waves within the tissue. Among existing reconstruction algorithms, the frequency phase gradient (FPG) method is a mainstream technique.

[0003] Limitations of existing technology:

[0004] 1. Traditional FPG gradient calculation is fragile: Traditional FPG methods typically use finite differences (such as the gradient function in MATLAB) of discrete data to calculate the spatial gradient of the phase. This method only uses two adjacent pixels for calculation and is extremely sensitive to phase noise.

[0005] 2. Disadvantages of post-processing smoothing: To reduce noise, existing techniques typically perform large-window median filtering or Gaussian smoothing after calculating the velocity map. While this "calculate first, smooth later" approach reduces noise, it also severely blurs the edge details of lesions and reduces spatial resolution.

[0006] 3. Limitations of the TPM method: The existing Tangent Plane Method (TPM) is mainly applied to time-of-flight surface fitting in the time domain. Although it has good noise resistance, it is easily affected by waveform distortion and multipath reflection when processed directly in the time domain, and the computational cost is relatively large.

[0007] Therefore, there is an urgent need for an ultrasound elastography method that can effectively suppress random noise during the phase gradient calculation stage while preserving the fine edge structure of the tissue. Summary of the Invention

[0008] This specification provides an ultrasound elastography system and method based on a local least squares fitting operator, which can effectively suppress random noise during the phase gradient calculation stage while preserving the fine edge structure of the tissue.

[0009] The technical solution is as follows:

[0010] In a first aspect, embodiments of this specification provide an ultrasonic elastography system based on a local least squares fitting operator, comprising:

[0011] The first acquisition module acquires the spatiotemporal data of ultrasonic shear wave propagation and obtains the complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation.

[0012] The first matrix generation module has a preset size of [size missing]. Fitting matrix And based on the fitting matrix Obtain the relative coordinate matrix , Indicates the number of rows in the matrix. Indicates the number of columns in the matrix. , To iterate through the elements of the fitted matrix row by row from left to right, the traversal reaches the 1st row... The relative position coordinates of the nth array element, if the nth array element is... If the column containing the element is located to the left of the column containing the center element of the fitted matrix, then... for If the first If the column containing the element is located to the right of the column containing the center element of the fitted matrix, then... for , Indicates the first The number of columns between each array element and the center element of the fitted matrix. Indicates horizontal resolution, if the first If the row containing the element of the fitted matrix is ​​located above the row containing the central element of the fitted matrix, then... for If the first If the row containing the element is below the row containing the center element of the fitted matrix, then for , Indicates the first The number of rows between each element and the center element of the fitted matrix. Indicates vertical resolution. Represents the fitting matrix The total number of array elements in the array;

[0013] The second matrix generation module is based on the relative coordinate matrix. The least squares principle is used to obtain the fitting operator matrix;

[0014] The data block acquisition module extracts data centered at each pixel and of size [missing information] for each pixel in the complex wave field. Local complex data blocks;

[0015] The vector acquisition module acquires the relative phase vectors corresponding to each of the multiple local complex data blocks. , Indicates the first The relative phase vectors corresponding to each local complex data block Indicates the first In the local complex data block, the first The local pixel and the first The relative phase difference between the center pixels in a local complex data block Indicates transpose;

[0016] The component acquisition module acquires the fitted wavenumber components corresponding to each of the multiple local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks.

[0017] The graph acquisition module obtains the shear wave velocity corresponding to each of the multiple local complex data blocks based on the fitted wave number components of each block, thereby generating the elasticity graph.

[0018] As a preferred embodiment, the first acquisition module includes a spatiotemporal data acquisition unit, a frequency domain conversion unit, and a complex wave field acquisition unit;

[0019] The spatiotemporal data acquisition unit acquires spatiotemporal data of ultrasonic shear wave propagation;

[0020] The frequency domain transformation unit performs a three-dimensional Fourier transform on the spatiotemporal data to obtain the frequency domain spatiotemporal data;

[0021] The complex wave field acquisition unit uses a directional filter and frequency domain spatiotemporal data to separate a single-direction wave field with a single propagation direction, and obtains the complex wave field at the target frequency after converting it back to the space-frequency domain.

[0022] As a preferred solution, the second matrix generation module is based on the relative coordinate matrix. The fitting operator matrix obtained by the least squares principle .

[0023] As a preferred embodiment, the vector acquisition module includes a first calculation unit, a second calculation unit, and a vector acquisition unit;

[0024] The first computational unit calculates the relative complex values ​​between local pixels in the local complex data block and the center pixel in the local complex data block;

[0025] The second calculation unit calculates the relative phase difference between local pixels in a local complex data block and the center pixel in a local complex data block based on the relative complex values ​​between local pixels in the local complex data block and the center pixel in the local complex data block.

[0026] The vector acquisition unit obtains the relative phase vector corresponding to the local complex data block based on the relative phase difference between each local pixel in the local complex data block and the center pixel in the local complex data block.

[0027] As a preferred embodiment, the component acquisition module acquires the fitted wavenumber components corresponding to each of the multiple local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks, including:

[0028] ;

[0029] in, Indicates the first The horizontal fitted wavenumber components corresponding to each local complex data block Indicates the first The longitudinal fitting wavenumber components correspond to the local complex data blocks.

[0030] As a preferred embodiment, the graph acquisition module includes a wavenumber modulus acquisition unit and a shear wave velocity acquisition unit;

[0031] The wavenumber modulus acquisition unit obtains the wavenumber modulus corresponding to each of the multiple local complex data blocks based on the fitted wavenumber components corresponding to each of the multiple local complex data blocks.

[0032] The shear wave velocity acquisition unit acquires the shear wave velocity corresponding to each of the multiple local complex data blocks based on the wavenumber modulus corresponding to each of the multiple local complex data blocks.

[0033] As a preferred embodiment, the wavenumber modulus acquisition unit obtains the wavenumber modulus corresponding to each of the multiple local complex data blocks based on the fitted wavenumber components corresponding to each of the multiple local complex data blocks, including:

[0034] ;

[0035] in, Indicates the first Wavenumber modulus corresponding to a local complex data block.

[0036] As a preferred embodiment, the shear wave velocity acquisition unit acquires the shear wave velocity corresponding to each of the multiple local complex data blocks based on the wavenumber modulus corresponding to each of the multiple local complex data blocks, including:

[0037] ;

[0038] in, Indicates the first Shear wave velocity corresponding to a local complex data block It represents angular frequency.

[0039] Secondly, embodiments of this specification provide an ultrasonic elastography method based on a local least squares fitting operator, including:

[0040] Spatiotemporal data of ultrasonic shear wave propagation are acquired, and the complex wave field at the target frequency is obtained based on the spatiotemporal data of ultrasonic shear wave propagation.

[0041] Preset size is Fitting matrix And based on the fitting matrix Obtain the relative coordinate matrix , Indicates the number of rows in the matrix. Indicates the number of columns in the matrix. , To iterate through the elements of the fitted matrix row by row from left to right, the traversal reaches the 1st row... The relative position coordinates of the nth array element, if the nth array element is... If the column containing the element is located to the left of the column containing the center element of the fitted matrix, then... for If the first If the column containing the element is located to the right of the column containing the center element of the fitted matrix, then... for , Indicates the first The number of columns between each array element and the center element of the fitted matrix. Indicates horizontal resolution, if the first If the row containing the element of the fitted matrix is ​​located above the row containing the central element of the fitted matrix, then... for If the first If the row containing the element is below the row containing the center element of the fitted matrix, then for , Indicates the first The number of rows between each element and the center element of the fitted matrix. Indicates vertical resolution. Represents the fitting matrix The total number of array elements in the array;

[0042] Based on relative coordinate matrix The least squares principle is used to obtain the fitting operator matrix;

[0043] For each pixel of a complex wave field, extract the image centered at that pixel with a size of [missing value]. Local complex data blocks;

[0044] The vector acquisition module acquires the relative phase vectors corresponding to each of the multiple local complex data blocks. , Indicates the first The relative phase vectors corresponding to each local complex data block Indicates the first In the local complex data block, the first The local pixel and the first The relative phase difference between the center pixels in a local complex data block Indicates transpose;

[0045] Based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks, the fitted wavenumber components corresponding to each of the multiple local complex data blocks are obtained;

[0046] Based on the fitted wavenumber components corresponding to each of the multiple local complex data blocks, the shear wave velocity corresponding to each of the multiple local complex data blocks is obtained, and thus the elasticity map is obtained.

[0047] As a preferred embodiment, the step of acquiring spatiotemporal data of ultrasonic shear wave propagation and obtaining the complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation includes:

[0048] Acquire spatiotemporal data of ultrasonic shear wave propagation;

[0049] Perform a three-dimensional Fourier transform on the spatiotemporal data to obtain frequency domain spatiotemporal data;

[0050] By using directional filters and frequency-domain spatiotemporal data, a single-directional wave field with a single propagation direction is obtained, and after conversion back to the space-frequency domain, a complex wave field at the target frequency is obtained.

[0051] Thirdly, embodiments of this specification provide an electronic device, including a processor and a memory; the processor is connected to the memory; the memory is used to store executable program code; the processor reads the executable program code stored in the memory to run a program corresponding to the executable program code, so as to perform the steps described in the second aspect of the above embodiments.

[0052] Fourthly, embodiments of this specification provide a computer storage medium storing a plurality of instructions adapted for loading by a processor and executing the steps described in the second aspect of the above embodiments.

[0053] The beneficial effects of the technical solutions provided in some embodiments of this specification include at least the following:

[0054] In the frequency domain phase gradient calculation step, the local least squares fitting operator is used to replace the finite difference operation to calculate the phase gradient of the complex wave field. This effectively suppresses random noise during the phase gradient calculation stage, and better preserves the image's edge resolution compared to calculating a noisy velocity map first and then performing Gaussian smoothing. Furthermore, the local least squares fitting operator is a pre-calculated matrix, and only simple matrix multiplication is involved in actual processing, avoiding the problem of increased computational load.

[0055] Before applying the local least squares fitting operator, the complex phase difference between each pixel in the local complex data block and the center pixel is calculated to avoid periodic jumps in phase values.

[0056] The time-domain plane fitting concept of the tangent plane method (TPM) is applied to the frequency-domain single-frequency wave field after directional filtering to achieve direct and robust estimation of the wave number vector. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 A flowchart illustrating an adaptive granularity adjustment method for generating urban sound environment profiles according to some embodiments of this disclosure is shown.

[0059] Figure 2 The fitting matrix is ​​shown. A schematic diagram showing the relative position coordinates of each array element.

[0060] Figure 3 This diagram illustrates the principle of phase gradient calculation using the finite difference method.

[0061] Figure 4 The diagram illustrates the principle of phase gradient calculation using the local least squares fitting method.

[0062] Figure 5 A schematic flowchart of an ultrasound elastography method based on a local least squares fitting operator, according to some embodiments of this disclosure, is shown.

[0063] Figure 6 A schematic block diagram of an electronic device according to some embodiments of the present disclosure is shown. Detailed Implementation

[0064] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings.

[0065] The terms "first," "second," "third," etc., in the description, claims, and accompanying drawings are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus.

[0066] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this specification. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0067] Figure 1 A schematic diagram of the structure of an ultrasonic elastography system based on a local least squares fitting operator, according to some embodiments of this disclosure, is shown. Figure 1 As shown, an ultrasound elastography system based on a local least squares fitting operator can include at least:

[0068] The first acquisition module acquires the spatiotemporal data of ultrasonic shear wave propagation and obtains the complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation.

[0069] The first matrix generation module has a preset size of [size missing]. Fitting matrix And based on the fitting matrix Obtain the relative coordinate matrix , Indicates the number of rows in the matrix. Indicates the number of columns in the matrix. , To iterate through the elements of the fitted matrix row by row from left to right, the traversal reaches the 1st row... The relative position coordinates of the nth array element, if the nth array element is... If the column containing the element is located to the left of the column containing the center element of the fitted matrix, then... for If the first If the column containing the element is located to the right of the column containing the center element of the fitted matrix, then... for , Indicates the first The number of columns between each array element and the center element of the fitted matrix. Indicates horizontal resolution, if the first If the row containing the element of the fitted matrix is ​​located above the row containing the central element of the fitted matrix, then... for If the first If the row containing the element is below the row containing the center element of the fitted matrix, then for , Indicates the first The number of rows between each element and the center element of the fitted matrix. Indicates vertical resolution. Represents the fitting matrix The total number of array elements in the array;

[0070] The second matrix generation module is based on the relative coordinate matrix. The least squares principle is used to obtain the fitting operator matrix;

[0071] The data block acquisition module extracts data centered at each pixel and of size [missing information] for each pixel in the complex wave field. Local complex data blocks (Note: If it is not possible to directly extract a block of size for a specific pixel) A local complex data block can be used to extend the edges around the pixel and assign fixed values ​​to the extended positions, thereby achieving a size of Extracting local complex data blocks; or you can directly discard those that cannot be directly extracted and are of a size of [size missing]. (pixels of a local complex data block).

[0072] The vector acquisition module acquires the relative phase vectors corresponding to each of the multiple local complex data blocks. , Indicates the first The relative phase vectors corresponding to each local complex data block Indicates the first In the local complex data block, the first The local pixel and the first The relative phase difference between the center pixels in a local complex data block Indicates transpose;

[0073] The component acquisition module acquires the fitted wavenumber components corresponding to each of the multiple local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks.

[0074] The graph acquisition module obtains the shear wave velocity corresponding to each of the multiple local complex data blocks based on the fitted wave number components of each block, thereby generating the elasticity graph.

[0075] The first acquisition module includes a spatiotemporal data acquisition unit, a frequency domain conversion unit, and a complex wave field acquisition unit;

[0076] The spatiotemporal data acquisition unit acquires spatiotemporal data of ultrasonic shear wave propagation. , Indicates vertical position. Indicates horizontal position. Indicates time;

[0077] The frequency domain transformation unit performs a three-dimensional Fourier transform on the spatiotemporal data to obtain the frequency domain spatiotemporal data. , Indicates the longitudinal wave number, Indicates the horizontal wavenumber. Indicates angular frequency;

[0078] The complex wave field acquisition unit uses a directional filter and frequency domain spatiotemporal data to separate a single-direction wave field with a single propagation direction, and obtains the complex wave field at the target frequency after converting it back to the space-frequency domain.

[0079] Figure 2 The fitting matrix is ​​shown. A schematic diagram showing the relative position coordinates of each array element. Figure 2 (An example using a 3x3 matrix is ​​provided). Understandably, the fitted matrix is ​​traversed row by row from left to right, and the relative position coordinates of the first element encountered are... The relative position coordinates of the second array element are: The relative position coordinates of the third array element are: The relative position coordinates of the 4th array element are The relative position coordinates of the 5th array element are The relative position coordinates of the 6th array element are The relative position coordinates of the 7th array element are The relative position coordinates of the 8th array element are: The relative position coordinates of the 9th array element are .in, Figure 2 The center position of the fitted matrix shown is the position of the element corresponding to the 5th element.

[0080] Taking the relative position coordinates of the first array element encountered during the traversal as an example, since the column containing the first array element is located to the left of the column containing the center array element of the fitted matrix, and there is a one-column gap, then... for Since the row containing the first element is located above the row containing the center element of the fitted matrix, and there is a one-row gap, then... for Therefore, the relative position coordinates of the first array element are .

[0081] Furthermore, taking the relative position coordinates of the 9th array element as an example, since the column containing the 9th array element is located to the right of the column containing the center array element of the fitted matrix, and is separated by one column, then... for Since the row containing the 9th element is located below the row containing the center element of the fitted matrix, and there is a one-row gap, then... for Therefore, the relative position coordinates of the 9th array element are .

[0082] in, , .

[0083] In some embodiments of this specification, the second matrix generation module is based on a relative coordinate matrix. The fitting operator matrix obtained by the least squares principle .

[0084] In some embodiments of this specification, the vector acquisition module includes a first calculation unit, a second calculation unit, and a vector acquisition unit;

[0085] The first computational unit calculates the relative complex values ​​between local pixels in the local complex data block and the center pixel in the local complex data block;

[0086] The second calculation unit calculates the relative phase difference between local pixels in a local complex data block and the center pixel in a local complex data block based on the relative complex values ​​between local pixels in the local complex data block and the center pixel in the local complex data block.

[0087] The vector acquisition unit obtains the relative phase vector corresponding to the local complex data block based on the relative phase difference between each local pixel in the local complex data block and the center pixel in the local complex data block.

[0088] Let the first The complex value of the center pixel in each local complex data block is: , No. In the local complex data block, the first The complex value of each local pixel is , No. In the local complex data block, the first The local pixel and the first The formula for calculating the relative complex values ​​between the center pixels in a local complex data block is:

[0089] ;

[0090] in, Indicates the first In the local complex data block, the first The local pixel and the first The relative complex values ​​between the center pixels in a local complex data block Indicates conjugate.

[0091] No. In the local complex data block, the first The local pixel and the first The formula for calculating the relative phase difference between the center pixels in a local complex data block is:

[0092] ;

[0093] in, Indicates the first In the local complex data block, the first The local pixel and the first The relative phase difference between the center pixels in a local complex data block This represents the phase angle function.

[0094] Therefore, the first The relative phase vector corresponding to each local complex data block It can be represented as:

[0095] ;

[0096] The relative phase vector acquisition method described in the embodiments of this specification does not require a complex unwinding algorithm, and can ensure that the phase is continuous within a local complex data block (local window), thus avoiding the problems caused by directly extracting the phase. Phase wrapping problem.

[0097] In some embodiments of this specification, the component acquisition module acquires the fitted wavenumber components corresponding to each of the multiple local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks, including:

[0098] ;

[0099] in, Indicates the first The horizontal fitted wavenumber components corresponding to each local complex data block Indicates the first The longitudinal fitting wavenumber components correspond to the local complex data blocks.

[0100] In some embodiments of this specification, the graph acquisition module includes a wavenumber modulus acquisition unit and a shear wave velocity acquisition unit;

[0101] The wavenumber modulus acquisition unit obtains the wavenumber modulus corresponding to each of the multiple local complex data blocks based on the fitted wavenumber components corresponding to each of the multiple local complex data blocks.

[0102] The shear wave velocity acquisition unit acquires the shear wave velocity corresponding to each of the multiple local complex data blocks based on the wavenumber modulus corresponding to each of the multiple local complex data blocks.

[0103] The wavenumber modulus acquisition unit obtains the wavenumber modulus corresponding to each of the multiple local complex data blocks based on the fitted wavenumber components, including:

[0104] ;

[0105] in, Indicates the first Wavenumber modulus corresponding to a local complex data block.

[0106] The shear wave velocity acquisition unit acquires the shear wave velocity corresponding to each of the multiple local complex data blocks based on the wavenumber modulus of each block, including:

[0107] ;

[0108] in, Indicates the first Shear wave velocity corresponding to a local complex data block It represents angular frequency.

[0109] In the examples described in this specification:

[0110] In the frequency domain phase gradient calculation step, the local least squares fitting operator is used to replace the finite difference operation to calculate the phase gradient of the complex wave field. This effectively suppresses random noise during the phase gradient calculation stage, and compared to calculating a noisy velocity map first and then performing Gaussian smoothing, it better preserves the edge resolution of the image (Note: see reference). Figure 3 , Figure 4 As shown, it can be seen that using the local least squares fitting method described in the embodiments of this specification for phase gradient calculation results in a more robust phase gradient due to the utilization of more point data; using finite difference operations for phase gradient calculation, based on... Figure 3As shown, it only uses data from two adjacent points, that is... Figure 3 Points shown as well as Furthermore, the local least squares fitting operator is a pre-calculated matrix, and the actual processing only involves simple matrix multiplication, thus avoiding the problem of increased computational load.

[0111] Before applying the local least squares fitting operator, the complex phase difference between each pixel in the local complex data block and the center pixel is calculated to avoid periodic jumps in phase values.

[0112] The time-domain plane fitting concept of the tangent plane method (TPM) is applied to the frequency-domain single-frequency wave field after directional filtering to achieve direct and robust estimation of the wave number vector.

[0113] Figure 5 The following are schematic flowcharts illustrating some embodiments of the ultrasonic elastography method based on the local least squares fitting operator. The various embodiments in this specification are described in a progressive manner, with reference to each other for similar or identical parts. Each embodiment focuses on describing the differences from other embodiments. In particular, the ultrasonic elastography method embodiments are basically similar to the ultrasonic elastography system embodiments, so the description is relatively simple; relevant details can be found in the descriptions of the ultrasonic elastography system embodiments.

[0114] Furthermore, it should be understood that the numbers in the flowchart of the method do not indicate the order in which these steps are executed. Some or all of these steps can be executed in parallel, or their execution order can be interchanged, and this disclosure does not impose any restrictions in this regard. Figure 5 The methods described may also include additional steps not shown and / or the steps shown may be omitted, and the scope of this disclosure is not limited in this respect.

[0115] like Figure 5 As shown, the ultrasound elastography method based on the local least squares fitting operator can include at least:

[0116] Step 502: Obtain the spatiotemporal data of ultrasonic shear wave propagation, and obtain the complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation.

[0117] Step 504, preset size is Fitting matrix And based on the fitting matrix Obtain the relative coordinate matrix , Indicates the number of rows in the matrix. Indicates the number of columns in the matrix. , To iterate through the elements of the fitted matrix row by row from left to right, the traversal reaches the 1st row... The relative position coordinates of the nth array element, if the nth array element is... If the column containing the element is located to the left of the column containing the center element of the fitted matrix, then... for If the first If the column containing the element is located to the right of the column containing the center element of the fitted matrix, then... for , Indicates the first The number of columns between each array element and the center element of the fitted matrix. Indicates horizontal resolution, if the first If the row containing the element of the fitted matrix is ​​located above the row containing the central element of the fitted matrix, then... for If the first If the row containing the element is below the row containing the center element of the fitted matrix, then for , Indicates the first The number of rows between each element and the center element of the fitted matrix. Indicates vertical resolution. Represents the fitting matrix The total number of array elements in the array;

[0118] Step 506: Based on the relative coordinate matrix The least squares principle is used to obtain the fitting operator matrix;

[0119] Step 508: For each pixel of the complex wave field, extract the image centered at that pixel and of size [missing information]. Local complex data blocks;

[0120] Step 510: Obtain the relative phase vectors corresponding to each of the multiple local complex data blocks. , Indicates the first The relative phase vectors corresponding to each local complex data block Indicates the first In the local complex data block, the first The local pixel and the first The relative phase difference between the center pixels in a local complex data block Indicates transpose;

[0121] Step 512: Based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks, obtain the fitted wavenumber components corresponding to each of the multiple local complex data blocks;

[0122] Step 514: Based on the fitted wavenumber components corresponding to each of the multiple local complex data blocks, obtain the shear wave velocity corresponding to each of the multiple local complex data blocks, and then obtain the elasticity map.

[0123] In some embodiments of this specification, acquiring spatiotemporal data of ultrasonic shear wave propagation and obtaining a complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation includes:

[0124] Step 5022: Obtain spatiotemporal data of ultrasonic shear wave propagation;

[0125] Step 5024: Perform a three-dimensional Fourier transform on the spatiotemporal data to obtain frequency domain spatiotemporal data;

[0126] Step 5026: Using a directional filter and frequency domain spatiotemporal data, a single-direction wave field with a single propagation direction is obtained, and after conversion back to the space-frequency domain, a complex wave field at the target frequency is obtained.

[0127] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this specification are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., Digital Versatile Discs (DVDs)), or semiconductor media (e.g., Solid State Disks (SSDs)).

[0128] Figure 6 A block diagram of an electronic device 600 that can implement various embodiments of the present disclosure is shown. For example... Figure 6As shown, the electronic device 600 includes a processor 610, a disk drive 620, an input / output interface 630, a network interface 640, and a memory 650. The processor 610, disk drive 620, input / output interface 630, network interface 640, and memory 650 can communicate with each other via a communication bus 660.

[0129] The processor 610 can be implemented using a general-purpose CPU, microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits to execute relevant programs and implement the technical solution provided in this application.

[0130] The memory 650 can be implemented in the form of ROM (Read Only Memory), RAM (Read Access Memory), static memory, dynamic storage devices, etc. The memory 650 can store the operating system 651 for controlling the operation of the electronic device 600, and the basic input / output system (BIOS) 652 for controlling the low-level operations of the electronic device 600. Additionally, it can store a web browser 653, a data storage management system 654, etc. In summary, when implementing the technical solution provided in this application through software or firmware, the relevant program code is stored in the memory 650 and is called and executed by the processor 610.

[0131] The input / output interface 630 is used to connect input / output modules to enable information input and output. Input / output modules can be configured as components within the device (not shown in the figure) or externally connected to the device to provide corresponding functions. Input devices may include keyboards, mice, touchscreens, microphones, various sensors, etc., while output devices may include displays, speakers, vibrators, indicator lights, etc.

[0132] Network interface 640 is used to connect a communication module (not shown in the figure) to enable communication and interaction between the device and other devices. The communication module can communicate via wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0133] Bus 660 includes a pathway for transmitting information between various components of the device, such as processor 610, disk drive 620, input / input interface 630, network interface 640, and memory 650.

[0134] It should be noted that although the above-described device only shows the processor 610, disk drive 620, input / output interface 630, network interface 640, memory 650, bus 660, etc., in specific implementations, the device may also include other components necessary for normal operation. Furthermore, those skilled in the art will understand that the above-described device may only include the components necessary for implementing the method of this application, and does not necessarily include all the components shown in the figures.

[0135] The program code used to implement the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0136] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. Furthermore, although operations are depicted in a specific order, this should be understood as requiring that such operations be performed in the specific order shown or in sequential order, or requiring that all illustrated operations be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0137] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. An ultrasonic elastography system based on a local least squares fitting operator, characterized in that, include: The first acquisition module acquires the spatiotemporal data of ultrasonic shear wave propagation and obtains the complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation. The first matrix generation module has a preset size of [size missing]. Fitting matrix And based on the fitting matrix Obtain the relative coordinate matrix , Indicates the number of rows in the matrix. Indicates the number of columns in the matrix. , To iterate through the elements of the fitted matrix row by row from left to right, the traversal reaches the 1st row... The relative position coordinates of the nth array element, if the nth array element is... If the column containing the element is located to the left of the column containing the center element of the fitted matrix, then... for If the first If the column containing the element is located to the right of the column containing the center element of the fitted matrix, then... for , Indicates the first The number of columns between each array element and the center element of the fitted matrix. Indicates the horizontal resolution, if the first If the row containing the element of the fitted matrix is ​​located above the row containing the central element of the fitted matrix, then... for If the first If the row containing the element is below the row containing the center element of the fitted matrix, then for , Indicates the first The number of rows between each element and the center element of the fitted matrix. Indicates vertical resolution. Represents the fitting matrix The total number of array elements in the array; The second matrix generation module is based on the relative coordinate matrix. The least squares principle is used to obtain the fitting operator matrix; The data block acquisition module extracts data centered at each pixel and of size [missing information] for each pixel in the complex wave field. Local complex data blocks; The vector acquisition module acquires the relative phase vectors corresponding to each of the multiple local complex data blocks. , Indicates the first The relative phase vectors corresponding to each local complex data block Indicates the first In the local complex data block, the first The local pixel and the first The relative phase difference between the center pixels in a local complex data block Indicates transpose; The component acquisition module acquires the fitted wavenumber components corresponding to each of the multiple local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks. The graph acquisition module obtains the shear wave velocity corresponding to each of the multiple local complex data blocks based on the fitted wave number components of each block, thereby generating the elasticity graph.

2. The ultrasonic elastography system based on local least squares fitting operator according to claim 1, characterized in that, The first acquisition module includes a spatiotemporal data acquisition unit, a frequency domain conversion unit, and a complex wave field acquisition unit; The spatiotemporal data acquisition unit acquires spatiotemporal data of ultrasonic shear wave propagation; The frequency domain transformation unit performs a three-dimensional Fourier transform on the spatiotemporal data to obtain the frequency domain spatiotemporal data; The complex wave field acquisition unit uses a directional filter and frequency domain spatiotemporal data to separate a single-direction wave field with a single propagation direction, and obtains the complex wave field at the target frequency after converting it back to the space-frequency domain.

3. The ultrasonic elastography system based on local least squares fitting operator according to claim 1, characterized in that, The second matrix generation module is based on relative coordinate matrices. The fitting operator matrix obtained by the least squares principle .

4. The ultrasonic elastography system based on local least squares fitting operator according to claim 1, characterized in that, The vector acquisition module includes a first calculation unit, a second calculation unit, and a vector acquisition unit; The first computational unit calculates the relative complex values ​​between local pixels in the local complex data block and the center pixel in the local complex data block; The second calculation unit calculates the relative phase difference between local pixels in a local complex data block and the center pixel in a local complex data block based on the relative complex values ​​between local pixels in the local complex data block and the center pixel in the local complex data block. The vector acquisition unit obtains the relative phase vector corresponding to the local complex data block based on the relative phase difference between each local pixel in the local complex data block and the center pixel in the local complex data block.

5. The ultrasonic elastography system based on local least squares fitting operator according to claim 3, characterized in that, The component acquisition module obtains the fitted wavenumber components corresponding to each of the multiple local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to each local complex data block, including: ； in, Indicates the first The horizontal fitted wavenumber components corresponding to each local complex data block Indicates the first The longitudinal fitting wavenumber components correspond to the local complex data blocks.

6. The ultrasonic elastography system based on local least squares fitting operator according to claim 5, characterized in that, The image acquisition module includes a wavenumber modulus acquisition unit and a shear wave velocity acquisition unit; The wavenumber modulus acquisition unit obtains the wavenumber modulus corresponding to each of the multiple local complex data blocks based on the fitted wavenumber components corresponding to each of the multiple local complex data blocks. The shear wave velocity acquisition unit acquires the shear wave velocity corresponding to each of the multiple local complex data blocks based on the wavenumber modulus corresponding to each of the multiple local complex data blocks.

7. The ultrasonic elastography system based on local least squares fitting operator according to claim 6, characterized in that, The wavenumber modulus acquisition unit obtains the wavenumber modulus corresponding to each of the multiple local complex data blocks based on the fitted wavenumber components, including: ； in, Indicates the first Wavenumber modulus corresponding to a local complex data block.

8. The ultrasonic elastography system based on local least squares fitting operator according to claim 7, characterized in that, The shear wave velocity acquisition unit acquires the shear wave velocity corresponding to each of the multiple local complex data blocks based on the wavenumber modulus of each block, including: ； in, Indicates the first Shear wave velocity corresponding to a local complex data block It represents angular frequency.

9. An ultrasonic elastography method based on local least squares fitting operator, based on the ultrasonic elastography system based on local least squares fitting operator according to any one of claims 1 to 8, characterized in that, include: Spatiotemporal data of ultrasonic shear wave propagation are acquired, and the complex wave field at the target frequency is obtained based on the spatiotemporal data of ultrasonic shear wave propagation. Preset size is Fitting matrix And based on the fitting matrix Obtain the relative coordinate matrix , Indicates the number of rows in the matrix. Indicates the number of columns in the matrix. , To iterate through the elements of the fitted matrix row by row from left to right, the traversal reaches the 1st row... The relative position coordinates of the nth array element, if the nth array element is... If the column containing the element is located to the left of the column containing the center element of the fitted matrix, then... for If the first If the column containing the element is located to the right of the column containing the center element of the fitted matrix, then... for , Indicates the first The number of columns between each array element and the center element of the fitted matrix. Indicates the horizontal resolution, if the first If the row containing the element of the fitted matrix is ​​located above the row containing the central element of the fitted matrix, then... for If the first If the row containing the element is below the row containing the center element of the fitted matrix, then for , Indicates the first The number of rows between each element and the center element of the fitted matrix. Indicates vertical resolution. Represents the fitting matrix The total number of array elements in the array; Based on relative coordinate matrix The least squares principle is used to obtain the fitting operator matrix; For each pixel of a complex wave field, extract the image centered at that pixel with a size of [missing value]. Local complex data blocks; The vector acquisition module acquires the relative phase vectors corresponding to each of the multiple local complex data blocks. , Indicates the first The relative phase vectors corresponding to each local complex data block Indicates the first In the local complex data block, the first The local pixel and the first The relative phase difference between the center pixels in a local complex data block Indicates transpose; Based on the fitting operator matrix and the relative phase vectors corresponding to each of the multiple local complex data blocks, the fitted wavenumber components corresponding to each of the multiple local complex data blocks are obtained; Based on the fitted wavenumber components corresponding to each of the multiple local complex data blocks, the shear wave velocity corresponding to each of the multiple local complex data blocks is obtained, and thus the elasticity map is obtained.

10. The ultrasonic elastography method based on local least squares fitting operator according to claim 9, characterized in that, The process of acquiring spatiotemporal data of ultrasonic shear wave propagation and obtaining the complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation includes: Acquire spatiotemporal data of ultrasonic shear wave propagation; Perform a three-dimensional Fourier transform on the spatiotemporal data to obtain frequency domain spatiotemporal data; By using directional filters and frequency-domain spatiotemporal data, a single-direction wave field with a single propagation direction is obtained, and after conversion back to the space-frequency domain, a complex wave field at the target frequency is obtained.

Images