Viscoelasticity measurement method and ultrasonic measurement system

Abstract

A viscoelasticity measurement method (100, 700) and an ultrasonic measurement system (1000), the viscoelasticity measurement method (100, 700) comprising: emitting an acoustic radiation force pulse to a measured object to generate a shear wave in a region of interest of the measured object (S110); transmitting a first ultrasonic wave tracking a shear wave to the region of interest, and receiving a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data (S120); obtaining a shear wave signal of the region of interest according to the first ultrasonic echo data (S130); extracting shear wave components of at least two different frequencies from the shear wave signal (S140); determining the phase velocities of the shear waves according to the shear wave components of at least two different frequencies (S150); determining viscosity information reflecting the viscosity of the region of interest according to the at least two phase velocities (S160); and outputting the viscosity information (S170). And the viscosity information of the region of interest can be determined by carrying out one-time viscoelasticity measurement.

Description

[0001] This application is a divisional application of the invention patent application with application number 202080053473.1, application date April 24, 2020, and name “Viscoelasticity measurement method and ultrasonic measurement system”. Technical Field

[0002] The present application relates to the field of ultrasonic measurement technology, and more specifically to a viscoelasticity measurement method and an ultrasonic measurement system. Background Art

[0003] Ultrasonic elastography technology extracts information related to the hardness of tissues for imaging. It is related to the non-invasive auxiliary diagnosis of major diseases such as breast cancer and cirrhosis, and has been a research hotspot in the field of ultrasound imaging in the past two decades. After years of development, ultrasound elastography technology has gradually matured. In recent years, it has been more widely used in clinical research and auxiliary diagnosis of various parts of the human body, such as the liver, breast, thyroid, musculoskeletal, blood vessels, prostate, cervix, etc. Ultrasonic elastography technology can qualitatively reflect the difference in hardness of the lesion relative to the surrounding tissue, or quantitatively reflect the hardness-related physical parameters of the target tissue, such as Young's modulus, shear modulus, etc., and is widely welcomed by doctors.

[0004] Commonly used ultrasound elastic imaging techniques include strain elastic imaging, shear wave elastic imaging, and transient elastic imaging. Among them, shear wave elastic imaging technology generates shear wave propagation by emitting special pulses into the tissue to form acoustic radiation force, and then detects and records the propagation process of shear waves through ultrasonic waves, and further calculates the propagation speed of shear waves, and finally obtains elastic modulus parameters reflecting tissue hardness, realizing quantitative elastic imaging. This technology has greatly expanded the clinical application field of elastic imaging and aroused great research interest.

[0005] In most current elasticity-related studies, tissues are considered pure elastic bodies, and elastic imaging technology is mainly based on the assumption of pure elastic bodies for imaging. In particular, quantitative elastic imaging technology usually only calculates the elastic modulus for display. However, more and more studies have shown that in addition to elasticity, human tissues also have viscosity. Elasticity and viscosity jointly affect the propagation speed of shear waves in tissues. Although there are very few clinical studies on the correlation between tissue viscosity and disease, existing studies have shown that tissue viscosity may be related to the progression of diseases such as hepatitis. Therefore, when performing elastic imaging, if viscosity-related information can be extracted at the same time, it will have great clinical potential value. Summary of the invention

[0006] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0007] A first aspect of an embodiment of the present application provides a viscoelasticity measurement method, comprising:

[0008] transmitting an acoustic radiation force pulse to the object to be measured to generate a shear wave in a region of interest of the object to be measured;

[0009] Transmitting a first ultrasonic wave tracking the shear wave to the region of interest, and receiving a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data;

[0010] Obtaining a shear wave signal of the region of interest according to the first ultrasonic echo data;

[0011] extracting at least two shear wave components of different frequencies from the shear wave signal;

[0012] Determining the phase velocity of the shear wave according to the at least two shear wave components of different frequencies respectively;

[0013] Determining viscosity information reflecting the viscosity of the region of interest based on at least two of the phase velocities;

[0014] The stickiness information is output.

[0015] A second aspect of the embodiment of the present application provides a viscoelasticity measurement method, comprising:

[0016] Acquire shear wave signals of a region of interest of the object under test;

[0017] extracting at least two shear wave components of different frequencies from the shear wave signal;

[0018] Determining the phase velocity of the shear wave according to the at least two shear wave components of different frequencies respectively;

[0019] Viscosity information reflecting the viscosity of the region of interest is determined based on at least two of the phase velocities.

[0020] A third aspect of an embodiment of the present application provides an elasticity measurement method, the method comprising:

[0021] transmitting an acoustic radiation force pulse to the object to be measured to generate a broadband shear wave in a region of interest of the object to be measured;

[0022] Transmitting a first ultrasonic wave tracking the shear wave to the region of interest, and receiving a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data;

[0023] Obtaining a shear wave signal of the region of interest according to the first ultrasonic echo data;

[0024] Extracting a shear wave component of at least one frequency from the shear wave signal;

[0025] A phase velocity of the shear wave is determined based on the shear wave component of the at least one frequency.

[0026] A fourth aspect of the embodiments of the present application provides an elasticity measurement method, the method comprising:

[0027] Acquire shear wave signals of a region of interest of the object under test;

[0028] Extracting a shear wave component of at least one frequency from the shear wave signal;

[0029] A phase velocity of the shear wave is determined based on the shear wave component of the at least one frequency.

[0030] A fifth aspect of the embodiments of the present application provides an ultrasonic measurement system, including:

[0031] Ultrasound probe;

[0032] A transmitting / receiving circuit is used to stimulate the ultrasonic probe to transmit an acoustic radiation force pulse to the object to be measured, so as to generate a shear wave in the region of interest of the object to be measured; and to stimulate the ultrasonic probe to transmit a first ultrasonic wave tracking the shear wave to the region of interest, and to receive a first ultrasonic echo of the region of interest, so as to obtain first ultrasonic echo data;

[0033] Processor for:

[0034] Obtaining a shear wave signal of the region of interest according to the first ultrasonic echo data;

[0035] extracting at least two shear wave components of different frequencies from the shear wave signal;

[0036] Determining the phase velocity of the shear wave according to the at least two shear wave components of different frequencies respectively;

[0037] Determining viscosity information reflecting the viscosity of the region of interest based on at least two of the phase velocities;

[0038] An output device is used to output the viscosity information.

[0039] A sixth aspect of an embodiment of the present application provides an ultrasonic measurement system, the ultrasonic measurement system comprising a memory and a processor, the memory storing a computer program executed by the processor, the computer program performing the following steps when executed by the processor:

[0040] Acquire shear wave signals of a region of interest of the object under test;

[0041] extracting at least two shear wave components of different frequencies from the shear wave signal;

[0042] Determining the phase velocity of the shear wave according to the at least two shear wave components of different frequencies respectively;

[0043] Viscosity information reflecting the viscosity of the region of interest is determined based on at least two of the phase velocities.

[0044] A seventh aspect of the present application provides an ultrasonic measurement system, the ultrasonic measurement system comprising:

[0045] Ultrasound probe;

[0046] A transmitting / receiving circuit is used to stimulate the ultrasonic probe to transmit an acoustic radiation force pulse to the object to be measured, so as to generate a shear wave in the region of interest of the object to be measured; and to stimulate the ultrasonic probe to transmit a first ultrasonic wave tracking the shear wave to the region of interest, and to receive a first ultrasonic echo of the region of interest, so as to obtain first ultrasonic echo data;

[0047] Processor for:

[0048] Obtaining a shear wave signal of the region of interest according to the first ultrasonic echo data;

[0049] Extracting a shear wave component of at least one frequency from the shear wave signal;

[0050] A phase velocity of the shear wave is determined based on the shear wave component of the at least one frequency.

[0051] An eighth aspect of the embodiments of the present application provides an ultrasonic measurement system, the ultrasonic measurement system comprising a memory and a processor, the memory storing a computer program executed by the processor, and the computer program performs the following steps when executed by the processor:

[0052] Acquire shear wave signals of a region of interest of the object under test;

[0053] Extracting a shear wave component of at least one frequency from the shear wave signal;

[0054] A phase velocity of the shear wave is determined based on the shear wave component of the at least one frequency.

[0055] A ninth aspect of an embodiment of the present application provides a computer storage medium on which a computer program is stored. When the computer program is executed by a computer or a processor, the steps of the viscoelasticity measurement method or the elasticity measurement method provided in the embodiment of the present application are implemented.

[0056] According to the viscoelasticity measurement method and ultrasonic measurement system of the embodiment of the present application, shear wave components of different frequencies are extracted from the shear wave signal, and the phase velocity of each shear wave component is obtained, and information reflecting the viscosity of the tissue can be obtained with only one measurement. According to the elasticity measurement method of the embodiment of the present application, the shear wave component is extracted from the shear wave signal and its corresponding phase velocity is calculated, and the phase velocity can reflect the elastic information of the tissue. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic flow chart of a viscoelasticity measurement method according to an embodiment of the present application is shown;

[0058] Figure 2 is a spectrum diagram of a shear wave signal according to an embodiment of the present application;

[0059] Figure 3 For Figure 2 The frequency spectrum of the shear wave component separated from the shear wave signal shown;

[0060] Figure 4A shows a vibration waveform of a shear wave signal according to an embodiment of the present application;

[0061] Figure 4B , Figure 4C Shown respectively from Figure 4A The vibration waveforms of shear wave components of different frequencies extracted from the shear wave signal shown;

[0062] Figure 5A A basic ultrasound image and a region of interest determined in the basic ultrasound image according to one embodiment of the present application are shown;

[0063] Figure 5B The figure shows a basic ultrasound image and an elasticity image displayed in a superimposed manner according to an embodiment of the present application;

[0064] Figure 5C The figure shows a basic ultrasound image and a viscous image displayed in superposition according to one embodiment of the present application;

[0065] Figure 6 A basic ultrasound image and elastic coefficient and viscosity coefficient according to one embodiment of the present application are shown;

[0066] Figure 7 A schematic flow chart of a viscoelasticity measurement method according to another embodiment of the present application is shown;

[0067] Figure 8 A schematic flow chart of an elasticity measurement method according to an embodiment of the present application is shown;

[0068] Fig. 9 A schematic flow chart of an elasticity measurement method according to another embodiment of the present application is shown;

[0069] Fig.10 A schematic block diagram of an ultrasonic measurement system according to an embodiment of the present application is shown;

[0070] Fig.11 A schematic block diagram of an ultrasonic measurement system according to another embodiment of the present application is shown. DETAILED DESCRIPTION

[0071] In order to make the purpose, technical solutions and advantages of the present application more obvious, the example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0072] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0073] It should be understood that the present application can be implemented in different forms and should not be interpreted as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0074] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0075] In order to thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution proposed by the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0076] In order to thoroughly understand the present application, a detailed structure will be proposed in the following description to illustrate the technical solution proposed by the present application. The optional embodiments of the present application are described in detail as follows, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0077] The embodiment of the present application is mainly used to multiplex the ultrasonic echo data obtained in the process of shear wave elasticity measurement, separate the shear wave components of different frequencies from the shear wave signal and calculate the corresponding shear wave velocities respectively, so as to obtain viscosity information. Figure 1 Describe the viscoelasticity measurement method according to one embodiment of the present application, Figure 1 is a schematic flow chart of a viscoelasticity measurement method 100 according to an embodiment of the present application.

[0078] like Figure 1 As shown, a viscoelasticity measurement method 100 according to an embodiment of the present application includes the following steps:

[0079] In step S110, an acoustic radiation force impulse (ARFI) is emitted to the object to be measured to generate shear waves in a region of interest of the object to be measured;

[0080] In step S120, a first ultrasonic wave tracking the shear wave is transmitted to the region of interest, and a first ultrasonic echo of the region of interest is received to obtain first ultrasonic echo data;

[0081] In step S130, a shear wave signal of the region of interest is obtained according to the first ultrasonic echo data;

[0082] In step S140, at least two shear wave components of different frequencies are extracted from the shear wave signal;

[0083] In step S150, the phase velocity of the shear wave is determined according to the at least two shear wave components of different frequencies respectively;

[0084] In step S160, viscosity information reflecting the viscosity of the region of interest is determined according to at least two of the phase velocities;

[0085] In step S170, the viscosity information is output.

[0086] The viscoelasticity measurement method 100 of the embodiment of the present application adds a step of extracting shear wave components of different frequencies in the shear wave signal based on conventional shear wave elasticity measurement, and calculates the shear wave propagation speeds corresponding to the shear wave components of different frequencies, thereby obtaining viscosity information reflecting the viscosity of the tissue. According to the viscoelasticity measurement method 100 of the embodiment of the present application, the viscosity information and elasticity information of the tissue can be obtained simultaneously based on a single viscoelasticity measurement.

[0087] Generally, before executing step S110, the position of the region of interest is first determined according to a conventional ultrasound image of the object under test.

[0088] Specifically, a second ultrasonic wave can be emitted to the object under test by an ultrasonic probe, and an ultrasonic echo of the second ultrasonic wave can be received to obtain second ultrasonic echo data. Afterwards, the second ultrasonic echo data can be subjected to beam synthesis processing by a beam synthesis circuit, and then the beam synthesized second ultrasonic echo data is sent to a processor for relevant image processing to obtain a basic ultrasonic image. According to different imaging modes required by the user, the processor can process the second ultrasonic echo signal differently to obtain ultrasonic image data of different modes, and then form basic ultrasonic images of different modes through logarithmic compression, dynamic range adjustment, digital scan conversion and other processing, such as two-dimensional ultrasonic images including B images and C images. Conventional ultrasonic images can provide relevant information such as lesion morphology and blood flow distribution.

[0089] Afterwards, the position of the region of interest can be determined based on the basic ultrasound image. In one example, determining the position of the region of interest based on the conventional ultrasound image specifically includes: outputting the conventional ultrasound image, and marking the position of the region of interest on the conventional ultrasound image. For example, the basic ultrasound image can be displayed on a display, and the user manually selects the region of interest on the basic ultrasound image, and the position of the region of interest is determined based on the detected user input instruction.

[0090] In another example, the position of the region of interest can be automatically determined on the basic ultrasound image based on a relevant machine recognition algorithm. In other examples, the region of interest can also be obtained by semi-automatic detection, for example, the position of the region of interest on the basic ultrasound image is first automatically detected based on a machine recognition algorithm, and then further modified or corrected by the user to obtain a more accurate position of the region of interest.

[0091] Next, in step S110 to step S130, the acoustic radiation force focused impact can be performed according to the position of the region of interest selected in the above manner and in accordance with a pre-set pulse sequence. Specifically, the ultrasonic probe emits a special ultrasonic push pulse to the tissue of the region of interest of the object under test to generate the propagation of shear waves based on the acoustic radiation force in the tissue. The length of the ultrasonic push pulse is generally greater than 100us. Since the shear wave generated by the acoustic radiation force pulse itself has a small amplitude and the shear wave will decay rapidly as it propagates, in order to enhance the intensity and range of the generated shear wave, multiple ultrasonic push pulses are often emitted continuously.

[0092] Next, the ultrasonic probe continuously emits a series of first ultrasonic waves that track the shear wave to the tissue in the area of ​​interest for a period of time (generally tens of milliseconds), and receives its ultrasonic echo to obtain first ultrasonic echo data, and obtains a shear wave signal based on the first ultrasonic echo data. The shear wave signal is the echo signal of the shear wave, which is used to characterize the vibration state of the tissue when the shear wave propagates in the tissue. The shear wave signal obtained by the above method is a broadband signal, which includes multiple shear wave components within 0 to 1000 Hz, and each shear wave component of the shear wave signal can be regarded as a signal that characterizes the vibration state of the tissue caused by a shear wave of a certain frequency.

[0093] Specifically, the processor of the ultrasonic measurement system can calculate the vibration state of the tissue when the shear wave propagates in the tissue based on the above-mentioned first ultrasonic echo data, and the shear wave signal is a signal that characterizes the vibration state of the tissue over a period of time. According to the wave characteristics, when the shear wave propagates through a certain position in the tissue, the tissue at the corresponding position will vibrate, and when the shear wave propagates away from a certain position, the tissue at that position will return to its original state. Therefore, by making a correlation comparison between the ultrasonic echoes obtained at different times, the movement information of the tissue over a period of time can be obtained. Among them, the motion information can be the displacement of the tissue relative to a reference time, the movement speed of the tissue, the movement acceleration of the tissue, the strain of the tissue, etc., or it can be data based on the above variables that have been further processed by filtering, differentiation, integration, etc.

[0094] The correlation comparison may be a comparison calculation between ultrasonic echo signals obtained at different adjacent moments, or a comparison calculation between ultrasonic echoes at different moments and echo signals at the same reference moment. The correlation comparison algorithm may include a general algorithm for conventional tissue displacement detection, such as a cross-correlation comparison algorithm based on block matching, a calculation method based on Doppler frequency shift, a method based on phase shift detection, etc. The embodiment of the present application does not limit the specific algorithm used to detect tissue motion information.

[0095] Afterwards, the tissue movement information caused by the shear wave at different times is summarized, and the vibration waveform of the shear wave signal can be observed. Figure 4A The velocity-time curve of tissue movement at a certain position in the tissue over a period of time is shown. Of course, the vibration waveform of the shear wave signal can also be observed by summarizing other tissue movement information mentioned above over a period of time, such as by drawing a tissue displacement-time curve.

[0096] In step S140, at least two shear wave components of different frequencies are extracted from the shear wave signal. Shear wave components of different frequencies can be regarded as tissue vibration information caused by shear waves of different frequencies. By extracting shear wave components of different frequencies from the shear wave signal, only one acoustic radiation force pulse transmission and the first ultrasonic wave transmission and the first ultrasonic echo reception are required to obtain tissue vibration information caused by shear waves of different frequencies for subsequent calculation of viscosity parameters without multiple transmissions and receptions.

[0097] In one embodiment, the shear wave signal can be filtered to extract at least two shear wave components of different frequencies. It should be noted that the filtering method can be performed in the time domain, frequency domain or various algorithms, and the algorithm can also be a convolution operation, etc. Of course, the filtering process can also include a series of processing processes before or after filtering, which is not specifically limited here.

[0098] See also Figure 2 and Figure 3 , Figure 2 The spectrum diagram of the wide-band shear wave signal obtained in step S130 is shown. The shear wave signal includes multiple shear wave components within the range of 0 to 1000 Hz, so the spectrum diagram has a higher amplitude within a wider frequency band. Figure 3 The spectrum of the shear wave component with a center frequency of 300 Hz extracted from the shear wave signal is shown in FIG. Figure 3 It can be seen that the spectrum of the shear wave component has a high amplitude only around 300 Hz.

[0099] Reference Figure 4A-4C , as mentioned above, Figure 4A The waveform of the broadband shear wave signal is shown. Figure 4B For Figure 4A The waveform diagram of the shear wave component with a center frequency of 300 Hz extracted from the wide-band shear wave signal is shown. Figure 4C For Figure 4A The waveform diagram of the shear wave component with a center frequency of 600Hz extracted from the wide-band shear wave signal shown in FIG. Figure 4B , Figure 4C It can be seen that the vibration waveforms of shear wave components of different frequencies are different, which means that among the shear waves emitted in step S110, the vibration states of the tissue caused by the propagation of shear waves of different frequencies in the tissue are different.

[0100] As described above, the shear wave signal may be a time domain signal describing the temporal variation of tissue motion information in the region of interest. The filtering of the shear wave signal may be performed in the time domain, that is, the shear wave signal may be filtered in the time domain.

[0101] As another implementation method, the shear wave signal can also be transformed into a frequency domain signal, and the frequency domain signal can be frequency-domain filtered. For example, the amplitudes of all frequency bands other than the required frequency band in the frequency domain signal can be set to zero, and then the frequency domain signal after frequency domain filtering can be inversely transformed into a time domain signal. Exemplarily, the transformation of the shear wave signal from the time domain to the frequency domain can be achieved by Fourier transformation, and the transformation of the shear wave signal from the frequency domain to the time domain can be achieved by inverse Fourier transformation.

[0102] In one embodiment, the shear wave component in the shear wave signal may be extracted based on various suitable filters. The filter used may be a software filter or a hardware filter additionally provided in the ultrasonic measurement system.

[0103] Exemplarily, as a more accurate filtering method, filtering can be performed based on at least two bandpass filters of different frequencies with different frequencies as the center frequency to extract the shear wave components at the corresponding frequencies. For example, bandpass filters of 300 Hz and 600 Hz can be used respectively to extract shear wave components with 300 Hz and 600 Hz as the center frequencies from a wide-band shear wave signal of 0 to 1000 Hz. It is understandable that when filtering with a bandpass filter, more than two bandpass filters can be used to extract shear wave components of multiple frequencies from the shear wave signal.

[0104] In addition, as a relatively simplified filtering method, the shear wave signal can be filtered using a low-pass filter and a high-pass filter respectively, so as to extract the low-frequency component and the high-frequency component in the shear wave signal respectively. For example, a 500 Hz high-pass filter and a low-pass filter can be used to extract the low-frequency component of 0 to 500 Hz and the high-frequency component of 500 to 1000 Hz from the wide-band shear wave signal of 0 to 1000 Hz.

[0105] Further, from Figure 3 and Figure 4B , Figure 4C It can be seen that the separated shear wave components of each frequency do not necessarily include only a single frequency, namely the center frequency, but include a frequency band with a preset bandwidth having a preset frequency point as the center frequency.

[0106] Taking the central frequency as 300 Hz as an example, the frequency distribution of the extracted shear wave component can be a frequency range mainly around 300 Hz, such as 250-350 Hz, or 200-400 Hz. Figure 3 As shown, the center frequency of the shear wave component is at 300 Hz, and it also contains shear wave components of a certain bandwidth. By adjusting the filter parameters used for filtering, the bandwidth of the extracted shear wave components can be changed. The more concentrated the separated and extracted shear wave components are, the more accurate the tissue motion information at the current frequency can be obtained. However, correspondingly, since more shear wave components are filtered out, the signal-to-noise ratio of the obtained signal will be reduced. Therefore, by adjusting the filter parameters, the desired balance can be obtained between the accuracy of tissue motion information and the signal-to-noise ratio of the signal.

[0107] In step S150, the phase velocity of the shear wave is determined according to at least two shear wave components of different frequencies.

[0108] Specifically, the shear wave propagation velocity can be calculated based on the original shear wave signal obtained in step S130, or based on the shear wave components of different frequencies extracted through frequency separation. Since the shear wave source has a wider frequency band information, the shear wave propagation velocity calculated based on the original shear wave signal is the combined propagation velocity of shear waves of multiple frequencies, which is called the shear wave group velocity. The shear wave propagation velocity calculated using the separated shear wave components is the shear wave propagation velocity at this frequency, and is therefore called the shear wave phase velocity.

[0109] Exemplarily, the phase velocity of the shear wave can be calculated by various methods used in conventional shear wave elasticity measurements to determine the shear wave propagation velocity, such as calculating the shear wave propagation velocity by calculating the arrival time of the shear wave at two different locations in the tissue that are a certain distance apart. Specifically, the displacement-time curves corresponding to the two different locations in the tissue can be cross-correlated and compared to obtain the time difference between the two, which corresponds to the propagation time of the shear wave between the two locations. The ratio of the distance between the two locations to the propagation time is the shear wave propagation velocity. Alternatively, the shear wave propagation velocity can be calculated by inversion of the wave equation, etc. The embodiment of the present application does not limit the method for calculating the shear wave propagation velocity.

[0110] In step S160, viscosity information reflecting the viscosity of the region of interest is determined according to at least two of the phase velocities.

[0111] For pure elastic bodies, the shear wave propagation velocity is mainly affected by the elastic parameters. For viscoelastic bodies, the shear wave velocity is affected by both elasticity and viscosity. Due to the influence of viscosity factors, the shear wave propagation velocity in the tissue will show a dispersion effect, that is, the propagation velocities of shear waves of different frequencies are different. Therefore, the viscosity parameter of the region of interest can be determined based on the relationship between the viscosity parameter and the phase velocity determined in step S150 and the corresponding shear wave frequency, as viscosity information reflecting the viscosity of the tissue in the region of interest. According to an embodiment of the present application, the viscosity parameter can be determined based on the ultrasonic measurement data obtained in a single transmission and reception process, or the viscosity parameter and the elastic parameter can be obtained at the same time, without repeating multiple acoustic radiation force impacts and echo acquisition processes.

[0112] Specifically, the viscosity parameters can be determined according to a variety of theoretical models. For example, according to the Voigt model, the phase velocity c of the shear wave is φ The relationship between it and the viscosity parameter is as follows:

[0113]

[0114] Wherein, ρ is tissue density, μ1 is tissue elasticity parameter (shear elasticity), μ2 is tissue viscosity parameter (shear viscosity), ω is the angular frequency of the shear wave, and the angular frequency of the shear wave can be determined according to the center frequency of the shear wave component. Specifically, the angular frequency is 2π times the center frequency.

[0115] According to the above formula, at least the propagation speeds of two shear wave components of different frequencies need to be calculated to calculate the viscosity parameters of the tissue. Of course, in some embodiments, in order to more accurately calculate the viscosity parameters of the tissue, the propagation speeds of multiple shear wave components of different frequencies can be calculated, and then the above formula is used for fitting to obtain the best estimate of the viscosity parameters. Among them, multiple shear wave components of different frequencies can be separated and extracted from the shear wave signal obtained from a single acoustic radiation force impact and echo acquisition process, or they can be separated and extracted from the shear wave signal obtained from multiple acoustic radiation force impacts and echo acquisition processes.

[0116] Of course, more simply, since the shear wave propagation velocity is related to the tissue viscosity, the difference in phase velocities of the shear wave components of different frequencies can be directly used to reflect the viscosity of the tissue, that is, the phase velocities determined according to the shear wave components of different frequencies are compared to obtain a comparison result, and the comparison result is used as the viscosity information reflecting the viscosity of the region of interest.

[0117] For example, the difference in phase velocity of shear wave components of different frequencies, the ratio of phase velocities, the slope of the phase velocity changing with the shear wave frequency, and other related parameters can be calculated to reflect viscosity. For example, a linear fit can be performed based on multiple shear wave frequencies and corresponding phase velocities to obtain a phase velocity-frequency straight line and obtain the slope of the straight line. This straight line slope reflects the changing relationship between the phase velocity and the shear wave frequency when the shear wave passes through the same tissue position, and can qualitatively reflect the viscosity characteristics of the tissue. That is, the larger the slope, the greater the tissue viscosity; conversely, the smaller the slope, the smaller the tissue viscosity.

[0118] In addition, according to the above-mentioned Voigt model, it can be found that in addition to the viscosity parameter μ2, the first elastic parameter of the region of interest (i.e., the elastic parameter μ1) can also be calculated based on the relationship between the phase velocity and the viscosity parameter μ2, the elastic parameter μ1, and the shear wave frequency. The first elastic parameter is different from the elastic modulus calculated based on the shear wave group velocity (i.e., the second elastic parameter described below), but the first elastic parameter can also reflect the elastic characteristics of the tissue. Therefore, in one embodiment, the elastic parameter μ1 can also be output as an elastic measurement result reflecting the elasticity of the tissue.

[0119] In addition, the viscoelasticity measurement method 100 of the embodiment of the present application can also reuse the same set of first ultrasonic echo data to obtain conventional elasticity measurement results.

[0120] Specifically, the group velocity of the shear wave can be determined according to the first ultrasonic echo data, and the second elastic parameter of the region of interest can be obtained according to the group velocity. The second elastic parameter can be the elastic modulus of the tissue, such as Young's modulus, shear modulus, etc. Under certain conditions, the larger the elastic modulus, the greater the hardness of the tissue. Exemplarily, the elastic modulus of the tissue can be calculated based on the following formula: Shear modulus G = ρc s 2 ; Young's modulus E = 3ρc s 2 ; where ρ is tissue density, c s is the shear wave group velocity.

[0121] In addition, in some embodiments, the elastic modulus of the tissue can also be calculated based on the phase velocity of the shear wave component of at least one frequency obtained by separation. Specifically, the corresponding shear modulus or Young's modulus can be calculated based on the phase velocity of the shear wave, for example, by using the shear wave phase velocity to replace the shear wave group velocity c s To calculate the above-mentioned shear modulus G or Young's modulus E. Since the elastic modulus calculated using the shear wave phase velocity corresponds to a fixed shear wave frequency, the stability of elasticity measurement can be improved.

[0122] In step S170, the viscosity information is output.

[0123] The output viscosity information may include a value and / or an image of an output viscosity parameter.

[0124] For outputting the value of the viscosity parameter, in one embodiment, the viscosity parameters can be obtained for multiple positions in the region of interest, and the distribution of the viscosity parameters in the region of interest can be displayed. For example, after determining the viscosity parameters at multiple positions in the region of interest, they can be displayed at corresponding positions of a conventional ultrasound image to form a viscosity parameter distribution diagram to intuitively display the difference in tissue viscosity.

[0125] In another embodiment, the outputted value of the viscosity parameter may be the value of the statistical result of the viscosity parameter, so as to estimate the overall viscosity of the region of interest. Specifically, the statistical result of the viscosity information of the region of interest may be obtained according to the viscosity information at one or more positions in the region of interest, and the value of the statistical result may be output. The statistical result of the viscosity information may include at least one of the following: the average value, median value, standard deviation, quartile, maximum value or minimum value of the plurality of viscosity information.

[0126] Furthermore, the statistical results of the viscosity information are not limited to the statistical results of the viscosity information at multiple positions obtained by one viscoelasticity measurement, but may also include the statistical results of the viscosity information obtained by multiple viscoelasticity measurements. Exemplarily, the statistical results of the viscosity information obtained by multiple viscoelasticity measurements may also include the average value, median, standard deviation, quartile, maximum value or minimum value, etc. of the viscosity information obtained by multiple viscoelasticity measurements.

[0127] For outputting the image of viscosity information, specifically, the viscosity information at multiple positions in the region of interest can be obtained to generate a viscosity image of the region of interest, and the viscosity image is displayed on the display interface. For example, the viscosity parameters can be processed by grayscale or color coding to generate a viscosity image, which is superimposed or fused with a conventional ultrasound image and displayed together.

[0128] In addition to outputting the viscosity information, the elastic information of the tissue in the region of interest may also be output. The elastic information may be displayed synchronously with the viscosity information, for example, on the same display interface; or, the elastic information may be displayed separately from the viscosity information. The elastic information may include the first elastic parameter, the second elastic parameter, or the elastic modulus calculated using the phase velocity, and outputting the elastic information may include outputting the numerical value and / or image of the first elastic parameter, the second elastic parameter, and / or the elastic modulus calculated using the phase velocity.

[0129] In addition, in one embodiment, the relevant information of the shear wave velocity can also be output. The relevant information of the shear wave velocity includes the shear wave group velocity information and the shear wave phase velocity information, and specifically can include the numerical value and / or image of the shear wave group velocity, and / or the numerical value and / or image of the shear wave phase velocity. When the numerical value of the shear wave group velocity or the numerical value of the shear wave phase velocity is output, it can also include outputting the numerical distribution of the shear wave group velocity or the phase velocity at multiple positions, or outputting the statistical results of the numerical values ​​of the shear wave group velocity or the phase velocity at multiple positions.

[0130] Furthermore, a conventional ultrasound image may be displayed while displaying the viscosity information and / or elasticity information of the region of interest. The conventional ultrasound image may be generated based on the first ultrasound echo data or based on the second ultrasound echo data. The conventional ultrasound image may be an image acquired in real time during the viscoelasticity measurement, an image acquired at regular intervals during the viscoelasticity measurement, or a non-real-time image acquired before each viscoelasticity measurement and no longer updated.

[0131] For example, when displaying the values ​​of the viscosity information and the elasticity information, the values ​​of the viscosity information and the elasticity information may be displayed at appropriate positions of the conventional ultrasound image, for example, Figure 6 As shown, it can be displayed at the lower right corner of the conventional ultrasound image, or it can also be displayed inside the region of interest. When the images of viscosity information and elasticity information are displayed, the viscosity image and the elasticity image can be superimposed on the conventional ultrasound image, for example, superimposed on the region of interest of the conventional ultrasound image. Figure 5A-5C ,in, Figure 5A shows a region of interest selected in a conventional ultrasound image, Figure 5B shows an elastic image superimposed on a region of interest on a conventional ultrasound image, Figure 5C A viscous image is shown superimposed on a region of interest on a conventional ultrasound image.

[0132] The above is an exemplary illustration of a viscoelasticity measurement method 100 according to an embodiment of the present application. Based on the above description, the viscoelasticity measurement method 100 according to an embodiment of the present application extracts shear wave components of different frequencies in a shear wave signal and calculates the phase velocity of the shear wave components of different frequencies, and a single measurement can be performed to obtain viscosity information reflecting tissue viscosity.

[0133] Please refer to the attached Figure 7 A viscoelasticity measurement method according to another embodiment of the present application is described. Figure 7 FIG. 7 is a schematic flow chart of a viscoelasticity measurement method 700 according to another embodiment of the present application. Figure 7The viscoelasticity measurement method 700 described is substantially similar to the viscoelasticity measurement method 100 described above, and some of the same details are omitted. Figure 7 As shown, the viscoelasticity measurement method 700 includes the following steps:

[0134] Step S710, obtaining a shear wave signal of a region of interest of the object under test;

[0135] Step S720, extracting at least two shear wave components of different frequencies from the shear wave signal;

[0136] Step S730, determining the phase velocity of the shear wave according to the at least two shear wave components of different frequencies respectively;

[0137] Step S740: Determine viscosity information reflecting the viscosity of the region of interest according to at least two of the phase velocities.

[0138] In reference Figure 7 In the described embodiment, shear wave components of different frequencies are extracted from the shear wave signal, and viscosity information reflecting the viscosity of the region of interest is determined based on the phase velocity determined based on the shear wave components of at least two frequencies. Unlike the above-mentioned viscoelasticity measurement method 100, the viscoelasticity measurement method 700 does not limit the way of obtaining the shear wave signal: for example, the shear wave signal can be obtained in real time or extracted from a storage medium; the way of generating the shear wave can be either the acoustic radiation force pulse impact as described above, or it can be generated by applying external mechanical vibration, or it can be generated by any other suitable way.

[0139] According to the viscoelasticity measurement method 700 of the embodiment of the present application, by extracting shear wave components of different frequencies in the shear wave signal and calculating the phase velocities of the shear wave components of different frequencies, viscosity information reflecting tissue viscosity can be obtained through one measurement.

[0140] Please refer to the attached Figure 8 A method for measuring elasticity according to an embodiment of the present application is described. Figure 8 FIG. 8 is a schematic flow chart of an elasticity measurement method 800 according to an embodiment of the present application. Figure 8 As shown, the elasticity measurement method 800 may include the following steps:

[0141] In step S810, an acoustic radiation force pulse is emitted to the object to be measured to generate a broadband shear wave in a region of interest of the object to be measured;

[0142] In step S820, a first ultrasonic wave tracking the shear wave is transmitted to the region of interest, and a first ultrasonic echo of the region of interest is received to obtain first ultrasonic echo data;

[0143] In step S830, a shear wave signal of the region of interest is obtained according to the first ultrasonic echo data;

[0144] In step S840, a shear wave component of at least one frequency is extracted from the shear wave signal;

[0145] In step S850, the phase velocity of the shear wave is determined according to the shear wave component of the at least one frequency.

[0146] The viscoelasticity measurement method 800 of the embodiment of the present application adds a step of extracting shear wave components of different frequencies in the shear wave signal on the basis of conventional shear wave elasticity measurement, and calculates the phase velocity of the shear wave based on the separated shear wave components. The phase velocity can be used to determine the elasticity information or viscosity information of the tissue.

[0147] Generally, before executing step S810, the position of the region of interest is first determined according to a conventional ultrasound image of the object under test.

[0148] Specifically, a second ultrasonic wave can be emitted to the object under test through an ultrasonic probe, and an ultrasonic echo of the second ultrasonic wave can be received to obtain second ultrasonic echo data. Afterwards, the second ultrasonic echo data can be subjected to beam synthesis processing by a beam synthesis circuit, and then the beam synthesized second ultrasonic echo data is sent to a processor for relevant image processing, thereby obtaining a basic ultrasonic image. Afterwards, the position of the region of interest can be determined based on the basic ultrasonic image. In one example, determining the position of the region of interest based on a conventional ultrasonic image specifically includes: outputting the conventional ultrasonic image, and marking the position of the region of interest on the conventional ultrasonic image.

[0149] Next, in step S810 to step S830, the acoustic radiation force focused impact can be performed according to the position of the region of interest selected in the above manner and in accordance with a pre-set pulse sequence. Specifically, the ultrasonic probe emits a special ultrasonic push pulse to the tissue of the region of interest of the object under test to generate the propagation of shear waves in the tissue based on the acoustic radiation force. The length of the ultrasonic push pulse is generally greater than 100us, and in order to enhance the intensity and range of the generated shear wave, multiple ultrasonic push pulses are often emitted continuously.

[0150] Next, the ultrasonic probe continuously emits a series of first ultrasonic waves that track the shear wave to the tissue in the area of ​​interest for a period of time, and receives its ultrasonic echo to obtain first ultrasonic echo data, and obtains a shear wave signal based on the first ultrasonic echo data, and the shear wave signal is used to characterize the vibration state of the tissue when the shear wave propagates in the tissue. The shear wave signal obtained by the above method is a broadband signal, which includes shear wave components of multiple frequencies within 0 to 1000 Hz, and each shear wave component of the shear wave signal is equivalent to characterizing the tissue vibration state caused by a shear wave of one frequency.

[0151] In step S840, the shear wave signal is filtered to extract a shear wave component of at least one frequency. Shear wave components of different frequencies can be regarded as tissue vibration information caused by shear waves of different frequencies. The shear wave signal can be a time domain signal that describes the change of tissue movement information in the region of interest over time, and the filtering of the shear wave signal can be performed in the time domain, that is, the shear wave signal is filtered in the time domain. As another implementation method, the shear wave signal can also be transformed into a frequency domain signal, and the frequency domain signal can be filtered in the frequency domain. Afterwards, the frequency domain signal after frequency domain filtering is inversely transformed into a time domain signal.

[0152] Exemplarily, filtering can be performed based on a bandpass filter with a selected frequency as the center frequency to extract the shear wave component at the corresponding frequency. In addition, the shear wave signal can be filtered using a low-pass filter and / or a high-pass filter.

[0153] Furthermore, each separated shear wave component does not necessarily include only a single frequency, namely the center frequency, but includes a frequency band with a preset bandwidth with a preset frequency point as the center frequency. The bandwidth of the extracted shear wave components can be changed by adjusting the filter parameters used for filtering. The more concentrated the separated and extracted shear wave components are, the more accurate the tissue movement information at the current frequency can be obtained. However, correspondingly, since more shear wave components are filtered out, the signal-to-noise ratio of the obtained signal will be reduced. Therefore, by adjusting the filter parameters, a desired balance can be achieved between the accuracy of tissue movement information and the signal-to-noise ratio of the signal.

[0154] In step S850, the phase velocity of the shear wave is determined according to the shear wave component. Exemplarily, the phase velocity of the shear wave can be calculated by various methods used in conventional shear wave elasticity measurement to determine the shear wave propagation velocity, such as calculating the shear wave propagation velocity by calculating the arrival time of the shear wave at two different positions separated by a certain distance in the tissue. Alternatively, the shear wave propagation velocity is also calculated by inversion of the wave equation, etc. The embodiment of the present application does not limit the method for calculating the shear wave propagation velocity.

[0155] Afterwards, the phase velocity of the shear wave can be directly output. The output phase velocity may include the numerical value and / or image of the output phase velocity. The numerical value of the output phase velocity may include the numerical value of the phase velocity at each position of the region of interest, or may include the statistical result of the numerical value of the phase velocity at multiple positions. The image of the output phase velocity may include a statistical graph of the output phase velocity or a phase velocity image formed by grayscale or color coding according to the numerical value of the phase velocity superimposed on a conventional ultrasound image, or may also include a curve of the phase velocity changing with the shear wave frequency, etc.

[0156] In one embodiment, the third elastic parameter of the region of interest can also be determined according to the phase velocity of the shear wave, and the value and / or image of the third elastic parameter can be output. The third elastic parameter can include the elastic modulus calculated using the phase velocity, or can include the elastic parameter calculated according to the Voigt model.

[0157] Exemplarily, the outputted value of the third elastic parameter may be a value of a statistical result of the third elastic parameter, as an estimate of the overall elasticity of the region of interest. The statistical result of the third elastic parameter may include at least one of the following: an average value, a median value, a standard deviation, a quartile, a maximum value, or a minimum value of the plurality of elastic information.

[0158] Furthermore, the statistical result of the third elastic parameter is not limited to the statistical result of the third elastic parameter at multiple positions obtained by one elastic measurement, but may also include the statistical result of the third elastic parameter obtained by multiple elastic measurements. Exemplarily, the statistical result of the third elastic parameter obtained by multiple elastic measurements may also include the mean value, median, standard deviation, quartile, maximum value or minimum value, etc. of the third elastic parameter obtained by multiple elastic measurements.

[0159] For outputting the image of the third elastic parameter, specifically, the third elastic parameter at multiple positions in the region of interest can be obtained to generate an elastic image of the region of interest, and the elastic image is displayed on the display interface. For example, the third elastic parameter can be processed by grayscale or color coding to generate an elastic image, which is superimposed or fused with a conventional ultrasound image and displayed together.

[0160] In one embodiment, the group velocity of the shear wave can also be determined according to the shear wave signal, and the fourth elastic parameter of the region of interest can be obtained according to the group velocity, and then the value and / or image of the fourth elastic parameter can also be output. The fourth elastic parameter may include a shear modulus or Young's modulus calculated using the group velocity of the shear wave. The output method of the fourth elastic parameter can refer to the output method of the third elastic parameter above.

[0161] The above exemplifies an elasticity measurement method 800 according to an embodiment of the present application. Based on the above description, the elasticity measurement method 800 according to an embodiment of the present application extracts the shear wave component in the shear wave signal and calculates the phase velocity of the shear wave component, which can reflect information such as the elasticity or viscosity of the tissue in the region of interest.

[0162] Please refer to the attached Fig. 9 A method for measuring elasticity according to another embodiment of the present application is described. Fig. 9 FIG. 9 is a schematic flow chart of an elasticity measurement method 900 according to another embodiment of the present application. Fig. 9 The elasticity measurement method 900 described is substantially similar to the elasticity measurement method 800 described above, and some of the same details are omitted. Fig. 9 As shown, the elasticity measurement method 900 includes the following steps:

[0163] Step S910, obtaining a shear wave signal of a region of interest of the object under test;

[0164] Step S920, extracting a shear wave component of at least one frequency from the shear wave signal;

[0165] Step S930: determining the phase velocity of the shear wave according to the shear wave component of the at least one frequency.

[0166] refer to Fig. 9 The elasticity measurement method described in 900 is similar to that described in reference Figure 8 The elastic measurement method 8008 described is similar, both of which determine the phase velocity of the shear wave based on the shear wave component extracted from the shear wave signal. The difference is that in the elastic measurement method 900, the method for obtaining the shear wave signal is not limited, and the region of interest of the target object can be obtained in any suitable manner to perform the above-mentioned elastic measurement on it. For example, the shear wave signal can be acquired in real time or extracted from a storage medium; the method of generating the shear wave can be either the acoustic radiation force pulse impact as described above, or it can be generated by applying external mechanical vibration, or it can be generated in any other suitable manner.

[0167] According to the elasticity measurement method 900 of the embodiment of the present application, the shear wave component in the shear wave signal is extracted, and the phase velocity of the shear wave component is calculated. The phase velocity can reflect information such as the elasticity or viscosity of the tissue in the region of interest.

[0168] The above exemplary shows the elasticity measurement method according to the embodiment of the present application. Fig.10 An ultrasonic measurement system according to an embodiment of the present application is described, which can be used to implement the viscoelasticity measurement method or elasticity measurement method according to an embodiment of the present application described above. Fig.10A schematic structural block diagram of an ultrasonic measurement system 1000 according to an embodiment of the present application is shown.

[0169] like Fig.10 As shown, the ultrasound measurement system 1000 includes an ultrasound probe 1010, a transmit / receive circuit 1020, a processor 1030, and an output device 1040. Further, the ultrasound measurement system may also include a beamforming circuit and a transmit / receive selection switch, and the transmit / receive circuit 1020 may be connected to the ultrasound probe 1010 through the transmit / receive selection switch.

[0170] Wherein, when performing shear wave elasticity measurement, the ultrasonic probe 1010 transmits an acoustic radiation force pulse to the object under the control of the processor 1030 to generate shear waves in the area of ​​interest of the object under test. A plurality of transducers are provided in the ultrasonic probe 1010 for transmitting ultrasonic waves according to electrical signals, or for converting received ultrasonic echoes into electrical signals. A plurality of transducers can be arranged in a row to form a linear array, or arranged in a two-dimensional matrix to form a planar array. A plurality of transducers can also form a convex array, a phased array, etc. The embodiment of the present application does not limit the arrangement of the plurality of transducer array elements.

[0171] The transducer can transmit ultrasonic waves according to the excitation electrical signal, or convert the received ultrasonic waves into electrical signals, so each transducer can be used to transmit ultrasonic waves to the tissue of the target area, and can also be used to receive ultrasonic echoes returned through the tissue. When performing ultrasonic measurement, the transmitting / receiving circuit 1020 can control which transducers are used to transmit ultrasonic waves and which transducers are used to receive ultrasonic waves, or control the transducers to transmit ultrasonic waves or receive ultrasonic echoes in time slots. All transducers participating in ultrasonic emission can be excited by electrical signals at the same time, thereby transmitting ultrasonic waves at the same time; or the transducers participating in ultrasonic emission can also be excited by several electrical signals with a certain time interval, thereby continuously transmitting ultrasonic waves with a certain time interval.

[0172] The region of interest may be selected by the user, for example, when a conventional ultrasound image is displayed on the display, the user may select the region of interest on the conventional ultrasound image, and the ultrasound measurement system 1000 may calculate the transmission and reception sequences according to the selected region of interest. In some embodiments, the ultrasound measurement system 1000 defaults to the subcutaneous setting range of the tissue contacted by the ultrasound probe 1010 as the region of interest.

[0173] Optionally, the ultrasonic probe 1010 may also include a pressure sensor for feeding back the force of contact between the ultrasonic probe 1010 and the human body, so that the user can control the tightness of the pressure and the shear wave generated by the ultrasonic probe 1010 can be better transmitted into the tissue.

[0174] The transmitting / receiving circuit 1020 is used to stimulate the ultrasonic probe 1010 to transmit an ultrasonic wave that tracks the shear wave to the target area, and receive an ultrasonic echo corresponding to the ultrasonic wave returned from the target area, thereby obtaining ultrasonic echo data. Afterwards, the transmitting / receiving circuit 1020 sends the electrical signal of the ultrasonic echo to the beamforming circuit, which performs focusing delay, weighting and channel summing on the ultrasonic echo data, and then sends it to the processor 1030.

[0175] Optionally, the processor 1030 may be implemented by software, hardware, firmware or any combination thereof, and may be implemented by circuits, single or multiple application specific integrated circuits (ASICs), single or multiple general purpose integrated circuits, single or multiple microprocessors, single or multiple programmable logic devices, or any combination of the aforementioned circuits and / or devices, or other suitable circuits or devices. Furthermore, the processor 1030 may control other components in the ultrasonic measurement system 1000 to perform desired functions.

[0176] The processor 1030 performs viscoelastic processing on the ultrasonic echo data it receives to obtain viscosity information and elastic information of the region of interest, and can store the obtained viscosity information and elastic information in the memory. As an example, the processor can also perform different processing on the ultrasonic echo data acquired by the transmitting / receiving circuit 1020 according to the imaging mode required by the user to obtain ultrasonic tissue images of different modes. In one embodiment, the processor can simultaneously obtain viscosity information, elastic information and ultrasonic tissue images after processing the same ultrasonic echo; in another embodiment, the ultrasonic probe 1010 can transmit the first ultrasonic wave and the second ultrasonic wave successively or transmit the first ultrasonic wave and the second ultrasonic wave interspersedly, and the processor 1030 can obtain viscosity information and elastic information after processing the first ultrasonic echo of the first ultrasonic wave, and generate ultrasonic tissue images of different modes after processing the second ultrasonic echo of the second ultrasonic wave.

[0177] The output device 1040 is connected to the processor 1030 and is used to output the viscosity information and the elasticity information. In one embodiment, the output device 1040 may be a display, which is used to display the viscosity information and the elasticity information on a display interface. As an example, the display may be a touch screen, a liquid crystal display, etc., or may be an independent display device such as an independent liquid crystal display, a television, etc.; or the display may be a display screen of an electronic device such as a smart phone, a tablet computer, etc. The number of displays may be one or more.

[0178] In addition to displaying ultrasound images, the display can also provide users with a graphical interface for human-computer interaction. One or more controlled objects are set on the graphical interface, and the user is provided with a human-computer interaction device to input operation instructions to control these controlled objects, thereby performing corresponding control operations. For example, an icon is displayed on the graphical interface, and the icon can be operated using the human-computer interaction device to perform a specific function.

[0179] In addition, the output device 1040 may also include a speaker, a printer, etc. The output device 1040 may also be any other suitable information output device.

[0180] Optionally, the ultrasonic measurement system 1000 may further include other human-machine interaction devices, which are connected to the processor 1030. For example, the processor 1030 may be connected to the human-machine interaction device via an external input / output port, and the external input / output port may be a wireless communication module, or a wired communication module, or a combination of the two. The external input / output port may also be implemented based on USB, bus protocols such as CAN, and / or wired network protocols.

[0181] Exemplarily, the human-computer interaction apparatus may include an input device for detecting user input information, which may be, for example, a selection instruction for an area of ​​interest, or may also include other instruction types. The input device may include a keyboard, a mouse, a scroll wheel, a trackball, a mobile input device (such as a mobile device with a touch screen, a mobile phone, etc.), a multi-function knob, etc., or a combination of multiple thereof.

[0182] The ultrasonic measurement system 1000 may also include a memory for storing instructions executed by the processor, storing viscosity information and elasticity information, ultrasonic images, etc. The memory may be a flash memory card, a solid-state memory, a hard disk, etc. It may be a volatile memory and / or a non-volatile memory, a removable memory and / or a non-removable memory, etc.

[0183] It should be understood that Fig.10 The components included in the ultrasonic measurement system 1000 are merely illustrative, and the system may include more or fewer components, which is not limited in the present application.

[0184] In one embodiment, the ultrasonic measurement system 1000 is used to implement the viscoelasticity measurement method 100 of the embodiment of the present application, and the transmitting / receiving circuit 1020 is used to stimulate the ultrasonic probe 1010 to transmit an acoustic radiation force pulse to the object to be measured to generate a shear wave in the region of interest of the object to be measured, and to stimulate the ultrasonic probe 1010 to transmit a first ultrasonic wave to the region of interest to track the shear wave, and receive a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data; the processor 1030 is used to: obtain a shear wave signal of the region of interest based on the first ultrasonic echo data; extract at least two shear wave components of different frequencies from the shear wave signal; determine the phase velocity of the shear wave based on the at least two shear wave components of different frequencies respectively; determine viscosity information reflecting the viscosity of the region of interest based on at least two phase velocities; the output device 1040 is used to output the viscosity information.

[0185] In one embodiment, the ultrasonic measurement system 1000 is used to implement the elasticity measurement method 800 of the embodiment of the present application, and the transmitting / receiving circuit 1020 is used to stimulate the ultrasonic probe 1010 to transmit an acoustic radiation force pulse to the object to be measured to generate a shear wave in the region of interest of the object to be measured; and to stimulate the ultrasonic probe 1010 to transmit a first ultrasonic wave to the region of interest to track the shear wave, and receive a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data; the processor 1030 is used to: obtain a shear wave signal of the region of interest based on the first ultrasonic echo data; extract a shear wave component of at least one frequency from the shear wave signal; determine the phase velocity of the shear wave based on the shear wave component of at least one frequency; the output device 1040 is used to output the phase velocity of the shear wave.

[0186] The above exemplifies the ultrasonic measurement system 1000 according to the embodiment of the present application. Based on the above description, the ultrasonic measurement system 1000 according to the embodiment of the present application can be used to extract shear wave components of different frequencies from the shear wave signal to determine the viscosity information of the tissue, and can be used to extract shear wave components of at least one frequency from the shear wave signal to determine the phase velocity of the tissue.

[0187] Reference Fig.11 The embodiment of the present application further provides an ultrasonic measurement system 1100 for implementing the viscoelasticity measurement method 70 or the elasticity measurement method 900. The ultrasonic measurement system 1100 includes a memory 1110 and a processor 1120, and the memory 1110 stores a computer program executed by the processor 1120.

[0188] The processor 1120 may be implemented by software, hardware, firmware or any combination thereof, and may use circuits, single or multiple dedicated integrated circuits, single or multiple general-purpose integrated circuits, single or multiple microprocessors, single or multiple programmable logic devices, or any combination of the aforementioned circuits and / or devices, or other suitable circuits or devices, and the processor 1120 may control other components in the ultrasonic measurement system 1100 to perform desired functions.

[0189] The memory 1110 may include one or more computer program products, and the computer program product may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory and / or cache memory, etc. The non-volatile memory may include, for example, read-only memory, hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 520 may run the program instructions to implement the functions of ultrasonic imaging or ultrasonic image processing in the embodiments of the present invention (implemented by the processor) described below and / or other various desired functions. Various applications and various data, such as various data used and / or generated by the application, may also be stored in the computer-readable storage medium.

[0190] In one embodiment, the computer program stored on the memory 1110 performs the following steps when executed by the processor 1120: obtaining a shear wave signal of a region of interest of the object under test; extracting at least two shear wave components of different frequencies from the shear wave signal; determining the phase velocities of the shear wave based on the at least two shear wave components of different frequencies respectively; and determining viscosity information reflecting the viscosity of the region of interest based on at least two phase velocities.

[0191] In another embodiment, the computer program stored on the memory 1110 performs the following steps when executed by the processor 1120: acquiring a shear wave signal of a region of interest of the object under test; extracting a shear wave component of at least one frequency from the shear wave signal; and determining the phase velocity of the shear wave based on the shear wave component of at least one frequency.

[0192] For other specific details of the functions implemented by the ultrasonic measurement system 1100, please refer to the relevant description in the method section above, which will not be repeated here.

[0193] In addition, according to an embodiment of the present application, a storage medium is also provided, on which program instructions are stored, and when the program instructions are run by a computer or a processor, they are used to execute the corresponding steps of the viscoelasticity measurement method 200, the viscoelasticity measurement method 700, the elasticity measurement method 800, or the elasticity measurement method 900 of the embodiment of the present application. The storage medium may include, for example, a memory card of a smart phone, a storage component of a tablet computer, a hard disk of a personal computer, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disk read-only memory (CD-ROM), a USB memory, or any combination of the above storage media. The computer-readable storage medium may be any combination of one or more computer-readable storage media.

[0194] In addition, according to an embodiment of the present application, a computer program is also provided, which can be stored in a cloud or local storage medium. When the computer program is run by a computer or a processor, it is used to perform the corresponding steps of the viscoelasticity measurement method or elasticity measurement method of the embodiment of the present application.

[0195] Based on the above description, the viscoelasticity measurement method and ultrasonic measurement system according to the embodiment of the present application extract shear wave components of different frequencies from the shear wave signal and obtain the phase velocity of each shear wave component, and only one measurement is required to obtain information reflecting the viscosity of the tissue. The elasticity measurement method according to the embodiment of the present application extracts the shear wave component from the shear wave signal and calculates its corresponding phase velocity, which can reflect the elasticity information of the tissue.

[0196] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0197] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0198] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0199] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0200] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0201] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0202] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0203] The various component embodiments of the present application can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It should be understood by those skilled in the art that a microprocessor or digital signal processor (DSP) can be used in practice to implement some or all functions of some modules according to the embodiments of the present application. The application can also be implemented as a device program (e.g., computer program and computer program product) for executing a part or all of the methods described herein. Such a program implementing the present application can be stored on a computer-readable medium, or can have the form of one or more signals. Such a signal can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0204] It should be noted that the above embodiments illustrate rather than limit the present application, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation to the claims. The present application may be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

[0205] The above is only a specific implementation or description of a specific implementation of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A viscoelasticity measurement method, characterized in that: The method comprises: Acquiring a conventional ultrasound image of the object under test; determining a region of interest according to the conventional ultrasound image; Acquiring a shear wave signal of the region of interest, wherein the shear wave signal is used to characterize a vibration state of the tissue corresponding to the region of interest when the shear wave propagates in the tissue; extracting at least two shear wave components of different frequencies from the shear wave signal; Determining viscosity information reflecting the viscosity of the region of interest according to at least two shear wave components of different frequencies; The stickiness information is output.

2. The viscoelasticity measurement method according to claim 1, characterized in that: The shear wave component of each frequency includes a frequency band with a preset bandwidth and a preset frequency point as a center frequency.

3. The viscoelasticity measurement method according to claim 1, characterized in that: The shear wave signal is a broadband signal, and extracting at least two shear wave components of different frequencies from the shear wave signal includes: performing bandpass filtering on the shear wave signal based on at least two bandpass filters of different frequencies to respectively extract shear wave components of corresponding frequencies.

4. The viscoelasticity measurement method according to claim 1, characterized in that: The shear wave signal is a broadband signal, and extracting at least two shear wave components of different frequencies from the shear wave signal includes: filtering the shear wave signal based on a high-pass filter and a low-pass filter respectively to extract the high-frequency component and the low-frequency component in the shear wave signal.

5. The viscoelasticity measurement method according to claim 1, characterized in that: The shear wave signal includes a time domain signal describing the change of tissue motion information in the region of interest over time, and extracting at least two shear wave components of different frequencies from the shear wave signal includes: Performing time domain filtering on the shear wave signal, or The shear wave signal is transformed into a frequency domain signal, the frequency domain signal is frequency-domain filtered, and the frequency domain signal after the frequency domain filtering is inversely transformed into a time domain signal.

6. The viscoelasticity measurement method according to any one of claims 1 to 5, characterized in that: The viscosity information includes a viscosity parameter, and the viscosity information reflecting the viscosity of the region of interest is determined according to at least two shear wave components of different frequencies, including: Determining the phase velocity of the shear wave according to at least two shear wave components of different frequencies respectively; The viscosity parameter of the region of interest is determined according to the relationship between the phase velocity and the viscosity parameter and the shear wave frequency, wherein the shear wave frequency is determined according to the center frequency of the shear wave component.

7. The viscoelasticity measurement method according to claim 6, characterized in that: The determining of the viscosity parameter of the region of interest according to the relationship between the shear wave phase velocity, the viscosity parameter and the shear wave frequency comprises: Fitting is performed according to a plurality of the shear wave frequencies and their corresponding phase velocities to obtain the viscosity parameter.

8. The viscoelasticity measurement method according to claim 6, characterized in that: Also includes: Calculating a first elastic parameter of the region of interest according to a relationship between the phase velocity and a viscosity parameter, a first elastic parameter and a shear wave frequency; Output the value and / or image of the first elastic parameter.

9. The viscoelasticity measurement method according to any one of claims 1 to 5, characterized in that: The determining of the viscosity information reflecting the viscosity of the region of interest according to at least two shear wave components of different frequencies comprises: Determining the phase velocity of the shear wave according to at least two shear wave components of different frequencies respectively; The phase velocities determined according to the shear wave components of different frequencies are compared to obtain a comparison result, and the comparison result is used as the viscosity information reflecting the viscosity of the region of interest.

10. The viscoelasticity measurement method according to claim 9, characterized in that: The comparison result includes at least one of the following: a difference between the different phase velocities, a ratio of the different phase velocities, or a slope of the phase velocity changing with the shear wave frequency.

11. The viscoelasticity measurement method according to claim 1, characterized in that: Also includes: Acquiring the viscosity information at a plurality of positions in the region of interest to generate a viscosity image of the region of interest; The outputting the stickiness information includes displaying the stickiness image.

12. The viscoelasticity measurement method according to any one of claims 1 to 5, characterized in that: Also includes: Obtaining statistical results of the viscosity information of the region of interest according to the viscosity information at one or more locations within the region of interest; The outputting the viscosity information includes displaying a numerical value of the statistical result.

13. The viscoelasticity measurement method according to claim 12, characterized in that: The statistical result of the stickiness information includes at least one of the following: an average value, a median value, a standard deviation, a quartile, a maximum value or a minimum value of a plurality of the stickiness information.

14. The viscoelasticity measurement method according to claim 12 or 13, characterized in that: The statistical result of the viscosity information includes the statistical result of the viscosity information obtained by multiple viscoelasticity measurements.

15. The viscoelasticity measurement method according to claim 1 or 8, characterized in that: The step of obtaining a conventional ultrasonic image of the object under test comprises: Transmitting a second ultrasonic wave to the object under test, and receiving an ultrasonic echo of the second ultrasonic wave to obtain second ultrasonic echo data; A conventional ultrasound image of the object under test is obtained according to the second ultrasound echo data.

16. The viscoelasticity measurement method according to claim 15, characterized in that: Also includes: The conventional ultrasound image is output, and the position of the region of interest is marked on the conventional ultrasound image.

17. The viscoelasticity measurement method according to claim 1 or 16, characterized in that: Also includes: A group velocity of the shear wave is determined according to the shear wave signal, and a second elastic parameter of the region of interest is obtained according to the group velocity.

18. The viscoelasticity measurement method according to claim 17, characterized in that: Also includes: Output at least one of the following: The value of the second elastic parameter, the image of the second elastic parameter, the value of the group velocity, the image of the group velocity.

19. The viscoelasticity measurement method according to any one of claims 1 to 18, characterized in that: The step of obtaining a shear wave signal of a region of interest of the measured object comprises: transmitting an acoustic radiation force pulse to the object to be measured to generate a shear wave in a region of interest of the object to be measured; Transmitting a first ultrasonic wave tracking the shear wave to the region of interest, and receiving a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data; A shear wave signal of the region of interest is obtained according to the first ultrasonic echo data.

20. The method according to claim 19, characterized in that The step of obtaining the shear wave signal of the region of interest according to the first ultrasonic echo data comprises: Tissue motion information is determined according to the first ultrasonic echo data corresponding to different moments, and the tissue motion information is used as the shear wave signal; wherein the tissue motion information includes at least one of the tissue motion displacement, tissue motion speed, tissue motion acceleration and tissue strain.

21. The method according to claim 20, characterized in that Also includes: The vibration waveform of the shear wave signal is determined according to the tissue movement information at different moments, wherein the vibration waveform includes a tissue movement speed-time curve or a tissue movement displacement-time curve.

22. A viscoelasticity measurement method, characterized in that: The method comprises: Acquire a shear wave signal of a region of interest of the measured object, wherein the shear wave signal is used to characterize the vibration state of the tissue corresponding to the region of interest when the shear wave propagates in the tissue; extracting at least two shear wave components of different frequencies from the shear wave signal; Determining viscosity information reflecting the viscosity of the region of interest according to at least two shear wave components of different frequencies; The stickiness information is output.

23. The viscoelasticity measurement method according to claim 22, characterized in that: The method further comprises: determining a group velocity of the shear wave according to the shear wave signal, and obtaining a second elastic parameter of the region of interest according to the group velocity; At least one of a value of the second elastic parameter, an image of the second elastic parameter, a value of the group velocity, and an image of the group velocity is output.

24. The viscoelasticity measurement method according to claim 22, characterized in that: The viscosity information includes a viscosity parameter, and the viscosity information reflecting the viscosity of the region of interest is determined according to at least two shear wave components of different frequencies, including: Determining the phase velocity of the shear wave according to at least two shear wave components of different frequencies respectively; The viscosity parameter of the region of interest is determined according to the relationship between the phase velocity and the viscosity parameter and the shear wave frequency, wherein the shear wave frequency is determined according to the center frequency of the shear wave component.

25. The viscoelasticity measurement method according to claim 24, characterized in that: Also includes: Calculating a first elastic parameter of the region of interest according to a relationship between the phase velocity and a viscosity parameter, a first elastic parameter and a shear wave frequency; Output the value and / or image of the first elastic parameter.

26. The viscoelasticity measurement method according to claim 22, characterized in that: Also includes: Acquiring the viscosity information at a plurality of positions in the region of interest to generate a viscosity image of the region of interest; The outputting the stickiness information includes displaying the stickiness image.

27. The viscoelasticity measurement method according to claim 22, characterized in that: The step of obtaining a shear wave signal of a region of interest of the measured object comprises: Transmitting a first ultrasonic wave tracking the shear wave to the region of interest, and receiving a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data; Tissue motion information is determined according to the first ultrasonic echo data corresponding to different moments, and the tissue motion information is used as the shear wave signal; wherein the tissue motion information includes at least one of the tissue motion displacement, tissue motion speed, tissue motion acceleration and tissue strain.

28. The viscoelasticity measurement method according to claim 27, characterized in that: Also includes: The vibration waveform of the shear wave signal is determined according to the tissue movement information at different moments, wherein the vibration waveform includes a tissue movement speed-time curve or a tissue movement displacement-time curve.

29. The viscoelasticity measurement method according to any one of claims 22 to 28, characterized in that: Also includes: Obtaining statistical results of the viscosity information of the region of interest according to the viscosity information at one or more locations within the region of interest; The outputting the viscosity information includes displaying a numerical value of the statistical result.

30. The viscoelasticity measurement method according to claim 29, characterized in that: The statistical result of the stickiness information includes at least one of the following: an average value, a median value, a standard deviation, a quartile, a maximum value or a minimum value of a plurality of the stickiness information.

31. The viscoelasticity measurement method according to claim 22, characterized in that: The shear wave signal is a broadband signal, and extracting at least two shear wave components of different frequencies from the shear wave signal includes: performing bandpass filtering on the shear wave signal based on at least two bandpass filters of different frequencies to respectively extract shear wave components of corresponding frequencies.

32. A method for measuring elasticity, characterized in that: The method comprises: Acquire a shear wave signal of a region of interest of the measured object, wherein the shear wave signal is used to characterize the vibration state of the tissue corresponding to the region of interest when the shear wave propagates in the tissue; Extracting a shear wave component of at least one frequency from the shear wave signal; A shear wave velocity is determined based on the shear wave component of the at least one frequency.

33. The elasticity measurement method according to claim 32, characterized in that: The shear wave signal is a broadband signal, and extracting shear wave components of at least one frequency from the shear wave signal includes: performing bandpass filtering on the shear wave signal based on a bandpass filter to respectively extract shear wave components of corresponding frequencies.

34. The elasticity measurement method according to claim 32, characterized in that: The shear wave signal includes a time domain signal describing the change of tissue motion information in the region of interest over time, and extracting at least two shear wave components of different frequencies from the shear wave signal includes: Performing time domain filtering on the shear wave signal, or The shear wave signal is transformed into a frequency domain signal, the frequency domain signal is frequency-domain filtered, and the frequency domain signal after the frequency domain filtering is inversely transformed into a time domain signal.

35. The elasticity measurement method according to claim 32, characterized in that: The step of obtaining a shear wave signal of a region of interest of the measured object comprises: Transmitting a first ultrasonic wave tracking the shear wave to the region of interest, and receiving a first ultrasonic echo of the region of interest to obtain first ultrasonic echo data; Tissue motion information is determined according to the first ultrasonic echo data corresponding to different moments, and the tissue motion information is used as the shear wave signal; wherein the tissue motion information includes at least one of the tissue motion displacement, tissue motion speed, tissue motion acceleration and tissue strain.

36. The viscoelasticity measurement method according to claim 35, characterized in that: Also includes: The vibration waveform of the shear wave signal is determined according to the tissue movement information at different moments, wherein the vibration waveform includes a tissue movement speed-time curve or a tissue movement displacement-time curve.

37. The elasticity measurement method according to claim 34 or 35, characterized in that: Determining the shear wave velocity according to the shear wave component of the at least one frequency comprises: The shear wave velocity is determined according to tissue movement information corresponding to the time when the shear wave reaches different positions under at least one frequency of the shear wave component.

38. An ultrasonic measurement system, characterized in that: include: Ultrasound probe; A transmitting / receiving circuit, used for stimulating the ultrasonic probe to transmit ultrasonic waves to the object under test and receiving ultrasonic echoes; A processor, configured to execute the method according to any one of claims 1 to 37; An output device is used to output the result of the execution of the processor.

39. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a computer or a processor, the steps of the method according to any one of claims 1 to 37 are implemented.

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