CN-122004918-A - Ultrasonic elastography system and method based on local least square fitting operator

CN122004918ACN 122004918 ACN122004918 ACN 122004918ACN-122004918-A

Abstract

The invention relates to an ultrasonic elastography system and method based on a local least squares fitting operator. The method comprises the steps of obtaining a complex wave field under a target frequency based on space-time data of ultrasonic shear wave propagation, obtaining a relative coordinate matrix based on a fitting matrix, obtaining a fitting operator matrix based on the relative coordinate matrix and a least square principle, extracting local complex data blocks taking the pixel as a center for each pixel of the complex wave field, obtaining relative phase vectors corresponding to the local complex data blocks, obtaining fitting wave number components corresponding to the local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to the local complex data blocks, obtaining shear wave speeds corresponding to the local complex data blocks based on the fitting wave number components corresponding to the local complex data blocks, and further obtaining an elastic diagram. The invention can effectively inhibit random noise in the phase gradient calculation stage, and simultaneously preserve the fine edge structure of the tissue.

Inventors

MA ZHICHUAN

Assignees

聚融医疗科技(杭州)有限公司

Dates

Publication Date: 20260512
Application Date: 20260120

Claims (10)

1. An ultrasound elastography system based on a local least squares fitting operator, comprising: the first acquisition module acquires the space-time data of ultrasonic shear wave propagation and acquires a complex wave field under the target frequency based on the space-time data of ultrasonic shear wave propagation; The first matrix generation module is preset as follows Fitting matrix of (a) And based on a fitting matrix Acquiring a relative coordinate matrix , Representing the number of rows of the matrix, Representing the number of columns of the matrix, , To traverse the array elements of the fitting matrix row by row from left to right, the traversed first Relative position coordinates corresponding to each array element, if The array of each array element is positioned at the left side of the array of the fitting matrix center array element Is that If at first The array of each array element is positioned at the right side of the array of the central array element of the fitting matrix Is that , Represent the first Array elements and fitting matrix the number of spaced rows of the central array element, Represents the lateral resolution, if The array elements are arranged on the upper side of the array elements in the center of the fitting matrix Is that If at first The array elements are arranged at the lower side of the array elements in the center of the fitting matrix Is that , Represent the first The number of interval rows between each array element and the array element in the center of the fitting matrix, The longitudinal resolution is indicated as such, Representing fitting matrices The total number of array elements in the matrix; The second matrix generation module is based on a relative coordinate matrix Obtaining a fitting operator matrix according to a least square principle; A data block acquisition module for extracting, for each pixel of the complex wavefield, a pixel centered on the pixel and of a size Is a local complex data block; the vector acquisition module acquires relative phase vectors corresponding to the local complex data blocks , Represent the first The relative phase vectors corresponding to the partial complex data blocks, Represent the first The first of the partial complex data blocks Local pixel and the first The relative phase difference between the center pixels in the local complex data blocks, Representing a transpose; The component acquisition module is used for acquiring fitting wave number components corresponding to the local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to the local complex data blocks; The image acquisition module is used for acquiring shear wave speeds corresponding to the local complex data blocks based on fitting wave number components corresponding to the local complex data blocks, so as to obtain an elastic image.
2. The ultrasonic elastography system based on the local least squares fitting operator according to claim 1, wherein the first acquisition module comprises a spatio-temporal data acquisition unit, a frequency domain conversion unit, a complex wave field acquisition unit; a space-time data acquisition unit for acquiring space-time data of ultrasonic shear wave propagation; the frequency domain conversion unit performs three-dimensional Fourier transform on the time-space data to obtain frequency domain time-space data; And the complex wave field acquisition unit adopts a direction filter and frequency domain space-time data to separate and obtain a single-direction wave field with a single propagation direction, and converts back to a space-frequency domain to obtain a complex wave field under a target frequency.
3. The ultrasonic elastography system based on the partial least squares fitting operator according to claim 1, wherein the second matrix generation module is based on a relative coordinate matrix Fitting operator matrix obtained by least square principle 。
4. The ultrasonic elastography system based on the local least squares fitting operator according to claim 1, wherein the vector acquisition module comprises a first calculation unit, a second calculation unit, and a vector acquisition unit; a first calculation unit that calculates a relative complex value between a local pixel in the local complex data block and a center pixel in the local complex data block; a second calculation unit that calculates a relative phase difference between the local pixel in the local complex data block and the center pixel in the local complex data block based on a relative complex value between the local pixel in the local complex data block and the center pixel in the local complex data block; And the vector acquisition unit is used for acquiring a 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 central pixel in the local complex data block.
5. The ultrasonic elastography system based on the partial least squares fitting operator according to claim 3, wherein the component obtaining module obtains fitting wave number components corresponding to each of the plurality of partial complex data blocks based on the fitting operator matrix and relative phase vectors corresponding to each of the plurality of partial complex data blocks, comprising: ; Wherein, the Represent the first Fitting wave number components in the horizontal direction corresponding to the local complex data blocks, Represent the first The wave number components are fitted to the corresponding longitudinal directions of the local complex data blocks.
6. The ultrasonic elastography system based on the local least squares fitting operator according to claim 5, wherein the graph acquisition module comprises a wave number module length acquisition unit and a shear wave velocity acquisition unit; The wave number module length obtaining unit obtains wave number module lengths corresponding to the local complex data blocks based on fitting wave number components corresponding to the local complex data blocks; And a shear wave velocity acquisition unit for acquiring shear wave velocities corresponding to the local complex data blocks based on wave number mode lengths corresponding to the local complex data blocks.
7. The ultrasonic elastography system based on the partial least squares fitting operator according to claim 6, wherein the wave number module length obtaining unit obtains wave number module lengths corresponding to each of the plurality of partial complex data blocks based on fitting wave number components corresponding to each of the plurality of partial complex data blocks, comprising: ; Wherein, the Represent the first Wave number mode length corresponding to each local complex data block.
8. The ultrasonic elastography system based on the partial least squares fitting operator according to claim 7, wherein the acquiring of the shear wave velocity based on the wave number mode length corresponding to each of the plurality of partial complex data blocks in the shear wave velocity acquiring unit comprises: ; Wherein, the Represent the first Shear wave velocities corresponding to the local complex data blocks, Indicating the angular frequency.
9. An ultrasonic elastography method based on a local least squares fitting operator, based on the ultrasonic elastography system based on the local least squares fitting operator as set forth in any one of claims 1-8, comprising: Acquiring space-time data of ultrasonic shear wave propagation, and acquiring a complex wave field under a target frequency based on the space-time data of ultrasonic shear wave propagation; the preset size is Fitting matrix of (a) And based on a fitting matrix Acquiring a relative coordinate matrix , Representing the number of rows of the matrix, Representing the number of columns of the matrix, , To traverse the array elements of the fitting matrix row by row from left to right, the traversed first Relative position coordinates corresponding to each array element, if The array of each array element is positioned at the left side of the array of the fitting matrix center array element Is that If at first The array of each array element is positioned at the right side of the array of the central array element of the fitting matrix Is that , Represent the first Array elements and fitting matrix the number of spaced rows of the central array element, Represents the lateral resolution, if The array elements are arranged on the upper side of the array elements in the center of the fitting matrix Is that If at first The array elements are arranged at the lower side of the array elements in the center of the fitting matrix Is that , Represent the first The number of interval rows between each array element and the array element in the center of the fitting matrix, The longitudinal resolution is indicated as such, Representing fitting matrices The total number of array elements in the matrix; Based on relative coordinate matrix Obtaining a fitting operator matrix according to a least square principle; extracting, for each pixel of the complex wavefield, a pixel centered on the pixel and of a size Is a local complex data block; the vector acquisition module acquires relative phase vectors corresponding to the local complex data blocks , Represent the first The relative phase vectors corresponding to the partial complex data blocks, Represent the first The first of the partial complex data blocks Local pixel and the first The relative phase difference between the center pixels in the local complex data blocks, Representing a transpose; Based on the fitting operator matrix and the relative phase vectors corresponding to the local complex data blocks, fitting wave number components corresponding to the local complex data blocks are obtained; And acquiring shear wave speeds corresponding to the local complex data blocks based on fitting wave number components corresponding to the local complex data blocks, so as to obtain an elastic diagram.
10. The ultrasonic elastography method based on the partial least squares fitting operator according to claim 9, wherein the acquiring the spatiotemporal data of ultrasonic shear wave propagation and acquiring the complex wave field at the target frequency based on the spatiotemporal data of ultrasonic shear wave propagation comprises: acquiring space-time data of ultrasonic shear wave propagation; performing three-dimensional Fourier transform on the space-time data to obtain frequency domain space-time data; and separating by adopting a direction filter and frequency domain space-time data to obtain a single-direction wave field in a single propagation direction, and converting back to a space-frequency domain to obtain a complex wave field under the target frequency.

Description

Ultrasonic elastography system and method based on local least square fitting operator Technical Field Embodiments of the present disclosure relate to the field of ultrasound shear wave elastography, and in particular, to an ultrasound elastography system and method based on a local least squares fitting operator. Background Ultrasonic shear wave elastography (SHEAR WAVE Elastography, SWE) quantitatively evaluates the stiffness of tissue by measuring the propagation velocity of shear waves in the tissue. Among existing reconstruction algorithms, frequency domain phase gradient method (Frequency PHASE GRADIENT, FPG) is a mainstream technology. Limitations of the prior art: 1. gradient computation of conventional FPG is vulnerable-conventional FPG methods typically use finite differences of discrete data (FINITE DIFFERENCE, e.g., gradient functions in MATLAB) to compute spatial gradients of phase. This method uses only two adjacent pixels for computation and is extremely sensitive to Phase Noise (Phase Noise). 2. Post-processing smoothing has the disadvantage that prior art techniques typically do a large window median filter or gaussian smoothing after the velocity map is calculated in order to reduce noise. Although the mode of 'computing before smoothing' reduces noise, the edge details of the focus are seriously blurred, and the spatial resolution is reduced. The limitations of the TPM Method are that the existing tangential plane Method (TANGENT PLANE Method, TPM) is mainly applied to Time-of-arrival (Time-Flight) surface fitting in the Time domain. Although the noise immunity is good, the direct processing in the time domain is easy to be interfered by waveform distortion and multipath reflection, and the calculated amount is large. Therefore, there is a need for an ultrasound elastography method that can effectively suppress random noise during the phase gradient computation phase while preserving the fine edge structure of tissue. Disclosure of Invention The embodiment of the specification provides an ultrasonic elastography system and method based on a local least square fitting operator, which can effectively inhibit random noise in a phase gradient calculation stage and retain a tissue fine edge structure. The technical scheme is as follows: In a first aspect, embodiments of the present disclosure provide an ultrasound elastography system based on a local least squares fitting operator, comprising: the first acquisition module acquires the space-time data of ultrasonic shear wave propagation and acquires a complex wave field under the target frequency based on the space-time data of ultrasonic shear wave propagation; The first matrix generation module is preset as follows Fitting matrix of (a)And based on a fitting matrixAcquiring a relative coordinate matrix,Representing the number of rows of the matrix,Representing the number of columns of the matrix,,To traverse the array elements of the fitting matrix row by row from left to right, the traversed firstRelative position coordinates corresponding to each array element, ifThe array of each array element is positioned at the left side of the array of the fitting matrix center array elementIs thatIf at firstThe array of each array element is positioned at the right side of the array of the central array element of the fitting matrixIs that,Represent the firstArray elements and fitting matrix the number of spaced rows of the central array element,Represents the lateral resolution, ifThe array elements are arranged on the upper side of the array elements in the center of the fitting matrixIs thatIf at firstThe array elements are arranged at the lower side of the array elements in the center of the fitting matrixIs that,Represent the firstThe number of interval rows between each array element and the array element in the center of the fitting matrix,The longitudinal resolution is indicated as such,Representing fitting matricesThe total number of array elements in the matrix; The second matrix generation module is based on a relative coordinate matrix Obtaining a fitting operator matrix according to a least square principle; A data block acquisition module for extracting, for each pixel of the complex wavefield, a pixel centered on the pixel and of a size Is a local complex data block; the vector acquisition module acquires relative phase vectors corresponding to the local complex data blocks ,Represent the firstThe relative phase vectors corresponding to the partial complex data blocks,Represent the firstThe first of the partial complex data blocksLocal pixel and the firstThe relative phase difference between the center pixels in the local complex data blocks,Representing a transpose; The component acquisition module is used for acquiring fitting wave number components corresponding to the local complex data blocks based on the fitting operator matrix and the relative phase vectors corresponding to the local complex data blocks; The image acquisition mo