Ultrasound blood pressure measurement method and system based on acoustic radiation force

Abstract

This invention relates to an ultrasonic blood pressure measurement method and system based on acoustic radiation force. It includes: constructing a pressure measurement equation for any vascular region of interest (ROI); calculating the pressure sensitivity A and the pressure intercept B by transmitting an acoustic radiation force signal to at least the vascular ROI and acquiring the subharmonic amplitude of the acoustic radiation force under each signal; calculating the pressure sensitivity A and the pressure intercept B in the pressure measurement equation based on each signal and its corresponding subharmonic amplitude; and during ultrasonic blood pressure measurement of the vascular ROI, acquiring the subharmonic amplitude of the vascular ROI under the optimal incident sound pressure and substituting the acquired subharmonic amplitude into the pressure measurement equation to generate the blood pressure value for the vascular ROI. This invention enables non-invasive blood pressure measurement using ultrasonic microbubble subharmonics, improving the convenience and operability of blood pressure measurement.

Description

Technical Field

[0001] This invention relates to a measurement method and system, and more particularly to an ultrasonic blood pressure measurement method and system based on acoustic radiation force. Background Technology

[0002] The technique of measuring blood pressure using subharmonics of ultrasonic microbubbles was first proposed by Shi et al. in 1999. They found that under ultrasonic excitation with certain specific acoustic parameters, the subharmonic, fundamental, and second harmonic components of the microbubble scattering signal monotonically decrease as the environmental pressure of the microbubble increases. Within the hydrostatic pressure range of 0-186 mmHg, the decrease in subharmonic amplitude is much greater than the decrease in the corresponding amplitudes of the fundamental and second harmonics.

[0003] During pressure measurement, the subharmonic response largely depends on the incident sound pressure. The subharmonic response generally refers to the amplitude of the corresponding subharmonic, meaning the relationship between subharmonics and blood pressure largely depends on the incident sound pressure. The specific relationship between subharmonics and blood pressure is consistent with existing technology and will not be elaborated here. With increasing incident sound pressure, the subharmonic response goes through the following stages: occurrence stage, growth stage, and saturation stage. During the growth stage, the subharmonic amplitude increases rapidly with increasing incident sound pressure. Studies have found that during this stage, the microbubble subharmonic signal is most sensitive to changes in hydrostatic pressure. Therefore, under suitable acoustic parameters, a linear relationship can be established between blood pressure and the subharmonic components of intravascular microbubbles using the following pressure measurement equation: Psh = A*P + B, where Psh is the subharmonic amplitude corresponding to ultrasound pressure measurement of the blood vessel (in dB), P is the intravascular blood pressure (in mmHg), A is the absolute value of the pressure measurement sensitivity (in dB / mmHg), and B is the pressure intercept.

[0004] When performing the above-mentioned intravascular manometry, it is necessary to solve for the manometry sensitivity A and the manometry intercept B in the manometry equation. Generally, when solving for the manometry sensitivity A and the manometry intercept B, the gold standard is often used, such as combining the accurate blood pressure value measured by the invasive pressure guidewire with the subharmonic amplitude value of the intravascular microbubble under synchronous ultrasound excitation. Theoretically, at least two sets of accurate blood pressure and corresponding subharmonic values ​​are sufficient to solve for the manometry sensitivity A and the manometry intercept B.

[0005] Understandably, when calculating the pressure sensitivity A and the pressure intercept B using the above method, the operation process clearly violates the original intention of non-invasive ultrasound pressure measurement, and compared with the traditional technique of invasive intravascular pressure measurement using a pressure guidewire, it does not have sufficient application scenario advantages.

[0006] In summary, in practical applications of blood pressure measurement using ultrasonic microbubble subharmonics, to ensure the non-invasive nature of the measurement process, it is often impossible to clearly define the blood pressure sensitivity A and the blood pressure intercept B in the blood pressure measurement equation. In other words, it is impossible to make a qualitative judgment on the blood pressure gradient solely based on the level of the subharmonic values. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology and provide an ultrasonic blood pressure measurement method and system based on acoustic radiation force, which can non-invasively realize blood pressure measurement using ultrasonic microbubble subharmonics, thereby improving the convenience and operability of blood pressure measurement.

[0008] According to the technical solution provided by the present invention, an ultrasonic blood pressure measurement method based on acoustic radiation force is provided, the ultrasonic blood pressure measurement method comprising:

[0009] For any vascular ROI region, construct a pressure measurement equation for the vascular ROI region, wherein, when constructing the pressure measurement equation, at least the pressure measurement sensitivity A and the pressure measurement intercept B within the pressure measurement equation are solved;

[0010] When calculating the pressure measurement sensitivity A and the pressure measurement intercept B, an acoustic radiation force signal is emitted at least to the vascular ROI region, and the amplitude of the acoustic radiation force subharmonic under each acoustic radiation force signal is obtained.

[0011] When emitting an acoustic radiation force signal to the vascular ROI region, at least the signal frequency of the acoustic radiation force signal is configured so that the sound pressure attenuation during the process of the acoustic radiation force signal entering the vascular ROI region matches the attenuation threshold, and the blood pressure fluctuation generated in the vascular ROI region under the acoustic radiation force signal can be observed.

[0012] Based on each acoustic radiation force signal and the corresponding acoustic radiation force subharmonic amplitude, the pressure measurement sensitivity A and pressure measurement intercept B in the pressure measurement equation are calculated.

[0013] When performing ultrasound blood pressure measurement on the vascular ROI region, the subharmonic amplitude of the pressure measurement in the vascular ROI region under the optimal incident sound pressure is obtained, and the obtained subharmonic amplitude of the pressure measurement is substituted into the pressure measurement equation to generate the blood pressure value of the vascular ROI region.

[0014] When acquiring the acoustic radiation force subharmonic amplitude under each acoustic radiation force signal, an acoustic radiation force transducer is configured to emit acoustic radiation force signals into the ROI region of the blood vessel. Subsequently, the acoustic radiation force echo signal corresponding to the acoustic radiation force signal is acquired by the angiography transducer.

[0015] Based on the acquired acoustic radiation force echo signal, the amplitude of the acoustic radiation force subharmonic under the current acoustic radiation force is determined.

[0016] When the acoustic radiation force transducer emits an acoustic radiation force signal towards the vascular ROI region, the angiography transducer area synchronously emits an angiography excitation signal towards the vascular ROI region.

[0017] When the contrast transducer emits a contrast excitation signal, the sound pressure of the contrast excitation signal is configured to the optimal incident sound pressure.

[0018] After the acoustic radiation force signal is applied to the ROI region of the blood vessel, the echo signal reflected by the angiography excitation signal through the ROI region of the blood vessel is collected to form the acoustic radiation force echo signal.

[0019] When acquiring the amplitude of the pressure measurement subharmonic, the acoustic radiation force transducer is turned off, and the angiography transducer is configured to emit angiography excitation signals to the vascular ROI region. The angiography excitation echo signals are collected by the angiography transducer, and the amplitude of the pressure measurement subharmonic is generated based on the collected angiography excitation echo signals.

[0020] When configuring the signal frequency of the acoustic radiation force signal, we have:

[0021]

[0022] Where P0 is the sound pressure of the acoustic radiation force signal, h is the amplitude reduction factor, g is the attenuation factor of the vascular ROI region, and f is the signal frequency of the acoustic radiation force signal. sh The subharmonic frequency of the voltage excitation echo signal is measured.

[0023] When determining the attenuation factor g of the vascular ROI region, we have:

[0024]

[0025] Among them, P sh To generate the subharmonic amplitude of the corresponding stationary point on the measured curve based on the vascular ROI region, P sh0 This represents the subharmonic amplitude at the corresponding stagnation point on the standard curve.

[0026] When generating the measured curve, reference excitation sound signals with different incident sound pressures are emitted into the vascular ROI region, and the corresponding subharmonic amplitude values ​​under each reference excitation sound signal are obtained, so as to generate the measured curve based on the excitation sound signal and the corresponding subharmonic amplitude values.

[0027] When generating the standard curve, an in vitro vascular phantom corresponding to the vascular ROI region is provided, and reference excitation sound signals at different sound pressures are emitted to the in vitro vascular phantom. The subharmonic amplitude value corresponding to each excitation sound signal is obtained, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude value.

[0028] The sound pressure P0 of the acoustic radiation force signal is 2.67 kPa to 13.33 kPa.

[0029] Before transmitting a reference excitation acoustic signal to the in vitro vascular phantom, a microbubble solution is injected into the in vitro vascular phantom, and degassed water is filled between the in vitro vascular phantom and the contrast ultrasound transducer.

[0030] When transmitting the reference excitation sound signal, the negative peak value of the sound pressure of the reference excitation sound signal is configured to gradually increase from 10 kPa to 1 MPa pulse sound signal. The subharmonic amplitude values ​​under different sound pressures are collected and calculated respectively, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude values.

[0031] Determining the optimal incident sound pressure includes:

[0032] The angiography transducer is configured to emit reference excitation acoustic signals with different incident sound pressures to the vascular ROI region, and the corresponding subharmonic amplitude value under each reference excitation acoustic signal is obtained;

[0033] Based on the reference excitation acoustic signal and the corresponding subharmonic amplitude, a reference excitation acoustic signal-subharmonic amplitude curve is generated.

[0034] Based on the amplitude curve of the reference excitation acoustic signal-subharmonic, the corresponding optimal incident sound pressure is determined analytically, wherein the optimal incident sound pressure is the sound pressure corresponding to the inflection point of the amplitude curve of the reference excitation acoustic signal-subharmonic.

[0035] After the contrast transducer acquires the acoustic radiation force echo signal and the contrast excitation echo signal, it performs subharmonic frequency band filtering on the acoustic radiation force echo signal and the contrast excitation echo signal respectively, and generates the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude respectively after filtering.

[0036] An ultrasonic blood pressure measurement system based on acoustic radiation force includes an angiography transducer, an acoustic radiation force transducer, and a measurement processor, wherein...

[0037] For any vascular ROI region, the angiography transducer, acoustic radiation force transducer, and measurement processor perform ultrasound blood pressure measurement based on the ultrasound blood pressure measurement method described above, and determine the blood pressure value of the vascular ROI region.

[0038] Advantages of this invention: When constructing the pressure measurement equation, the pressure measurement sensitivity A and the pressure intercept B within the equation are calculated using the optimal acoustic pressure ROI harmonic amplitude-time curve and the low-frequency acoustic radiation force ROI harmonic amplitude-time curve. The low-frequency acoustic radiation force ROI harmonic amplitude-time curve can transmit acoustic radiation force signals to the vascular ROI region through an acoustic radiation force transducer and collect the corresponding acoustic radiation force echo signals. That is, when calculating the pressure measurement sensitivity A and the pressure intercept B, the low-frequency acoustic radiation force ROI harmonic amplitude-time curve replaces the existing technology of measuring blood pressure in blood vessels through invasive pressure guidewires. This enables non-invasive blood pressure measurement using ultrasonic microbubble harmonics, improving the convenience and operability of blood pressure measurement. Attached Figure Description

[0039] Figure 1 This is a schematic flowchart of one embodiment of the ultrasonic blood pressure measurement of the present invention.

[0040] Figure 2 This is a schematic diagram of an embodiment of the present invention for solving the pressure measurement sensitivity A and the pressure measurement intercept B within the pressure measurement equation.

[0041] Figure 3 This is a schematic diagram of an embodiment of the present invention that uses an imaging transducer and an acoustic radiation force transducer to perform ultrasonic blood pressure measurement.

[0042] Figure 4 This is a schematic diagram of an embodiment of the received signal spectrum of the imaging transducer of the present invention.

[0043] Figure 5 This is a schematic diagram of one embodiment of the measured curve and standard curve of the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to specific accompanying drawings and embodiments.

[0045] As explained above, existing technologies for ultrasound blood pressure measurement require the use of invasive pressure guidewires to measure the blood pressure-time curve within the blood vessel in order to calculate the pressure sensitivity A and the pressure intercept B. Furthermore, the calculated pressure sensitivity A and pressure intercept B are easily affected by the sound pressure when the sound signal reaches the microbubble. Even if the ultrasound parameters are consistent, the intensity of the sound signal reaching different individuals, organs, and blood vessels at different depths is unknown. This means that the pressure measurement equations for these blood vessels are completely different and not interchangeable. Each pressure measurement requires re-establishing the pressure measurement equation, which is not only inefficient but also extremely difficult to perform due to the invasive blood pressure-time curve measurement.

[0046] To achieve non-invasive blood pressure measurement using ultrasonic microbubble subharmonics and improve the convenience and operability of blood pressure measurement, this invention provides an ultrasonic blood pressure measurement method based on acoustic radiation force. Specifically, the ultrasonic blood pressure measurement method includes:

[0047] For any vascular ROI region, construct a pressure measurement equation for the vascular ROI region, wherein, when constructing the pressure measurement equation, at least the pressure measurement sensitivity A and the pressure measurement intercept B within the pressure measurement equation are solved;

[0048] When calculating the pressure measurement sensitivity A and the pressure measurement intercept B, an acoustic radiation force signal is emitted at least to the vascular ROI region, and the amplitude of the acoustic radiation force subharmonic under each acoustic radiation force signal is obtained.

[0049] When emitting an acoustic radiation force signal to the vascular ROI region, at least the signal frequency of the acoustic radiation force signal is configured so that the sound pressure attenuation during the process of the acoustic radiation force signal entering the vascular ROI region matches the attenuation threshold, and the blood pressure fluctuation generated in the vascular ROI region under the acoustic radiation force signal can be observed.

[0050] Based on each acoustic radiation force signal and the corresponding acoustic radiation force subharmonic amplitude, the pressure measurement sensitivity A and pressure measurement intercept B in the pressure measurement equation are calculated.

[0051] When performing ultrasound blood pressure measurement on the vascular ROI region, the subharmonic amplitude of the pressure measurement in the vascular ROI region under the optimal incident sound pressure is obtained, and the obtained subharmonic amplitude of the pressure measurement is substituted into the pressure measurement equation to generate the blood pressure value of the vascular ROI region.

[0052] It should be noted that the ultrasound blood pressure measurement of the present invention specifically refers to measuring blood pressure in the vascular ROI region. The location of the vascular ROI region can be selected according to the actual blood pressure measurement needs. The ultrasound blood pressure measurement of the vascular ROI region is consistent with the prior art. Figure 1 The diagram illustrates a flowchart of an embodiment of ultrasound blood pressure measurement according to the present invention. As shown in the diagram, similar to the invasive ultrasound blood pressure measurement methods mentioned above in the prior art, when performing ultrasound blood pressure measurement on a vascular region of interest (ROI), a pressure measurement equation should be constructed. The constructed pressure measurement equation can adopt the aforementioned equation, such as: Psh = A*P + B. As explained above, when constructing the pressure measurement equation, the pressure sensitivity A and the pressure intercept B within the equation should be calculated. It should be understood that once the pressure sensitivity A and the pressure intercept B are calculated, the construction of the pressure measurement equation is complete.

[0053] Unlike existing technologies, this invention does not require invasive pressure wire measurement of the intravascular blood pressure-time curve when calculating the pressure sensitivity A and the pressure intercept B. However, it should at least emit an acoustic radiation force signal into the vascular ROI region and obtain the acoustic radiation force subharmonic amplitude value under each acoustic radiation force signal. It is understood that this invention uses the acoustic radiation force signal and the acoustic radiation force subharmonic amplitude value under each acoustic radiation force signal to replace the intravascular blood pressure-time curve measured by invasive pressure wire in the prior art when calculating the pressure sensitivity A and the pressure intercept B.

[0054] In practical implementation, after obtaining the amplitude of the subharmonic of the acoustic radiation force under each acoustic radiation force signal, the calculation and processing can be performed using methods commonly used in existing technologies, such as... Figure 2 The diagram illustrates one embodiment of the solution process using linear fitting. Specifically, the purpose of the solution process is to determine the pressure sensitivity A and the pressure intercept B within the pressure measurement equation. The method and process of using linear fitting for the solution process will be illustrated below.

[0055] As can be seen from the above description, when obtaining the amplitude of the subharmonic of the acoustic radiation force, an acoustic radiation force signal should be emitted towards the ROI region of the blood vessel, and the amplitude of the subharmonic of the generated radiation force under the acoustic radiation force signal should be calculated. Specifically, the emitted acoustic radiation force signal is an ultrasonic signal, and the method of emitting the acoustic radiation force signal can be consistent with the existing technology. For details, please refer to the corresponding description below.

[0056] To obtain the required subharmonic amplitude of the acoustic radiation force, the signal frequency of the acoustic radiation force signal should be configured. Specifically, the signal frequency refers to the frequency value corresponding to the acoustic radiation force signal. When configuring the signal frequency, the sound pressure attenuation during the process of the acoustic radiation force signal entering the vascular ROI region should match the attenuation threshold. Specifically, when the sound pressure attenuation matches the attenuation threshold, it means that the sound pressure attenuation during the process of the acoustic radiation force signal entering the vascular ROI region is negligible; that is, when the sound pressure attenuation matches the attenuation threshold, it means that the sound pressure attenuation during the process of the acoustic radiation force signal entering the vascular ROI region is minimal and reaches a negligible state. Therefore, the corresponding attenuation threshold can be set according to factors such as the accuracy of the ultrasound blood pressure measurement. For example, the attenuation threshold can be set to a relatively small value.

[0057] It is understandable that when an acoustic radiation force signal enters the vascular ROI region, it will change the local blood pressure in the vascular ROI region. In specific implementation, when configuring the signal frequency of the acoustic radiation force signal, it should also be possible to observe the blood pressure fluctuations generated in the ROI region under the acoustic radiation force. Therefore, the main purpose of configuring the signal frequency of the acoustic radiation force signal is to load an acoustic radiation force signal with negligible attenuation onto the vascular ROI region to change the blood pressure fluctuations in the vascular ROI region and obtain the acoustic radiation force echo signal corresponding to the blood pressure fluctuations. This can realize the measurement of the blood pressure gradient in the vascular ROI region and can replace the intravascular blood pressure time curve measured by invasive pressure guidewire in the existing technology. The method of obtaining the subharmonic amplitude of the acoustic radiation force will be explained in detail below.

[0058] As can be seen from the above description, the obtained acoustic radiation force subharmonic amplitude can reflect the blood pressure fluctuation in the vascular ROI region under the acoustic radiation force signal. Therefore, the generated acoustic radiation force subharmonic amplitude can characterize the blood pressure gradient state in the vascular ROI region, which is equivalent to the function of measuring the intravascular blood pressure time curve through the invasive pressure guidewire in the prior art. Thus, the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation can be calculated based on the acoustic radiation force signal and the acoustic radiation force subharmonic amplitude under each acoustic radiation force signal.

[0059] It should be understood that once the pressure sensitivity A and the pressure intercept B in the pressure measurement equation are obtained, the construction of the pressure measurement equation is complete. Subsequently, when performing ultrasound blood pressure measurement on the current vascular ROI region, the pressure subharmonic amplitude value of the vascular ROI region under the optimal incident sound pressure is obtained. As can be seen from the above pressure measurement equation, substituting the obtained pressure subharmonic amplitude value into the pressure measurement equation will yield the P value in the pressure measurement equation. The calculated P value is the blood pressure value of the vascular ROI region.

[0060] Since both pressure sensitivity A and pressure intercept B need to be calculated simultaneously, at least two acoustic radiation force signals should be emitted into the vascular ROI region during the calculation. The signal frequencies / sound pressures of the two acoustic radiation force signals do not need to be the same simultaneously; the specific requirement is to meet the calculation requirements for pressure sensitivity A and pressure intercept B. Preferably, multiple acoustic radiation force signals can be emitted into the vascular ROI region. By using multiple acoustic radiation force signals and their corresponding acoustic radiation force subharmonic amplitudes, methods such as linear fitting can be used to calculate pressure sensitivity A and pressure intercept B, thereby improving the calculation accuracy and reliability of pressure sensitivity A and pressure intercept B. Of course, the signal frequency of each acoustic radiation force signal should meet the above-described signal frequency correspondence.

[0061] As explained above regarding the construction of pressure measurement equations, a corresponding pressure measurement equation should be constructed for each vascular ROI region. That is, when the location of the vascular ROI region differs, the pressure measurement equation should be reconstructed using the above method. Of course, for the same vascular ROI region, only one pressure measurement equation needs to be constructed; thereafter, the equation can be directly used for ultrasound blood pressure measurement.

[0062] In one embodiment of the present invention, when acquiring the acoustic radiation force subharmonic amplitude under each acoustic radiation force signal, an acoustic radiation force transducer is configured to emit acoustic radiation force signals into the ROI region of the blood vessel. Subsequently, an angiography transducer collects the acoustic radiation force echo signals corresponding to the acoustic radiation force signals.

[0063] Based on the acquired acoustic radiation force echo signal, the amplitude of the acoustic radiation force subharmonic under the current acoustic radiation force is determined.

[0064] In order to obtain the subharmonic amplitude of acoustic radiation force for each acoustic radiation force signal, an imaging transducer and an acoustic radiation force transducer should be provided. Figure 3 The image illustrates an embodiment of the combined operation of an angiography transducer and an acoustic radiation force transducer. Specifically, the acoustic radiation force transducer can emit acoustic radiation force signals to the vascular ROI region, and the angiography transducer can collect acoustic radiation force echo signals from the vascular ROI region. Subsequently, the corresponding acoustic radiation force subharmonic amplitude can be extracted from the collected acoustic radiation force echo signals.

[0065] Since the acoustic radiation force signal is emitted through the acoustic radiation force transducer, the operating state of the transducer should be configured when setting the signal frequency of the acoustic radiation force signal to meet the above requirements. The acoustic radiation force transducer can adopt a commonly used existing form, and the method of configuring the operating state of the transducer can be consistent with existing technology, which will not be elaborated here. Furthermore, the angiography transducer can also adopt a commonly used existing form. The angiography transducer can emit ultrasound signals to the vascular ROI region and collect the echo signals reflected by the vascular ROI region.

[0066] Figure 3 In the embodiment, the direction in which the angiography transducer emits the angiography excitation signal toward the vascular ROI region is perpendicular to the direction in which the acoustic radiation force transducer emits the acoustic radiation force signal toward the vascular ROI region. Of course, during operation, the directions of the angiography excitation signal emitted by the angiography transducer and the acoustic radiation force signal emitted by the acoustic radiation force transducer can be selected as needed. For example, the acoustic radiation force transducer and the angiography transducer can be coaxial. When the acoustic radiation force transducer and the angiography transducer are coaxial, theoretically, the acoustic signals will not interfere with each other because the frequency band difference between the angiography excitation signal and the acoustic radiation force signal is too large.

[0067] In one embodiment of the present invention, when the acoustic radiation force transducer emits an acoustic radiation force signal toward the vascular ROI region, an angiography transducer is configured to simultaneously emit an angiography excitation signal toward the vascular ROI region, wherein...

[0068] When the contrast transducer emits a contrast excitation signal, the sound pressure of the contrast excitation signal is configured to the optimal incident sound pressure.

[0069] After the acoustic radiation force signal is applied to the ROI region of the blood vessel, the echo signal reflected by the angiography excitation signal through the ROI region of the blood vessel is collected to form the acoustic radiation force echo signal.

[0070] When acquiring the amplitude of the pressure measurement subharmonic, the acoustic radiation force transducer is turned off, and the angiography transducer is configured to emit angiography excitation signals to the vascular ROI region. The angiography excitation echo signals are collected by the angiography transducer, and the amplitude of the pressure measurement subharmonic is generated based on the collected angiography excitation echo signals.

[0071] In practice, before the contrast transducer emits the contrast excitation signal into the vascular ROI region, an ultrasound contrast agent should be injected into the body. Figure 2 The injection of microbubbles in this context refers to the generation of microbubbles, specifically tiny air bubbles encapsulating gas. When these microbubbles oscillate nonlinearly under an imaging excitation signal with a frequency of f0, they generate an f0 / 2 signal component, which is the subharmonic. Therefore, once the frequency of the imaging excitation signal is determined, the corresponding subharmonic can be identified, and its amplitude can be extracted, thus obtaining the subharmonic amplitude.

[0072] Figure 4 The diagram illustrates an embodiment of angiography excitation signal and its corresponding subharmonic. In the diagram, the fundamental frequency is the signal frequency of the angiography excitation signal. Therefore, after acquiring the echo signal using an angiography transducer, the corresponding subharmonic can be extracted, and its amplitude can be determined. The method and process for extracting the subharmonic and determining its amplitude are consistent with existing technologies and will not be elaborated here. Furthermore, in this invention, the terms "subharmonic" and "subharmonic amplitude" have the same meaning, and the methods for extracting and determining the subharmonic amplitude can be found herein.

[0073] To obtain the subharmonic amplitude of the acoustic radiation force, an acoustic radiation force transducer should be configured to emit an acoustic radiation force signal into the ROI region of the blood vessel. This signal acts on the microbubbles within the ROI region. Simultaneously, an angiography transducer emits an angiography excitation signal into the ROI region. Due to the influence of the acoustic radiation force signal, the reflected acoustic radiation force echo signal received by the angiography transducer reflects the effect of the signal on the microbubbles. Therefore, the acoustic radiation force echo signal of this invention primarily characterizes the effect of the acoustic radiation force signal on the microbubbles, and is not the echo signal of the original acoustic radiation force signal. As explained above, after the angiography transducer acquires the acoustic radiation force echo signal, the corresponding amplitude can be extracted using the above method, thus obtaining the subharmonic amplitude of the acoustic radiation force. It should be noted that when the angiography transducer emits the angiography excitation signal, the sound pressure of the excitation signal should be at the optimal incident sound pressure.

[0074] As explained above, during ultrasound blood pressure measurement, the amplitude of the second harmonic of the blood pressure measurement should be obtained. This amplitude is then applied to the blood pressure measurement equation. Specifically, obtaining the amplitude of the second harmonic of the blood pressure measurement generally only requires the use of an angiography transducer. At this time, the acoustic radiation force transducer should be in a non-operating state, meaning it does not emit acoustic radiation force signals towards the vascular ROI region. However, the angiography transducer should emit an angiography excitation signal towards the vascular ROI region. Subsequently, the angiography transducer collects the angiography excitation echo signal reflected from the vascular ROI region. After collecting the angiography excitation echo signal, processing it yields the angiography excitation second harmonic amplitude under the angiography excitation signal. The obtained angiography excitation second harmonic amplitude is the blood pressure measurement second harmonic amplitude.

[0075] As can be seen from the above description, when obtaining the subharmonic amplitude of pressure measurement and the subharmonic amplitude of acoustic radiation force, the sound pressure of the angiography excitation signal should be configured to be the optimal incident sound pressure. It should be noted that only when the sound pressure of the angiography excitation signal is the optimal incident sound pressure can the subharmonic amplitude and blood pressure have a linear relationship, that is, only then can the present invention be satisfied with the use of the pressure measurement equation for ultrasound blood pressure measurement.

[0076] In order to determine the optimal incident sound pressure, in one embodiment of the present invention, determining the optimal incident sound pressure includes:

[0077] The angiography transducer is configured to emit reference excitation acoustic signals with different incident sound pressures to the vascular ROI region, and the corresponding subharmonic amplitude value under each reference excitation acoustic signal is obtained;

[0078] Based on the reference excitation acoustic signal and the corresponding subharmonic amplitude, a reference excitation acoustic signal-subharmonic amplitude curve is generated.

[0079] Based on the amplitude curve of the reference excitation acoustic signal-subharmonic, the corresponding optimal incident sound pressure is determined analytically, wherein the optimal incident sound pressure is the sound pressure corresponding to the inflection point of the amplitude curve of the reference excitation acoustic signal-subharmonic.

[0080] As explained above, when using an angiography transducer to emit angiography excitation signals, the sound pressure level of the angiography excitation signal should be configured to be the optimal incident sound pressure level. Therefore, the optimal incident sound pressure level should be determined first. In one embodiment of the present invention, the angiography excitation signal refers to an ultrasound signal with the optimal incident sound pressure level. It should be noted that the signal frequency of the angiography excitation signal can be selected based on the location / type of the vascular ROI region using a default signal frequency. If the location / type of the vascular ROI region is determined, the signal frequency of the angiography excitation signal can be determined according to the technical means of this art. The method of determining the signal frequency can be consistent with existing technologies and will not be elaborated here.

[0081] The method for determining the optimal incident sound pressure can be consistent with existing technologies. One feasible embodiment is to emit reference excitation sound signals with different incident sound pressures to the vascular ROI region. The signal frequency of the reference excitation sound signal should be consistent with the signal frequency of the angiography excitation signal; the difference lies in the sound pressure levels. Therefore, the method and process of emitting the reference excitation sound signal can be consistent with existing technologies. After emitting the reference excitation sound signal, the echo signal can be acquired through an angiography transducer, and the corresponding subharmonic amplitude can be obtained using the above method. A reference excitation sound signal-subharmonic amplitude curve can be constructed using multiple reference excitation sound signals with different sound pressures and their corresponding subharmonic amplitudes.

[0082] It should be noted that the amplitude curve of the reference excitation sound signal-subharmonic generally exhibits an S-shaped growth characteristic. Therefore, by fitting the curve using the least squares method to find the incident sound pressure corresponding to the inflection point of the reference excitation sound signal-subharmonic amplitude curve, the sound pressure configuration corresponding to the inflection point is taken as the optimal incident sound pressure. The inflection point is generally the location where the subharmonic growth rate is the largest, typically found at the location of the maximum value of the first derivative of the reference excitation sound signal-subharmonic amplitude curve or the location where the second derivative is 0. Of course, other methods can also be used to determine the optimal incident sound pressure. The method and process for determining the optimal incident sound pressure can be selected as needed, and will not be illustrated here.

[0083] In order to accurately configure the signal frequency of the acoustic radiation force signal, in one embodiment of the present invention, the signal frequency of the acoustic radiation force signal is configured as follows:

[0084]

[0085] Where P0 is the sound pressure of the acoustic radiation force signal, h is the amplitude reduction factor, g is the attenuation factor of the vascular ROI region, and f is the signal frequency of the acoustic radiation force signal.sh The subharmonic frequency of the voltage excitation echo signal is measured.

[0086] In practical implementation, the sound pressure P0 of the acoustic radiation force signal ranges from 2.67 kPa to 13.33 kPa. The sound pressure P0 can be selected as needed. For example, in blood pressure measurement, the sound pressure intensity of the acoustic radiation force signal of the object being measured is determined, and the corresponding sound pressure P0 is selected. The amplitude reduction factor h can be an empirical value, such as approximately 0.45 dB. As explained above, the angiography transducer can emit an angiography excitation signal at the optimal incident sound pressure. The signal frequency of the angiography excitation signal can be determined based on factors such as the location of the vascular ROI region. Therefore, after determining the signal frequency of the angiography excitation signal, the subharmonic frequency f at the optimal incident sound pressure can be determined. sh .

[0087] In one embodiment of the present invention, when determining the attenuation factor g of the vascular ROI region, the following is obtained:

[0088]

[0089] Among them, P sh To generate the subharmonic amplitude of the corresponding stationary point on the measured curve based on the vascular ROI region, P sh0 This represents the subharmonic amplitude at the corresponding stagnation point on the standard curve.

[0090] When generating the measured curve, reference excitation sound signals with different incident sound pressures are emitted into the vascular ROI region, and the corresponding subharmonic amplitude values ​​under each reference excitation sound signal are obtained, so as to generate the measured curve based on the excitation sound signal and the corresponding subharmonic amplitude values.

[0091] When generating the standard curve, an in vitro vascular phantom corresponding to the vascular ROI region is provided, and reference excitation sound signals at different sound pressures are emitted to the in vitro vascular phantom. The subharmonic amplitude value corresponding to each excitation sound signal is obtained, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude value.

[0092] Specifically, the reference excitation sound signal can be referred to the above description of obtaining the optimal incident sound pressure, that is, the method for generating the measured curve can refer to the above-described reference excitation sound signal-subharmonic amplitude curve. In specific implementation, the standard curve can be generated in the same way as the measured curve. The difference is that when generating the standard curve, an in vitro vascular phantom should be used. The in vitro vascular phantom should include at least the organ / tissue corresponding to the vascular ROI region to effectively simulate the vascular ROI region in this invention. The in vitro vascular phantom can adopt existing commonly used forms, and can be selected according to needs.

[0093] In one embodiment of the present invention, before transmitting a reference excitation acoustic signal to the extracorporeal vascular phantom, a microbubble solution is injected into the extracorporeal vascular phantom, and degassed water is filled between the extracorporeal vascular phantom and the contrast ultrasound transducer.

[0094] When transmitting the reference excitation sound signal, the negative peak value of the sound pressure of the reference excitation sound signal is configured to gradually increase from 10 kPa to 1 MPa pulse sound signal. The subharmonic amplitude values ​​under different sound pressures are collected and calculated respectively, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude values.

[0095] Specifically, the injected microbubble solution can be the contrast agent mentioned above. When generating the standard curve, a contrast transducer should be used. Unlike generating the reference excitation acoustic signal-subharmonic amplitude curve, in this invention, when generating the standard curve and the measured curve, the negative peak value of the reference excitation acoustic signal's sound pressure can generally be gradually increased from 10 kPa to a 1 MPa pulse acoustic signal. Subsequently, the corresponding subharmonic amplitudes are collected and calculated. The method and process for collecting and calculating the subharmonic amplitudes can be referred to the above description. Afterwards, the standard curve can be generated based on the reference excitation acoustic signal and the corresponding subharmonic amplitudes. Similarly, the corresponding measured curve can be generated. It should be noted that the negative peak value can be characterized as the signal intensity of a trough of the acoustic signal half a peak away from zero.

[0096] Figure 5 The figure illustrates one embodiment of the measured curve and standard curve. In the figure, the horizontal axis represents the sound pressure of the reference excitation signal, and the vertical axis represents the subharmonic amplitude. The figure shows an embodiment where the sound pressure varies from 100 kPa to 700 kPa, and displays the corresponding subharmonic amplitudes of the measured curve and standard curve. In practical implementation, the least squares method can be used for polynomial fitting to determine the corresponding stationary points on the measured curve and standard curve. Through the corresponding stationary points on the measured curve and standard curve, the corresponding subharmonic amplitude P can be determined respectively. sh With the amplitude P of the subharmonic sh0 Subsequently, the attenuation factor g of the vascular ROI region can be calculated.

[0097] It should be noted that determining the stationary points of the measured curve and the standard curve, and determining the attenuation factor g based on the stationary points, can improve the accuracy of obtaining the attenuation factor g, thereby improving the accuracy of the signal frequency of the acoustic radiation force signal, and thus improving the accuracy and reliability of the ultrasonic blood pressure measurement of the present invention.

[0098] It is understandable that the process of generating the measured curve here is compatible with the process of determining the optimal incident sound pressure. That is, when determining the optimal incident sound pressure, the reference excitation sound signal-subharmonic amplitude curve can be used as the measured curve, or the measured curve can be generated based on the reference excitation sound signal-subharmonic amplitude curve. Since determining the optimal incident sound pressure is a necessary step for ultrasound blood pressure measurement in this invention, generating the measured curve and determining the attenuation factor g will not increase the complexity of ultrasound blood pressure measurement. In specific implementation, an external vascular phantom can be used to obtain standard curves for ROI regions of blood vessels at different locations. While determining the optimal incident sound pressure, the measured curve can be generated, thereby obtaining a precise attenuation factor g, and thus quickly configuring the signal frequency of the acoustic radiation force signal.

[0099] Furthermore, based on the requirements of ultrasound blood pressure measurement, the attenuation factor g for different vascular ROI regions can be directly determined using the above method. When measuring blood pressure in different vascular ROI regions, the corresponding attenuation factor g can be selected by giving a vascular ROI region, and the signal frequency of the acoustic radiation transducer emitting the acoustic radiation force signal can be configured accordingly. Of course, the attenuation factor g configured in this way may not be as good as the method of determining the optimal incident sound pressure. Therefore, the method of determining the optimal incident sound pressure should be preferred to determine the attenuation factor g.

[0100] In one embodiment of the present invention, after the contrast transducer acquires the acoustic radiation force echo signal and the contrast excitation echo signal, it performs subharmonic frequency band filtering on the acoustic radiation force echo signal and the contrast excitation echo signal respectively, and generates the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude respectively after filtering.

[0101] To improve the quality of acquiring the subharmonic amplitudes of acoustic radiation force and pressure measurement, subharmonic band filtering is performed on the acquired acoustic radiation force echo signal and contrast excitation echo signal, such as... Figure 2 As shown, the method and process of subharmonic filtering are consistent with existing technologies and will not be elaborated here. After subharmonic filtering, the corresponding subharmonic amplitude is determined using methods commonly used in this technical field to generate the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude, respectively.

[0102] As explained above, when transmitting acoustic radiation force signals, the sound pressure corresponding to each acoustic radiation force signal can be determined, and the amplitude of the acoustic radiation force subharmonic corresponding to each acoustic radiation force signal can also be determined. For example, for n acoustic radiation force signals, we have: Pf = [Pf1, Pf2, ..., Pfn], where Pf1, Pf2, ..., Pfn are the n acoustic radiation force signals, and the unit of the acoustic radiation force signal is mmHg; the corresponding n acoustic radiation force subharmonic amplitudes are: Pshf1 = [Pshf1, Pshf2, ..., Pshfn], where Pshf1, Pshf2, ..., Pshfn are the n acoustic radiation force subharmonic amplitudes, and the n acoustic radiation force subharmonic amplitudes correspond one-to-one with the n acoustic radiation force signals.

[0103] When the pressure measurement equation is solved using linear fitting, and the pressure measurement sensitivity A and the pressure intercept B are obtained, then:

[0104]

[0105] The above expression can be solved by least squares fitting or other methods of solving the system of equations to obtain the pressure sensitivity A and the pressure intercept B. The specific solution method and process will not be described here.

[0106] In summary, an ultrasonic blood pressure measurement system based on acoustic radiation force is obtained, including an angiography transducer, an acoustic radiation force transducer, and a measurement processor, wherein...

[0107] For any vascular ROI region, the angiography transducer, acoustic radiation force transducer, and measurement processor perform ultrasound blood pressure measurement based on the ultrasound blood pressure measurement method described above, and determine the blood pressure value of the vascular ROI region.

[0108] It should be noted that the ultrasound blood pressure measurement system should include the angiography transducer and acoustic radiation force transducer mentioned above. In addition, it should also include a measurement processor. The measurement processor can be a commonly used data processing terminal. The type of measurement processor can be selected as needed to meet the above processing requirements and obtain the blood pressure value of any vascular ROI region. The method and process for determining the blood pressure value of the vascular ROI region can be referred to the above description, and will not be repeated here.

Claims

1. A non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force, characterized in that, The non-invasive ultrasound blood pressure measurement method includes: For any vascular ROI region, construct a pressure measurement equation for the vascular ROI region, wherein, when constructing the pressure measurement equation, at least the pressure measurement sensitivity A and the pressure measurement intercept B within the pressure measurement equation are solved; The pressure measurement equation is: P sh =A*P+B, where P sh The subharmonic amplitude of the corresponding stagnation point on the measured curve is generated based on the vascular ROI region, in dB. P is the blood pressure in the blood vessel, in mmHg. The pressure measurement sensitivity A is in dB / mmHg. When calculating the pressure measurement sensitivity A and the pressure intercept B, at least two acoustic radiation force signals are emitted towards the vascular ROI region, and the amplitude of the acoustic radiation force subharmonic under each acoustic radiation force signal is obtained. When emitting an acoustic radiation force signal to the vascular ROI region, at least the signal frequency of the acoustic radiation force signal is configured so that the sound pressure attenuation during the process of the acoustic radiation force signal entering the vascular ROI region matches the attenuation threshold, and the blood pressure fluctuation generated in the vascular ROI region under the acoustic radiation force signal can be observed; based on each acoustic radiation force signal and the corresponding acoustic radiation force subharmonic amplitude, the pressure measurement sensitivity A and pressure measurement intercept B in the pressure measurement equation are calculated, wherein, during the calculation, the pressure measurement sensitivity A and pressure measurement intercept B are calculated by using a linear fitting method through multiple acoustic radiation force signals and the corresponding acoustic radiation force subharmonic amplitudes; When performing ultrasound blood pressure measurement on the vascular ROI region, the subharmonic amplitude of the pressure measurement in the vascular ROI region under the optimal incident sound pressure is obtained, and the obtained subharmonic amplitude of the pressure measurement is substituted into the pressure measurement equation to generate the blood pressure value of the vascular ROI region.

2. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to claim 1, characterized in that, When acquiring the acoustic radiation force subharmonic amplitude under each acoustic radiation force signal, an acoustic radiation force transducer is configured to emit acoustic radiation force signals into the ROI region of the blood vessel. Subsequently, the acoustic radiation force echo signal corresponding to the acoustic radiation force signal is acquired by the angiography transducer. Based on the acquired acoustic radiation force echo signal, the amplitude of the acoustic radiation force subharmonic under the current acoustic radiation force is determined.

3. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to claim 2, characterized in that, When the acoustic radiation force transducer emits an acoustic radiation force signal towards the vascular ROI region, the angiography transducer area synchronously emits an angiography excitation signal towards the vascular ROI region. When the contrast transducer emits a contrast excitation signal, the sound pressure of the contrast excitation signal is configured to the optimal incident sound pressure. After the acoustic radiation force signal is applied to the ROI region of the blood vessel, the echo signal reflected by the angiography excitation signal through the ROI region of the blood vessel is collected to form the acoustic radiation force echo signal. When acquiring the amplitude of the pressure measurement subharmonic, the acoustic radiation force transducer is turned off, and the angiography transducer is configured to emit angiography excitation signals to the vascular ROI region. The angiography excitation echo signals are collected by the angiography transducer, and the amplitude of the pressure measurement subharmonic is generated based on the collected angiography excitation echo signals.

4. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to claim 1, characterized in that, When configuring the signal frequency of the acoustic radiation force signal, we have: in, The sound pressure is the sound radiation force signal. As a reduction factor, It is an attenuation factor in the vascular ROI region. The signal frequency of the acoustic radiation force signal. The subharmonic frequency of the voltage excitation echo signal is measured.

5. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to claim 4, characterized in that, Determine the attenuation factor in the vascular ROI region Then: in, This represents the subharmonic amplitude at the corresponding stagnation point on the standard curve. When generating the measured curve, reference excitation sound signals with different incident sound pressures are emitted into the vascular ROI region, and the corresponding subharmonic amplitude values ​​under each reference excitation sound signal are obtained, so as to generate the measured curve based on the excitation sound signal and the corresponding subharmonic amplitude values. When generating the standard curve, an in vitro vascular phantom corresponding to the vascular ROI region is provided, and reference excitation sound signals at different sound pressures are emitted to the in vitro vascular phantom. The subharmonic amplitude value corresponding to each excitation sound signal is obtained, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude value.

6. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to claim 4, characterized in that, Sound pressure of acoustic radiation force signal The range is 2.67 kPa to 13.33 kPa.

7. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to claim 5, characterized in that, Before transmitting a reference excitation acoustic signal to the in vitro vascular phantom, a microbubble solution is injected into the in vitro vascular phantom, and degassed water is filled between the in vitro vascular phantom and the contrast ultrasound transducer. When transmitting the reference excitation sound signal, the negative peak value of the sound pressure of the reference excitation sound signal is configured to gradually increase from 10 kPa to 1 MPa pulse sound signal. The subharmonic amplitude values ​​under different sound pressures are collected and calculated respectively, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude values.

8. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to claim 2, characterized in that, Determining the optimal incident sound pressure includes: The angiography transducer is configured to emit reference excitation acoustic signals with different incident sound pressures to the vascular ROI region, and the corresponding subharmonic amplitude value under each reference excitation acoustic signal is obtained; Based on the reference excitation acoustic signal and the corresponding subharmonic amplitude, a reference excitation acoustic signal-subharmonic amplitude curve is generated. Based on the amplitude curve of the reference excitation acoustic signal-subharmonic, the corresponding optimal incident sound pressure is determined analytically, wherein the optimal incident sound pressure is the sound pressure corresponding to the inflection point of the amplitude curve of the reference excitation acoustic signal-subharmonic.

9. The non-invasive ultrasonic blood pressure measurement method based on acoustic radiation force according to any one of claims 2 to 8, characterized in that, After the contrast transducer acquires the acoustic radiation force echo signal and the contrast excitation echo signal, it performs subharmonic frequency band filtering on the acoustic radiation force echo signal and the contrast excitation echo signal respectively, and generates the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude respectively after filtering.

10. A non-invasive ultrasonic blood pressure measurement system based on acoustic radiation force, characterized in that, It includes an imaging transducer, an acoustic radiation force transducer, and a measurement processor, among which, For any vascular ROI region, the angiography transducer, the acoustic radiation force transducer, and the measurement processor perform ultrasound blood pressure measurement based on the non-invasive ultrasound blood pressure measurement method according to any one of claims 1 to 9, and determine the blood pressure value of the vascular ROI region.

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