WO2022141052A1 - 剪切波弹性成像方法及系统 - Google Patents

剪切波弹性成像方法及系统 Download PDF

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WO2022141052A1
WO2022141052A1 PCT/CN2020/140837 CN2020140837W WO2022141052A1 WO 2022141052 A1 WO2022141052 A1 WO 2022141052A1 CN 2020140837 W CN2020140837 W CN 2020140837W WO 2022141052 A1 WO2022141052 A1 WO 2022141052A1
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sound pressure
array element
shear wave
intensity
matrix
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PCT/CN2020/140837
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English (en)
French (fr)
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王鋐
陈建军
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无锡祥生医疗科技股份有限公司
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Priority to PCT/CN2020/140837 priority Critical patent/WO2022141052A1/zh
Publication of WO2022141052A1 publication Critical patent/WO2022141052A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings

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  • the invention relates to the technical field of ultrasonic scanning, in particular to a shear wave elasticity imaging method and system.
  • shear wave elastography can significantly shorten liver biopsies for liver fibrosis in patients with chronic hepatitis.
  • the shear wave elastography technique used to assess liver elasticity is based on shear waves generated by an internal mechanical push that is generated by the ultrasound system and directly into the liver.
  • the pulse length usually takes 100 ⁇ s in duration to generate a shear wave in the tissue as shown in Figure 1.
  • Shear wave is a mechanical wave that can be transmitted from the focal point Propagated in the lateral direction.
  • a focal point can only cover an area of a certain width, say about a centimeter; if the ROI (region of interest) is a few centimeters wide, the focal point will be repeatedly generated to bring the focal point into focus
  • each location has tracking data acquisition, so in order to generate shear wave elastography, it is usually necessary to sequentially generate multiple monofocal points at different times in the ROI to cover the entire lateral area.
  • Another approach is to perform a fast tracking data acquisition by generating multiple foci simultaneously. This approach will help reduce motion problems that can arise from a series of single foci.
  • Figure 2 shows that three focal points are generated by dividing the entire aperture into three sub-apertures, each sub-aperture is responsible for one focal point, because the 3 sub-apertures will interfere with each other, so even if each sub-aperture is concentrated at one focal point, The final focus intensity at these three positions may vary
  • Figure 3 shows the simulation results of the final intensity distribution at the three focus positions when the 64 channels are divided into three sets of sub-apertures, at positions -9mm, 0mm, 9mm
  • the three focal points at , their depth z is equal to 15mm, it can be clearly seen that the focal point in the center is almost twice as large as the two focal points on the sides, even though the emission sub-aperture, i.e. the same number of effective elements per individual focal point
  • the technical problem to be solved by the present invention is to overcome the problem of uneven intensity distribution at multiple focal positions generated by the ultrasonic probe during shear wave elastography in the prior art, thereby providing a shear wave elastography method and method. system.
  • the present invention provides the following technical solutions:
  • an embodiment of the present invention provides a shear wave elastography method, including the following steps:
  • the ultrasonic probe is controlled to perform shear wave elasticity imaging according to the intensity q of each array element.
  • the intensity of each array element is obtained according to the sound pressure component p at each focus position, the sound pressure h generated by each array element at each focus position, and the sound pressure weight w q steps, including:
  • the sound pressure weight w is updated, and the source intensity q is updated using the updated sound pressure weight w until the preset condition is met.
  • the preset condition includes: the standard deviation value of the source intensity matrix Q is less than a preset threshold;
  • the sound pressure component p at each focus position is obtained by the following formula:
  • ⁇ 0 is the density of the tissue
  • c is the speed of sound in the tissue
  • k is the wave number
  • ⁇ is the wavelength
  • q n is the source intensity of the array element n
  • L is the width of the array element
  • r is the distance from the center of the array element to the field point
  • ⁇ mn is the angle from the array element n to the field point m
  • p m is the sound pressure of the mth ultrasound focus, including amplitude and phase.
  • the sound pressure h generated by each array element at each focus position with unit sound intensity is obtained by the following formula:
  • hmn is the sound pressure generated by the nth array element at the mth position with unit sound intensity.
  • the sound pressure weight w is represented by the following formula:
  • the standard deviation value of the source intensity matrix Q is calculated by the following formula:
  • an embodiment of the present invention provides a shear wave elastography system, including:
  • the focal sound pressure acquisition module is used to acquire the sound pressure component p of the ultrasonic wave emitted by the ultrasonic probe at each focal position, wherein the required number of focal points, focal position and sound pressure are determined according to the size of the target area of the desired shear wave elastography distribution, the focus includes at least two;
  • an array element sound pressure acquisition module for acquiring the sound pressure h generated by each array element in the ultrasonic probe at each focus position
  • the sound pressure weight acquisition module is used to obtain the sound pressure weight w;
  • the intensity acquisition module of the array element is used to obtain the sound pressure component p of each array element according to the sound pressure component p at each focus position, the sound pressure h generated by each array element at each focus position, and the sound pressure weight w. strength q;
  • the intensity update module of the array element is used for, when the intensity q of each array element satisfies a preset condition, the ultrasonic probe transmits ultrasonic waves according to the current intensity q of each array element to perform shear wave elasticity imaging.
  • an embodiment of the present invention provides a computer-readable storage medium, where the computer-readable storage medium stores computer instructions, and the computer instructions are used to cause the computer to perform the cutting of the first aspect of the embodiment of the present invention. Wave elastography method.
  • an embodiment of the present invention provides a computer device, including: a memory and a processor, the memory and the processor are connected in communication with each other, the memory stores computer instructions, and the processor executes the The computer instructions are executed to execute the shear wave elastography method according to the first aspect of the embodiments of the present invention.
  • the sound pressure component p of the ultrasonic wave emitted by the ultrasonic probe at each focal position is first obtained, wherein the required amount of shear wave elastography is determined according to the size of the target area of the desired shear wave elastography.
  • the number of focal points, the focal point position and the sound pressure distribution, the focal points include at least two; the sound pressure h generated by each array element in the ultrasonic probe at each focal point position is obtained; the sound pressure weight w is obtained; according to each focal point position The sound pressure component p at the position, the sound pressure h generated by each array element at each focus position, and the sound pressure weight w, to obtain the intensity q of each array element; when the intensity q of each array element satisfies the preset conditions , controlling the ultrasonic probe to perform shear wave elasticity imaging according to the intensity q of each array element, the present invention generates high quality shear wave elasticity imaging in the tissue to be measured by controlling the intensity distribution at multiple focus positions to be uniform.
  • the weighted sound pressure weight matrix W is updated, and the updated sound pressure weight matrix W is used to update the The source intensity matrix Q, until the standard deviation value of the source intensity matrix Q is smaller than the preset threshold or the iteration times is greater than the preset iteration cutoff times, the iteration is stopped, and the intensity of each array element is controlled by this iterative weighting method to be the same, so that The resulting intensity distribution at multiple focal positions is uniform.
  • Figure 1 is a schematic diagram of the shear wave elastic generation process
  • Fig. 2 is a schematic diagram of the focus force generated by the aperture segmentation method provided in the prior art
  • FIG. 3 is a schematic diagram of the focal intensity distribution generated by the aperture segmentation method
  • FIG. 4 is a flowchart of an example of a shear wave elastography method provided in an embodiment of the present invention.
  • Fig. 5 is a coordinate diagram of the sound pressure amplitude of an array element in the far field
  • FIG. 6 is an iterative flowchart of an iterative weighting processing method provided by an embodiment of the present invention.
  • FIG. 7 is a schematic diagram of a focus intensity distribution obtained by an iterative weighting processing method according to an embodiment of the present invention.
  • FIG. 8 is a block diagram of a specific example of a shear wave elastography system provided in an embodiment of the present invention.
  • FIG. 9 is a composition diagram of a specific example of a computer device provided by an embodiment of the present invention.
  • the ultrasonic waves emitted by the ultrasonic probe array of the ultrasonic device can generate a single driving force concentrated in different positions, and can generate multiple driving forces at the same time, that is, one focus or multiple focus points.
  • the embodiments of the present invention are mainly aimed at is the case when multiple focal points are generated, a shear wave elastography method is provided, as shown in Figure 4, the method includes the following steps:
  • Step S1 Acquire the sound pressure component p of the ultrasonic wave emitted by the ultrasonic probe at each focus position, wherein the required number of focus points, focus position and sound pressure distribution are determined according to the size of the target area of the desired shear wave elasticity imaging. Include at least two.
  • the desired size of the target area for shear wave elastography is used to determine the number of focal points, focal point positions and sound pressure distribution required by ultrasound equipment. Due to the limited scanning range of a single focal point, it is usually necessary to generate multiple focal points at the same time. And do a fast track of the data.
  • the desired shear wave elastography is two-dimensional shear wave elastography, which acquires M (M not less than 2) focus points generated simultaneously by N array elements in the ultrasonic probe array of the ultrasonic elasticity testing device.
  • the sound pressure component p of the ultrasonic wave emitted by the ultrasonic probe at each focus position is obtained.
  • ⁇ 0 is the density of the tissue
  • c is the speed of sound in the tissue
  • k is the wave number
  • q is the source intensity of the array element
  • L is the width of the array element
  • ⁇ is the angular frequency
  • r is the distance from the center of the array element to the field point (measured). The distance from the location point in the tissue), ⁇ is the angle from the array element to the field point.
  • ⁇ 0 is the density of the tissue
  • c is the speed of sound in the tissue
  • k is the wave number
  • ⁇ is the wavelength
  • q n is the source intensity of the array element n ⁇ (1,N)
  • L is the width of the array element
  • r is the The distance from the element center to the field point
  • ⁇ mn is the angle from the array element n to the field point
  • p m is the sound pressure of the mth focal point of the ultrasound, including amplitude and phase.
  • the first sound pressure matrix P composed of each focal sound pressure component p is expressed as:
  • Step S2 Acquire the sound pressure H generated by each array element in the ultrasonic probe at each focus position.
  • the sound pressure h generated by the nth array element at the mth focus is calculated by the following formula, and obtained by the following formula:
  • the second sound pressure matrix H composed of the sound pressure h generated by each array element at each focus position is expressed as:
  • Step S3 Obtain the sound pressure weight w.
  • the sound pressure weight matrix W composed of each sound pressure weight w.
  • Step S4 Obtain the intensity q of each array element according to the sound pressure component p at each focus position, the sound pressure h generated by each array element at each focus position, and the sound pressure weight w.
  • the source intensity matrix Q is obtained, specifically obtained by the following formula:
  • Step S5 when the intensity q of each array element satisfies the preset condition, control the ultrasonic probe to perform shear wave elasticity imaging according to the intensity q of each array element.
  • the iterative stop condition of the present invention includes: when the standard deviation value of the source intensity matrix Q is greater than a preset threshold, updating the weighted sound pressure weight matrix W, and using the updated sound pressure weight matrix W to update the source intensity matrix Q, until When the standard deviation value of the source intensity matrix Q is less than the preset threshold ⁇ or the number of iterations is greater than the preset iteration cutoff number V, the iteration is stopped, and the entire iterative process is shown in FIG. 6 . where the standard deviation value of the source intensity matrix Q is calculated by the following formula:
  • the element in the final source intensity matrix Q is the source intensity value of each array element, and each array element is controlled to transmit signals according to the final value determined by the final source intensity matrix Q, and the phase is transmitted according to the calculated phase.
  • An embodiment of the present invention provides a shear wave elastography system, as shown in FIG. 8 , including:
  • the focal sound pressure acquisition module 1 is used to acquire the sound pressure component p of the ultrasonic wave emitted by the ultrasonic probe at each focal position, wherein the required focal number, focal position and sound are determined according to the size of the target area of the desired shear wave elastography. pressure distribution, the focus includes at least two; this module executes the method described in step S1 in Embodiment 1, and details are not repeated here.
  • the array element sound pressure acquisition module 2 is used to acquire the sound pressure h generated by each array element in the ultrasonic probe at each focus position; this module executes the method described in step S2 in Embodiment 1, and is not described here. Repeat.
  • the sound pressure weight obtaining module 3 is used to obtain the sound pressure weight w; the module executes the method described in step S3 in the embodiment 1, and details are not repeated here.
  • the intensity acquisition module 4 of the array element is used to obtain each array element according to the sound pressure component p at each focus position, the sound pressure h generated by each array element at each focus position, and the sound pressure weight w strength q; this module executes the method described in step S4 in Embodiment 1, and details are not repeated here.
  • the intensity q updating module 5 of the array elements is used for, when the intensity q of each array element satisfies the preset condition, the ultrasonic probe transmits ultrasonic waves according to the current intensity q of each array element to perform shear wave elastography.
  • This module executes the method described in step S5 in Embodiment 1, and details are not repeated here.
  • the source intensity matrix when the preset iterative stop condition is reached is used as the final source intensity to transmit an ultrasonic signal, so as to make the sound pressure intensity of multiple focal points. Evenly distributed, the ultrasonic probe array emits ultrasonic waves in the tissue to be tested according to the final array element strength to generate high-quality shear wave elastography.
  • FIG. 9 An embodiment of the present invention provides a computer device. As shown in FIG. 9 , the device may include a processor 51 and a memory 52, where the processor 51 and the memory 52 may be connected through a bus or in other ways. FIG. 9 takes the connection through a bus as an example .
  • the memory 52 can be used to store non-transitory software programs, non-transitory computer-executable programs and modules, such as corresponding program instructions/modules in the embodiments of the present invention.
  • the processor 51 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions and modules stored in the memory 52, ie, implements the shear wave elastography method in the above method embodiment 1.
  • the memory 52 may include a storage program area and a storage data area, wherein the storage program area may store an operating system and an application program required by at least one function; the storage data area may store data created by the processor 51 and the like. Additionally, memory 52 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 52 may optionally include memory located remotely from processor 51, which may be connected to processor 51 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, intranets, mobile communication networks, and combinations thereof.
  • One or more modules are stored in the memory 52, and when executed by the processor 51, execute the shear wave elastography method in Embodiment 1.
  • the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a flash memory (Flash Memory), a hard disk (Hard Disk Drive) , abbreviation: HDD) or solid-state drive (Solid-State Drive, SSD), etc.; the storage medium may also include a combination of the above-mentioned types of memories.

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Abstract

一种剪切波弹性成像方法及系统，其中剪切波弹性成像方法包括：获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，焦点包括至少两个(S1)；获取超声探头中的每个阵元在各个焦点位置处产生的声压h(S2)；获取声压权重w(S3)；根据各个焦点位置处的声压分量p、每个阵元在各个焦点位置产生的声压h以及声压权重w，获取各个阵元的强度q(S4)；当各个阵元的强度q满足预设条件时，控制超声探头按照各个阵元的强度q进行剪切波弹性成像(S5)。通过控制多个焦点处的超声强度分布均匀，在待测组织中生成质量好的剪切波弹性成像。

Description

剪切波弹性成像方法及系统 技术领域
本发明涉及超声扫查技术领域，具体涉及一种剪切波弹性成像方法及系统。
背景技术
最近的研究表明，剪切波弹性成像可以显著缩短进行慢性肝炎患者肝纤维化的肝活检，用于评估肝脏弹性的剪切波弹性成像技术基于内部机械推动产生的剪切波，这种内部推动是由超声系统所产生，并直接进入肝脏的发射波束，其脉冲长度通常需要100μs的持续时间才能在组织中产生如图1所示的剪切波，剪切波是一种机械波，可以从焦点沿横向方向传播产生。
由于剪切波在沿横向传播时会衰减，因此一个焦点只能覆盖一定宽度的区域，例如大约一厘米；如果ROI(目标区域)的宽度为几厘米宽，则将重复生成焦点以将焦点集中在ROI中的多个位置，每个位置都具有跟踪数据采集，因此为了生成剪切波弹性成像，通常需要在ROI中不同时间上依次生成多个单焦点，以覆盖整个横向区域。另一种方法是通过同时产生多个焦点而进行一次快速跟踪数据采集这种方法，将有助于减少由于一系列单焦点而可能产生的运动问题。
然而由于声场干扰用梳状焦点法产生的多个焦点可能并不相似，现有技术采用孔径分割方法，产生超声波来克服这种焦点强度不均匀的分布，也无法达到良好的效果。例如，图2显示了通过将整个孔径分为三个子孔径来产生三个焦点，每个子孔负责一个焦点，因为3个子孔径之间会相互干扰，因此即使每个子孔径都集中在一个焦点位置，这三个位置的最终焦点强度可能会有所不同，图3示出了将64个通道分成三组子孔径时在三个焦点位置的最终强度分布的模拟结果，在位置-9mm，0mm，9mm处的三个焦点，它们的深度z等于15mm，可以清楚地看到，中央的焦点几乎是两侧的两个焦点的两倍，即使发射子孔径，即每个单独焦点的有效阵元数量相同，产生的最终焦点的强度通常也不相同。
发明内容
因此，本发明要解决的技术问题在于克服现有技术中在剪切波弹性成像时，超声探头产生多个焦点位置处的强度分布不均的问题，从而提供一种剪切波弹性成像方法及系统。
为达到上述目的，本发明提供如下技术方案：
第一方面，本发明实施例提供一种剪切波弹性成像方法，包括如下步骤：
获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，所述焦点包括至少两个；
获取所述超声探头中的每个阵元在各个焦点位置处产生的声压h；
获取声压权重w；
根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q；
当各个阵元的强度q满足预设条件时，控制所述超声探头按照所述各个阵元的强度q进行剪切波弹性成像。
在一实施例中，所述根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q的步骤，包括：
构建由各个焦点位置处的声压分量p组成的第一声压矩阵P、每个阵元在各个焦点位置处产生的声压h组成的第二声压矩阵H，以及由各个声压权重w组成的声压权重矩阵W，则由各个阵元的强度q组成的源强度矩阵Q通过以下公式获取：
Q＝WH *T(HWH *T) -1P。
在一实施例中，当源强度q满足不满足预设条件时，更新声压权重w，利用更新后的声压权重w更新所述源强度q，直至满足所述预设条件。
在一实施例中，所述预设条件包括：源强度矩阵Q的标准偏差值小于预设阈值；
当源强度矩阵Q的标准偏差值大于预设阈值时，更新权重声压权重矩阵W，利用更新后的声压权重矩阵W更新所述源强度矩阵Q，直至当源强度矩阵Q的标准偏差值小于预设阈值或迭代次数大于预设迭代截止次数值时，停止迭代。
在一实施例中，各个焦点位置处的声压分量p，通过以下公式获取：
Figure PCTCN2020140837-appb-000001
其中，
Figure PCTCN2020140837-appb-000002
ρ 0是组织的密度，c是组织中声音的速度，k是波数，λ是波长，q n是阵元n的源强度，L是阵元的宽度，r是从阵元中心到场点的距离，θ mn是从阵元n到场点m的角度，p m是超声第m个焦点的声压，包括幅度和相位。
在一实施例中，每个阵元以单位声强度在各个焦点位置产生的声压h，通过以下公式获取：
Figure PCTCN2020140837-appb-000003
其中，h mn是第n个阵元以单位声强度在第m个位置产生的声压。
在一实施例中，所述声压权重w，通过以下公式表示：
Figure PCTCN2020140837-appb-000004
其中，v是迭代次数，N是阵元的数量。
在一实施例中，所述源强度矩阵Q的标准偏差值通过以下公式计算：
Figure PCTCN2020140837-appb-000005
Figure PCTCN2020140837-appb-000006
第二方面，本发明实施例提供一种剪切波弹性成像系统，包括：
焦点声压获取模块，用于获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，所述焦点包括至少两个；
阵元声压获取模块，用于获取所述超声探头中的每个阵元在各个焦点位置处产生的声压h；
声压权重获取模块，用于获取声压权重w；
阵元的强度获取模块，用于根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q；
阵元的强度更新模块，用于当个阵元的强度q满足预设条件时，所述超声探头按照当前的各个阵元的强度q发射超声波进行剪切波弹性成像。
第三方面，本发明实施例提供一种计算机可读存储介质，所述计算机可读存储介质存储有计算机指令，所述计算机指令用于使所述计算机执行本发明实施例第一方面的剪切波弹性成像方法。
第四方面，本发明实施例提供一种计算机设备，包括：存储器和处理器，所述存储器和所述处理器之间互相通信连接，所述存储器存储有计算机指令，所述处理器通过执行所述计算机指令，从而执行本发明实施例第一方面的剪切波弹性成像方法。
本发明技术方案，具有如下优点：
1、本发明提供的剪切波弹性成像方法及系统，首先获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，所述焦点包括至少两个；获取所述超声探头中的每个阵元在各个焦点位置处产生的声压h；获取声压权重w；根据各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q；当各个阵元的强度q满足预设条件时，控制所述超声探头按照各个阵元的强度q进行剪切波弹性成像，本发明通过控制多个焦点位置处的强度分布均匀，在待测组织中生成质量好的剪切波弹性成像。
2.本发明提供的剪切波弹性成像方法及系统，当源强度矩阵Q的标准偏差值大于预设阈值时，更新权重声压权重矩阵W，利用更新后的声压权重矩阵W更新所述源强度矩阵Q，直至当源强度矩阵Q的标准偏差值小于预设阈值或迭代次数大于预设迭代截止次数值时停止迭代，通过这种迭代加权的方式控制每个阵元的强度相同，使得最终生成的多个焦点位置处的强度分布均匀。
附图说明
为了更清楚地说明本发明具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为剪切波弹性生成过程的示意图；
图2为现有技术中提供的采用孔径分割方法产生的焦点力示意图；
图3为采用孔径分割方法产生的焦点强度分布示意图；
图4为本发明实施例中提供的剪切波弹性成像方法的一个示例的流程图；
图5为一个阵元在远场中的声压幅度的坐标图；
图6为本发明实施例提供的迭代加权处理方式的迭代流程图；
图7为本发明实施例提供的通过迭代加权处理方式得到的焦点强度分布示意图；
图8为本发明实施例中提供的剪切波弹性成像系统的一个具体示例的模块组成图；
图9为本发明实施例提供的计算机设备一个具体示例的组成图。
具体实施方式
下面将结合附图对本发明的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
此外，下面所描述的本发明不同实施方式中所涉及的技术特征只要彼此之间未构成冲突就可以相互结合。
实施例1
声波在组织中的传播比剪切波传播的快得多(约1000倍)，因此可以完全跟踪剪切波在组织中沿横向方向的传播，通过测量感兴趣区域的剪切波速度，可以提供组织的二维定量弹性图。为此需要非常高的运动检测帧频率，因为剪切波速度通常约为每秒几米， 为了获得剪切波弹性成像，超声系统需要将跟踪信号发送到组织并接收反向散射的回波，可以传输动态激励以在体内产生剪切波，检测剪切波传播速度的方法是使用相同的成像换能器将跟踪脉冲重复发送到人体，并接收反射信号以监视组织位移。
在实际应用中，超声设备的超声探头阵列发射的超声波可以产生聚集于不同位置的单个推动力，可以同时产生多个推动力，即会产生一个焦点或多个焦点，本发明实施例主要针对的是产生多个焦点时的情况，提供一种剪切波弹性成像方法，如图4所示，该方法包括如下步骤：
步骤S1：获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，所述焦点包括至少两个。
实际应用中根据期望剪切波弹性成像的目标区域大小，并以此来确定超声设备所需的焦点数、焦点位置和声压分布，由于单个焦点的扫描范围有限，通常需要同时产生多个焦点而进行一次快速跟踪数据。
在一具体实施例中，期望的剪切波弹性成像为二维剪切波弹性成像，获取超声弹性检测设备的超声探头阵列中N个阵元同时参与产生的M(M不小于2)个焦点的声压，获取超声探头发射的超声波在各个焦点位置处的声压分量p。
超声探头阵列中一个阵元在远场中的声压幅度如图5所示，声压幅度通过以下公式表示：
Figure PCTCN2020140837-appb-000007
其中，
Figure PCTCN2020140837-appb-000008
ρ 0是组织的密度，c是组织中声音的速度，k是波数，q是阵元的源强度，L是阵元的宽度，ω是角频率，r是从阵元中心到场点(被测组织中的位置点)的距离，θ是从阵元到场点的角度。
假设有N个阵元同时参与产生M焦点，通常N>>M，对于第m∈(1,M)个焦点的声压通过p m以下公式表示：
Figure PCTCN2020140837-appb-000009
其中，
Figure PCTCN2020140837-appb-000010
ρ 0是组织的密度，c是组织中声音的速度，k是波数，λ是波长，q n是阵元n∈(1,N)的源强度，L是阵元的宽度，r是从阵元中心到场点的距离，θ mn是从阵元n到场点的角度，p m是超声第m个焦点的声压，包括幅度和相位。
因此，由各个焦点声压分量p组成的第一声压矩阵P表示为：
Figure PCTCN2020140837-appb-000011
步骤S2：获取所述超声探头中的每个阵元在各个焦点位置处产生的声压H。
本发明实施例中，第n个阵元在第m个焦点产生的声压h，通过以下公式计算，通过以下公式获取：
Figure PCTCN2020140837-appb-000012
由每个阵元在各个焦点位置处产生的声压h组成的第二声压矩阵H表示为：
Figure PCTCN2020140837-appb-000013
步骤S3：获取声压权重w。
本发明实施例中的声压权重w，通过以下公式表示：
Figure PCTCN2020140837-appb-000014
由各个声压权重w组成的声压权重矩阵W。
步骤S4：根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q。
构建由每个阵元的声强度q构成的源强度矩阵Q：
Figure PCTCN2020140837-appb-000015
通过第一声压矩阵P、第二声压矩阵H以及声压权重矩阵W，获取源强度矩阵Q，具 体通过以下公式获得：
Q＝WH *T(HWH *T) -1P    (8)
步骤S5：当各个阵元的强度q满足预设条件时，控制所述超声探头按照所述各个阵元的强度q进行剪切波弹性成像。
由于计算出的源强度矩阵Q可能对每个阵元都不具有相同的强度，因此本发明实施例通过迭代加权的处理方式以使阵元的强度均匀分布。本发明的迭代停止条件，包括：当源强度矩阵Q的标准偏差值大于预设阈值时，更新权重声压权重矩阵W，利用更新后的声压权重矩阵W更新所述源强度矩阵Q，直至当源强度矩阵Q的标准偏差值小于预设阈值σ或迭代次数大于预设迭代截止次数值V时，停止迭代，整个迭代流程如图6所示。其中源强度矩阵Q的标准偏差值，通过以下公式计算：
Figure PCTCN2020140837-appb-000016
Figure PCTCN2020140837-appb-000017
在一具体实施例中，在迭代之前设置初始的第一声压矩阵P和初始的声压权重矩阵W均为单位矩阵，即W＝I，P＝[1….1] T，仅作为举例，不以此为限，在实际应用中根据具体需求做合理设置初始值。在迭代停止之后得到最终源强度矩阵Q中的元素为每个阵元的源强度值，控制每个阵元按照最终源强度矩阵Q确定的最终值发射信号，相位按照计算得到的相位发射。
基于图3中示例相同的超声系统设备配置，采用的本发明实施提供的方法后，如图7所示，在三个焦点位置的最终强度分布的模拟结果，可以清楚地看到，在中间焦点位置处的强度与在其他两个焦点位置处的强度非常相似，达到了焦点强度均匀分布的效果，从而使得最终的生成剪切波弹性成像质量更好。
实施例2
本发明实施例提供一种剪切波弹性成像系统，如图8所示，包括：
焦点声压获取模块1，用于获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，所述焦点包括至少两个；此模块执行实施例1中的步骤S1所描述的方法， 在此不再赘述。
阵元声压获取模块2，用于获取所述超声探头中的每个阵元在各个焦点位置处产生的声压h；此模块执行实施例1中的步骤S2所描述的方法，在此不再赘述。
声压权重获取模块3，用于获取声压权重w；模块执行实施例1中的步骤S3所描述的方法，在此不再赘述。
阵元的强度获取模块4，用于根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q；此模块执行实施例1中的步骤S4所描述的方法，在此不再赘述。
阵元的强度q更新模块5，用于当个阵元的强度q满足预设条件时，所述超声探头按照当前的各个阵元的强度q发射超声波进行剪切波弹性成像。此模块执行实施例1中的步骤S5所描述的方法，在此不再赘述。
本发明实施例提供的剪切波弹性成像系统，通过迭代加权的处理方式，将达到预设迭代停止条件时的源强度矩阵，作为最终源强度发射超声信号，进行使得多个焦点的声压强度分布均匀，超声探头阵列根据最终阵元强度，在待测组织中发出超声波生成质量好的剪切波弹性成像。
实施例3
本发明实施例提供一种计算机设备，如图9所示，该设备可以包括处理器51和存储器52，其中处理器51和存储器52可以通过总线或者其他方式连接，图9以通过总线连接为例。
存储器52作为一种非暂态计算机可读存储介质，可用于存储非暂态软件程序、非暂态计算机可执行程序以及模块，如本发明实施例中的对应的程序指令/模块。处理器51通过运行存储在存储器52中的非暂态软件程序、指令以及模块，从而执行处理器的各种功能应用以及数据处理，即实现上述方法实施例1中的剪切波弹性成像方法。
存储器52可以包括存储程序区和存储数据区，其中，存储程序区可存储操作系统、至少一个功能所需要的应用程序；存储数据区可存储处理器51所创建的数据等。此外，存储器52可以包括高速随机存取存储器，还可以包括非暂态存储器，例如至少一个磁盘存储器件、闪存器件、或其他非暂态固态存储器件。在一些实施例中，存储器52可选包括相对于处理器51远程设置的存储器，这些远程存储器可以通过网络连接至处理器51。上述网络的实例包括但不限于互联网、企业内部网、企业内网、移动通信网及其 组合。
一个或者多个模块存储在存储器52中，当被处理器51执行时，执行实施例1中的剪切波弹性成像方法。
上述计算机设备具体细节可以对应参阅实施例1中对应的相关描述和效果进行理解，此处不再赘述。
本领域技术人员可以理解，实现上述实施例方法中的全部或部分流程，是可以通过计算机程序来指令相关的硬件来完成的程序可存储于一计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，存储介质可为磁碟、光盘、只读存储记忆体(Read-Only Memory，ROM)、随机存储记忆体(Random Access Memory，RAM)、快闪存储器(Flash Memory)、硬盘(Hard Disk Drive，缩写：HDD)或固态硬盘(Solid-State Drive，SSD)等；存储介质还可以包括上述种类的存储器的组合。
显然，上述实施例仅仅是为清楚地说明所作的举例，而并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引申出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (11)

  1. 一种剪切波弹性成像方法，其特征在于，包括如下步骤：
    获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，所述焦点包括至少两个；
    获取所述超声探头中的每个阵元在各个焦点位置处产生的声压h；
    获取声压权重w；
    根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q；
    当各个阵元的强度q满足预设条件时，控制所述超声探头按照所述各个阵元的强度q进行剪切波弹性成像。
  2. 根据权利要求1所述的剪切波弹性成像方法，其特征在于，所述根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q的步骤，包括：
    构建由各个焦点位置处的声压分量p组成的第一声压矩阵P、每个阵元在各个焦点位置处产生的声压h组成的第二声压矩阵H，以及由各个声压权重w组成的声压权重矩阵W，则由各个阵元的强度q组成的源强度矩阵Q通过以下公式获取：
    Q＝WH *T(HWH *T) -1P。
  3. 根据权利要求2所述的剪切波弹性成像方法，其特征在于，当源强度q满足不满足预设条件时，更新声压权重w，利用更新后的声压权重w更新所述源强度q，直至满足所述预设条件。
  4. 根据权利要求3所述的剪切波弹性成像方法，其特征在于，所述预设条件包括：源强度矩阵Q的标准偏差值小于预设阈值；
    当源强度矩阵Q的标准偏差值大于预设阈值时，更新权重声压权重矩阵W，利用更新后的声压权重矩阵W更新所述源强度矩阵Q，直至当源强度矩阵Q的标准偏差值小于预设阈值或迭代次数大于预设迭代截止次数值时，停止迭代。
  5. 根据权利要求1所述的剪切波弹性成像方法，其特征在于，各个焦点位置处的声压分量p，通过以下公式获取：
    Figure PCTCN2020140837-appb-100001
    其中，
    Figure PCTCN2020140837-appb-100002
    ρ 0是组织的密度，c是组织中声音的速度，k是波数，λ是波长，q n是阵元n的源强度，L是阵元的宽度，r是从阵元中心到场点的距离，θ mn是从阵元n到场点m的角度，p m是超声第m个焦点的声压，包括幅度和相位。
  6. 根据权利要求5所述的剪切波弹性成像方法，其特征在于，每个阵元以单位声强度在各个焦点位置产生的声压h，通过以下公式获取：
    Figure PCTCN2020140837-appb-100003
    其中，h mn是第n个阵元以单位声强度在第m个位置产生的声压。
  7. 根据权利要求5所述的剪切波弹性成像方法，其特征在于，所述声压权重w，通过以下公式表示：
    Figure PCTCN2020140837-appb-100004
    其中，v是迭代次数，N是阵元的数量。
  8. 根据权利要求4所述的剪切波弹性成像方法，其特征在于，所述源强度矩阵Q的标准偏差值通过以下公式计算：
    Figure PCTCN2020140837-appb-100005
    Figure PCTCN2020140837-appb-100006
  9. 一种剪切波弹性成像系统，其特征在于，包括：
    焦点声压获取模块，用于获取超声探头发射的超声波在各个焦点位置处的声压分量p，其中根据期望剪切波弹性成像的目标区域大小来决定所需要的焦点数、焦点位置和声压分布，所述焦点包括至少两个；
    阵元声压获取模块，用于获取所述超声探头中的每个阵元在各个焦点位置处产生的声压h；
    声压权重获取模块，用于获取声压权重w；
    阵元的强度获取模块，用于根据所述各个焦点位置处的声压分量p、所述每个阵元在各个焦点位置产生的声压h及所述声压权重w，获取各个阵元的强度q；
    阵元的强度更新模块，用于当个阵元的强度q满足预设条件时，所述超声探头按照当前的各个阵元的强度q发射超声波进行剪切波弹性成像。
  10. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储有计算机指令，所述计算机指令用于使所述计算机执行如权利要求1-8任一项所述的剪切波弹性成像方法。
  11. 一种计算机设备，其特征在于，包括：存储器和处理器，所述存储器和所述处理器之间互相通信连接，所述存储器存储有计算机指令，所述处理器通过执行所述计算机指令，从而执行如权利要求1-8任一项所述的剪切波弹性成像方法。
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