Ultrasonic blood pressure measuring method and system based on acoustic radiation force

Abstract

The invention relates to an ultrasonic blood pressure measuring method and system based on acoustic radiation force. The method comprises the following steps: for any blood vessel ROI region, constructing a pressure measurement equation of the blood vessel ROI region; when the pressure measurement sensitivity A and the pressure measurement intercept B are calculated, at least transmitting acoustic radiation force signals to the blood vessel ROI, acquiring an acoustic radiation force subharmonic amplitude under each acoustic radiation force signal, and calculating the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation based on each acoustic radiation force signal and the corresponding acoustic radiation force subharmonic amplitude; when ultrasonic blood pressure measurement is conducted on the blood vessel ROI, the pressure measurement subharmonic amplitude of the blood vessel ROI under the optimal incident sound pressure is obtained, and the obtained pressure measurement subharmonic amplitude is substituted into the pressure measurement equation to generate the blood pressure value of the blood vessel ROI. According to the invention, blood pressure measurement of ultrasonic microbubble subharmonics can be realized noninvasively, and the convenience and operability of blood pressure measurement are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a measuring method and system, in particular to an ultrasonic blood pressure measuring method and system based on acoustic radiation force. BACKGROUND

[0002] The technology of blood pressure measurement using ultrasound microbubble subharmonic was first proposed by Shi et al. in 1999. They found that under certain specific acoustic parameters, the subharmonic, fundamental and second harmonic components of the microbubble scattering signal would decrease monotonously with the increase of the ambient pressure of the microbubble. In the range of 0-186 mmHg hydrostatic pressure, the decrease amplitude of the subharmonic was much larger than that of the fundamental and second harmonic.

[0003] When measuring pressure, the subharmonic response is largely dependent on the incident sound pressure, where the subharmonic response generally refers to the amplitude corresponding to the subharmonic, that is, the relationship between the subharmonic and the blood pressure is largely dependent on the incident sound pressure. The specific relationship between the subharmonic and the blood pressure is consistent with the prior art, which will not be described here. With the increase of the incident sound pressure, the subharmonic response will go through the following stages: occurrence stage, growth stage, saturation stage. In the growth stage, the subharmonic amplitude will increase rapidly with the increase of the incident sound pressure. It is found that the microbubble subharmonic signal is most sensitive to the change of the hydrostatic pressure in this stage. Therefore, under suitable acoustic parameters, a pressure measurement equation can be established between the blood pressure and the subharmonic component of the microbubble in the blood vessel: Psh=A*P+B, where Psh is the subharmonic amplitude corresponding to the ultrasonic pressure measurement of the blood vessel, unit: dB, P is the blood pressure in the blood vessel, unit: mmHg, the absolute value of A is the pressure measurement sensitivity, unit: dB / mmHg; B is the pressure measurement intercept.

[0004] When measuring the pressure in the blood vessel as described above, the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation need to be solved. Generally, when solving the pressure measurement sensitivity A and the pressure measurement intercept B, the gold standard is used, such as combining the accurate blood pressure measured by the invasive pressure wire with the subharmonic amplitude of the microbubble in the blood vessel collected synchronously under ultrasonic excitation. In theory, at least two sets of accurate blood pressure and corresponding subharmonic values can be used to solve the pressure measurement sensitivity A and the pressure measurement intercept B.

[0005] It can be understood that when the pressure measurement sensitivity A and the pressure measurement intercept B are calculated in the above-mentioned manner, the operation process obviously violates the original intention of non-invasive ultrasonic pressure measurement, and compared with the traditional technology of invasive intravascular pressure measurement by pressure wire alone, there is not enough application scenario advantage.

[0006] In summary, in the practical application of blood pressure measurement using ultrasound microbubble subharmonic waves, in order to ensure the non-invasive of the pressure measurement process, the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation cannot be determined, that is, the blood pressure gradient cannot be qualitatively judged only by the height of the subharmonic value. SUMMARY

[0007] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide an ultrasound blood pressure measurement method and system based on acoustic radiation force, which can non-invasively measure the blood pressure of ultrasound microbubble subharmonic waves and improve the convenience and operability of blood pressure measurement.

[0008] According to the technical scheme provided by the present application, an ultrasound blood pressure measurement method based on acoustic radiation force, the ultrasound blood pressure measurement method comprises:

[0009] For any blood vessel ROI region, a pressure measurement equation of the blood vessel ROI region is constructed, wherein when constructing the pressure measurement equation, at least the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation are solved;

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

[0011] When emitting the acoustic radiation force signal to the blood vessel ROI region, at least the signal frequency of the acoustic radiation force signal is configured to match the acoustic pressure attenuation and the attenuation threshold in the process of the acoustic radiation force signal entering the blood vessel ROI region, and the blood pressure fluctuation generated by the blood vessel 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 the pressure measurement intercept B in the pressure measurement equation are solved;

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

[0014] When obtaining the acoustic radiation force subharmonic amplitude under each acoustic radiation force signal, the acoustic radiation force transducer is configured to emit the acoustic radiation force signal into the blood vessel ROI region, and then the contrast transducer acquires the acoustic radiation force echo signal corresponding to the acoustic radiation force signal;

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

[0016] When the acoustic radiation force transducer emits the acoustic radiation force signal to the blood vessel ROI region, the contrast transducer region is configured to emit the contrast excitation signal to the blood vessel ROI region synchronously, wherein,

[0017] When the contrast transducer emits the contrast excitation signal, the acoustic pressure of the contrast excitation signal is configured as an optimal incident acoustic pressure;

[0018] After the acoustic radiation force signal acts on the blood vessel ROI region, the echo signal reflected by the contrast excitation signal through the blood vessel ROI region is collected to form an acoustic radiation force echo signal;

[0019] When the pressure measurement sub-harmonic amplitude is obtained, the acoustic radiation force transducer is turned off, the contrast transducer is configured to emit the contrast excitation signal to the blood vessel ROI region, and the contrast excitation echo signal is collected through the contrast transducer, and the pressure measurement sub-harmonic amplitude is generated based on the collected contrast excitation echo signal.

[0020] When the signal frequency of the acoustic radiation force signal is configured, there are:

[0021]

[0022] Wherein, P0 is the acoustic pressure of the acoustic radiation force signal, h is the amplitude reduction factor, g is the attenuation factor of the blood vessel ROI region, f is the signal frequency of the acoustic radiation force signal, f sh is the sub-harmonic frequency of the pressure measurement excitation echo signal.

[0023] When the attenuation factor g of the blood vessel ROI region is determined, there are:

[0024]

[0025] Wherein, P sh is the sub-harmonic amplitude of the corresponding stationary point on the measured curve generated based on the blood vessel ROI region, P sh0 is the sub-harmonic amplitude of the corresponding stationary point on the standard curve;

[0026] When the measured curve is generated, reference excitation sound signals of different incident acoustic pressures are emitted to the blood vessel ROI region, and corresponding sub-harmonic amplitudes under each reference excitation sound signal are obtained, so as to generate the measured curve based on the excitation sound signal and the corresponding sub-harmonic amplitude;

[0027] When the standard curve is generated, a blood vessel phantom corresponding to the blood vessel ROI region is provided, and reference excitation sound signals of different acoustic pressures are emitted to the blood vessel phantom, and corresponding sub-harmonic amplitudes under each excitation sound signal are obtained, so as to generate the standard curve based on the reference excitation sound signal and the corresponding sub-harmonic amplitude.

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

[0029] Before emitting the reference excitation sound signal to the extracorporeal blood vessel phantom, a microbubble solution is injected into the extracorporeal blood vessel phantom, and the extracorporeal blood vessel phantom is filled with degassed water between the extracorporeal blood vessel phantom and the contrast ultrasonic transducer;

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

[0031] When the optimal incident sound pressure is determined, it includes:

[0032] The contrast transducer emits reference excitation sound signals of different incident sound pressures to the blood vessel ROI area, and obtains the corresponding subharmonic amplitude under each reference excitation sound signal;

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

[0034] Based on the reference excitation sound signal-subharmonic amplitude curve, 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 reference excitation sound signal-subharmonic amplitude curve.

[0035] After the contrast transducer collects the acoustic radiation force echo signal and the contrast excitation echo signal, the acoustic radiation force echo signal and the contrast excitation echo signal are respectively filtered in the subharmonic frequency band, and the acoustic radiation force subharmonic amplitude and the pressure measuring subharmonic amplitude are respectively generated after filtering.

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

[0037] For any blood vessel ROI area, the contrast transducer, the acoustic radiation force transducer and the measurement processor perform ultrasonic blood pressure measurement based on the above-mentioned ultrasonic blood pressure measurement method, and determine the blood pressure value of the blood vessel ROI area.

[0038] The advantages of the present application: when constructing the pressure measurement equation, the optimal sound pressure ROI subharmonic amplitude time curve and the low-frequency acoustic radiation force ROI subharmonic amplitude time curve are used to solve the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation, and the low-frequency acoustic radiation force ROI subharmonic amplitude time curve can be generated by emitting an acoustic radiation force signal from the acoustic radiation force transducer to the blood vessel ROI area and collecting the corresponding acoustic radiation force echo signal, that is, when solving the pressure measurement sensitivity A and the pressure measurement intercept B, the low-frequency acoustic radiation force ROI subharmonic amplitude time curve is used to replace the blood pressure time curve measured by the invasive pressure guide wire in the prior art, so that the blood pressure measurement of the ultrasonic microbubble subharmonic can be realized non-invasively, and the convenience and operability of blood pressure measurement are improved. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is an embodiment flow diagram of the present application for ultrasonic blood pressure measurement.

[0040] Figure 2 It is an embodiment flow diagram of the present application for solving the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation.

[0041] Figure 3 It is an embodiment diagram of the present application for ultrasonic blood pressure measurement by using the contrast transducer and the acoustic radiation force transducer.

[0042] Figure 4 It is an embodiment diagram of the present application for the signal spectrum received by the contrast transducer.

[0043] Figure 5 It is an embodiment diagram of the present application for the actual curve and the standard curve. DETAILED DESCRIPTION

[0044] The present application will be further described below in combination with specific drawings and embodiments.

[0045] As can be seen from the above description, when the prior art performs ultrasonic blood pressure measurement, an invasive pressure guide wire is needed to measure the blood pressure time curve in the blood vessel, so as to solve the pressure measurement sensitivity A and the pressure measurement intercept B, and the pressure measurement sensitivity A and the pressure measurement intercept B obtained by solving are easily affected by the sound pressure when the sound signal reaches the microbubble, that is, even if the sound parameters of the ultrasound are consistent, the intensity of the sound signal reaching the blood vessel in different human bodies, different organs and different depths is unknown, which means that the pressure measurement equations of these blood vessels are completely different and not mutually usable, and each pressure measurement needs to re-establish the pressure measurement equation, which is not only low in efficiency, but also has great difficulty in actual operation due to the need for invasive blood pressure time curve measurement.

[0046] In order to realize non-invasive ultrasound microbubble subharmonic blood pressure measurement, improve the convenience and operability of blood pressure measurement, the application provides an ultrasound blood pressure measurement method based on acoustic radiation force, and specifically, the ultrasound blood pressure measurement method comprises the following steps:

[0047] For any blood vessel ROI region, a pressure measurement equation of the blood vessel ROI region is constructed, wherein when the pressure measurement equation is constructed, at least the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation are solved;

[0048] When the pressure measurement sensitivity A and the pressure measurement intercept B are solved, at least the acoustic radiation force signal is emitted to the blood vessel ROI region, and the acoustic radiation force subharmonic amplitude under each acoustic radiation force signal is obtained,

[0049] When the acoustic radiation force signal is emitted to the blood vessel ROI region, at least the signal frequency of the acoustic radiation force signal is configured, so that the acoustic pressure attenuation in the process of the acoustic radiation force signal entering the blood vessel ROI region matches the attenuation threshold, and the blood pressure fluctuation generated by the blood vessel 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 the pressure measurement intercept B in the pressure measurement equation are solved;

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

[0052] It should be noted that the ultrasound blood pressure measurement of the application specifically refers to blood pressure measurement on the blood vessel ROI region, and the position of the blood vessel ROI region can be selected according to the actual blood pressure measurement requirement. The ultrasound blood pressure measurement on the blood vessel ROI region is consistent with the prior art. Figure 1 An embodiment flowchart for performing ultrasound blood pressure measurement by the application is shown in FIG. 1, and as shown in the figure, similar to the invasive ultrasound blood pressure measurement in the prior art, when the ultrasound blood pressure measurement is performed on the blood vessel ROI region, the pressure measurement equation should be constructed, and the constructed pressure measurement equation can be the pressure measurement equation mentioned above, such as the constructed pressure measurement equation Psh=A*P+B. As described above, when the pressure measurement equation is constructed, the pressure measurement sensitivity A and the pressure measurement intercept B in the pressure measurement equation should be solved, and it should be understood that when the pressure measurement sensitivity A and the pressure measurement intercept B are solved, the construction of the pressure measurement equation is completed.

[0053] Unlike the prior art, the present application does not need to use an invasive pressure guide wire to measure the blood pressure time curve in the blood vessel when calculating the pressure sensing sensitivity A and the pressure intercept B, but should at least emit an acoustic radiation force signal to the blood vessel ROI region and obtain the acoustic radiation force sub-harmonic amplitude under each acoustic radiation force signal. It can be understood that the present application uses the acoustic radiation force signal and the acoustic radiation force sub-harmonic amplitude under each acoustic radiation force signal to replace the blood pressure time curve in the blood vessel measured by the invasive pressure guide wire in the prior art when calculating the pressure sensing sensitivity A and the pressure intercept B.

[0054] In specific implementation, after obtaining the acoustic radiation force sub-harmonic amplitude under each acoustic radiation force signal, the commonly used manner in the prior art can be used for calculation and processing, such as Figure 2 An embodiment that can be calculated and processed by linear fitting is shown in the above, specifically, the purpose of calculation and processing is to calculate and determine the pressure sensing sensitivity A and the pressure intercept B in the pressure sensing equation, the manner and process of calculation and processing by linear fitting will be illustrated below.

[0055] As can be known from the above description, when obtaining the acoustic radiation force sub-harmonic amplitude, the acoustic radiation force signal should be emitted to the blood vessel ROI region, and the acoustic radiation force sub-harmonic amplitude under the acoustic radiation force signal should be calculated and obtained, specifically, the emitted acoustic radiation force signal is an ultrasonic signal, and the manner of emitting the acoustic radiation force signal can be consistent with the prior art, and specific reference can be made to the corresponding description below.

[0056] In order to obtain the required acoustic radiation force sub-harmonic amplitude, the signal frequency of the acoustic radiation force signal should be configured, wherein the signal frequency specifically refers to the frequency value corresponding to the acoustic radiation force signal, when configuring the signal frequency of the acoustic radiation force signal, the acoustic pressure attenuation in the process of the acoustic radiation force signal entering the blood vessel ROI region should be matched with the attenuation threshold, specifically, when the acoustic pressure attenuation is matched with the attenuation threshold, specifically, the acoustic pressure attenuation in the process of the acoustic radiation force signal entering the blood vessel ROI region can be ignored; that is, when the acoustic pressure attenuation is matched with the attenuation threshold, specifically, the acoustic pressure attenuation in the process of the acoustic radiation force signal entering the blood vessel ROI region is less and reaches a negligible state, thereby the corresponding attenuation threshold can be set according to the accuracy of ultrasonic blood pressure measurement and the like, such as the attenuation threshold can be set to a smaller value.

[0057] It can be understood that when the acoustic radiation force signal enters the blood vessel ROI area, the local blood pressure of the blood vessel ROI area will change. In actual implementation, when configuring the signal frequency of the acoustic radiation force signal, the blood pressure fluctuation of the ROI area generated under the acoustic radiation force should also be observed. Therefore, when configuring the signal frequency of the acoustic radiation force signal, the main purpose is to load an acoustic radiation force signal with negligible attenuation to the blood vessel ROI area to change the blood pressure fluctuation of the blood vessel ROI area, and to obtain the acoustic radiation force echo signal corresponding to the blood pressure fluctuation. In this way, the blood pressure gradient of the blood vessel ROI area can be measured, and the intravascular blood pressure time curve measured by the invasive pressure guide wire in the prior art can be replaced. The method of obtaining the acoustic radiation force subharmonic amplitude will be described 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 of the blood vessel ROI area under the acoustic radiation force signal. Therefore, the generated acoustic radiation force subharmonic amplitude can represent the blood pressure gradient state of the blood vessel ROI area, which is equivalent to the effect of measuring the intravascular blood pressure time curve by the invasive pressure guide wire in the prior art. Thus, the pressure sensing sensitivity A and the pressure sensing intercept B in the pressure sensing 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 when the pressure sensing sensitivity A and the pressure sensing intercept B in the pressure sensing equation are solved, the construction of the pressure sensing equation is completed. Thereafter, when measuring the ultrasonic blood pressure of the current blood vessel ROI area, the pressure sensing subharmonic amplitude of the blood vessel ROI area under the optimal incident sound pressure is obtained. As can be seen from the above pressure sensing equation, the obtained pressure sensing subharmonic amplitude is substituted into the pressure sensing equation, and the P value in the pressure sensing equation is obtained. The calculated P value is the blood pressure value of the blood vessel ROI area.

[0060] Since the pressure sensing sensitivity A and the pressure sensing intercept B need to be calculated simultaneously, at least two acoustic radiation force signals should be transmitted to the blood vessel ROI area during calculation. The signal frequency / acoustic pressure of the two acoustic radiation force signals can be different, and the specific condition is that it can meet the requirement of calculating the pressure sensing sensitivity A and the pressure sensing intercept B. Preferably, a plurality of acoustic radiation force signals can be transmitted to the blood vessel ROI area. The pressure sensing sensitivity A and the pressure sensing intercept B can be calculated by linear fitting and other methods using the plurality of acoustic radiation force signals and the corresponding acoustic radiation force subharmonic amplitudes, so as to improve the calculation accuracy and reliability of the pressure sensing sensitivity A and the pressure sensing intercept B. Of course, the signal frequency of each acoustic radiation force signal should meet the above description of the signal frequency.

[0061] From the above description of constructing the pressure measurement equation, it is known that a corresponding pressure measurement equation should be constructed for each blood vessel ROI region, that is, when the position and the like of the blood vessel ROI region are different, the pressure measurement equation should be re-constructed in the above manner. Of course, for the same blood vessel ROI region, the pressure measurement equation can be constructed only once, and thereafter, the ultrasonic blood pressure measurement can be directly performed by using the pressure measurement equation.

[0062] In an embodiment of the present application, when the amplitude of the acoustic radiation force sub-harmonic under each acoustic radiation force signal is obtained, the acoustic radiation force transducer is configured to emit the acoustic radiation force signal into the blood vessel ROI region, and then the contrast transducer is configured to collect the acoustic radiation force echo signal corresponding to the acoustic radiation force signal.

[0063] Based on the obtained acoustic radiation force echo signal, the amplitude of the acoustic radiation force sub-harmonic under the current acoustic radiation force is determined.

[0064] In order to obtain the amplitude of the acoustic radiation force sub-harmonic under each acoustic radiation force signal, the contrast transducer and the acoustic radiation force transducer should be provided, Figure 3 An embodiment of the cooperation of the contrast transducer and the acoustic radiation force transducer is shown in the figure, specifically, the acoustic radiation force transducer can emit the acoustic radiation force signal into the blood vessel ROI region, the contrast transducer can collect the acoustic radiation force echo signal of the blood vessel ROI region, and then the amplitude of the corresponding acoustic radiation force sub-harmonic can be extracted from the collected acoustic radiation force echo signal.

[0065] Since the acoustic radiation force signal is emitted by the acoustic radiation force transducer, when the signal frequency of the acoustic radiation force signal is configured, the working state of the acoustic radiation force transducer should be configured so that the signal frequency of the acoustic radiation force signal emitted by the acoustic radiation force transducer meets the above requirements. The acoustic radiation force transducer can adopt the existing common form, and the configuration of the working state of the acoustic radiation force transducer can be consistent with the existing technology, which will not be described here. In addition, the contrast transducer can also adopt the existing common form, and the contrast transducer can emit the ultrasonic signal to the blood vessel ROI region and collect the echo signal reflected by the blood vessel ROI region.

[0066] Figure 3 In the embodiment of the figure, the direction of the contrast excitation signal emitted by the contrast transducer to the blood vessel ROI region is perpendicular to the direction of the acoustic radiation force signal emitted by the acoustic radiation force transducer to the blood vessel ROI region. Of course, during operation, the direction of the contrast excitation signal emitted by the contrast transducer and the direction of 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 contrast transducer can be coaxial. When the acoustic radiation force transducer and the contrast transducer are coaxial, since the frequency band difference between the contrast excitation signal and the acoustic radiation force signal is too large, theoretically, the acoustic signals do not interfere with each other.

[0067] In one embodiment of the present application, when the acoustic radiation force transducer emits an acoustic radiation force signal to the blood vessel ROI region, the contrast transducer region is configured to emit a contrast excitation signal to the blood vessel ROI region, wherein,

[0068] When the contrast transducer emits the contrast excitation signal, the acoustic pressure of the contrast excitation signal is configured as an optimal incident acoustic pressure;

[0069] After the acoustic radiation force signal acts on the blood vessel ROI region, echo signals reflected by the contrast excitation signal through the blood vessel ROI region are collected to form an acoustic radiation force echo signal;

[0070] When obtaining the pressure measurement sub-harmonic amplitude, the acoustic radiation force transducer is turned off, the contrast transducer is configured to emit a contrast excitation signal to the blood vessel ROI region, and a contrast excitation echo signal is collected through the contrast transducer, and the pressure measurement sub-harmonic amplitude is generated based on the collected contrast excitation echo signal.

[0071] In specific implementation, before the contrast transducer emits a contrast excitation signal to the blood vessel ROI region, an ultrasound contrast agent should be injected into the body, Figure 2 The injection of microbubbles in the above formula is to generate microbubbles, and the microbubbles specifically refer to small gas bubbles wrapped with gas. When the microbubbles are subjected to nonlinear oscillation under a contrast excitation signal with a signal frequency f0, an f0 / 2 signal component is generated, and the generated f0 / 2 signal component is a sub-harmonic. Therefore, after the signal frequency of the contrast excitation signal is determined, the corresponding sub-harmonic can be determined, and then the amplitude corresponding to the sub-harmonic can be extracted, so that the sub-harmonic amplitude can be obtained.

[0072] Figure 4 An embodiment of the contrast excitation signal and the sub-harmonic corresponding to the contrast excitation signal is shown in the above formula. In the figure, the fundamental wave is the signal frequency of the contrast excitation signal. Therefore, after the echo signal is collected by the contrast transducer, the corresponding sub-harmonic can be extracted, and then the corresponding sub-harmonic amplitude can be determined. The way and process of extracting the sub-harmonic and determining the sub-harmonic amplitude can be consistent with the prior art, and will not be described here. In addition, the sub-harmonic and the sub-harmonic amplitude in the present application have the same meaning, and the way of extracting the sub-harmonic and determining the sub-harmonic amplitude can be referred to the description herein.

[0073] In order to obtain the acoustic radiation force sub-harmonic amplitude, the acoustic radiation force transducer should be configured to emit the acoustic radiation force signal to the blood vessel ROI area, the acoustic radiation force signal acts on the microbubbles in the blood vessel ROI area, the contrast transducer synchronously emits the contrast excitation signal to the blood vessel ROI area, the microbubbles are affected by the acoustic radiation force signal, and the acoustic radiation force echo signal reflected and received by the contrast transducer reflects the effect of the acoustic radiation force signal on the microbubbles, that is, the acoustic radiation force echo signal of the application mainly characterizes the effect of the acoustic radiation force signal on the microbubbles, and is not the echo signal of the acoustic radiation force signal. As can be seen from the above description, after the contrast transducer collects the acoustic radiation force echo signal, the corresponding amplitude can be extracted according to the above method, that is, the acoustic radiation force sub-harmonic amplitude can be obtained. It should be noted that when the contrast transducer emits the contrast excitation signal, the sound pressure of the contrast excitation signal should be the optimal incident sound pressure.

[0074] As can be seen from the above description, when measuring the blood pressure by ultrasound, the pressure measurement sub-harmonic amplitude should be obtained, and then the pressure measurement sub-harmonic amplitude is loaded into the pressure measurement equation. Specifically, when obtaining the pressure measurement sub-harmonic amplitude, generally only the contrast transducer is needed, at this time, the acoustic radiation force transducer should be in a non-working state, that is, the acoustic radiation force transducer does not emit the acoustic radiation force signal to the blood vessel ROI area, but the contrast transducer should emit the contrast excitation signal to the blood vessel ROI area. After that, the contrast transducer collects the contrast excitation echo signal reflected by the blood vessel ROI area, and after collecting the contrast excitation echo signal, the contrast excitation echo signal is processed to obtain the contrast excitation sub-harmonic amplitude under the contrast excitation signal. The obtained contrast excitation sub-harmonic amplitude is the pressure measurement sub-harmonic amplitude.

[0075] As can be seen from the above description, when obtaining the pressure measurement sub-harmonic amplitude and the acoustic radiation force sub-harmonic amplitude, the sound pressure of the contrast excitation signal should be the optimal incident sound pressure. It should be noted that when the sound pressure of the contrast excitation signal is the optimal incident sound pressure, the sub-harmonic amplitude and the blood pressure are in a linear relationship, that is, the application meets the requirement of measuring the blood pressure by ultrasound by using the pressure measurement equation.

[0076] In order to determine the optimal incident sound pressure, in one embodiment of the application, when determining the optimal incident sound pressure, the following steps are included:

[0077] The contrast transducer is configured to emit reference excitation sound signals with different incident sound pressures to the blood vessel ROI area, and the corresponding sub-harmonic amplitudes under each reference excitation sound signal are obtained.

[0078] Based on the reference excitation sound signal and the corresponding sub-harmonic amplitude, a reference excitation sound signal-sub-harmonic amplitude curve is generated.

[0079] Based on the reference excitation sound signal-subharmonic amplitude curve, 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 reference excitation sound signal-subharmonic amplitude curve.

[0080] As can be seen from the above description, when the contrast transducer transmits the contrast excitation signal, the sound pressure of the contrast excitation signal should be configured and the sound pressure of the contrast excitation signal should be the optimal incident sound pressure. Therefore, the optimal incident sound pressure should be determined first. In an embodiment of the present application, the contrast excitation signal refers to an ultrasonic signal with a sound pressure of the optimal incident sound pressure. It should be noted that the signal frequency of the contrast excitation signal can be selected according to the position / type of the blood vessel ROI region. For example, after determining the position / type of the blood vessel ROI region, the signal frequency of the contrast excitation signal can be determined according to the technical means in the technical field. The method for determining the signal frequency can be consistent with the prior art, which will not be described here.

[0081] The method for determining the optimal incident sound pressure can be consistent with the prior art. In one feasible embodiment, reference excitation sound signals with different incident sound pressures are transmitted to the blood vessel ROI region. The signal frequency of the reference excitation sound signal should be consistent with that of the contrast excitation signal, except that the sound pressures of the two signals can be different. Therefore, the method and process for transmitting the reference excitation sound signal can be consistent with the prior art. After transmitting the reference excitation sound signal, the echo signal can be collected by the contrast transducer, and the corresponding subharmonic amplitude can be obtained by using the above method. The reference excitation sound signal-subharmonic amplitude curve can be constructed by using the reference excitation sound signals with different sound pressures and the corresponding subharmonic amplitudes.

[0082] It should be noted that the reference excitation sound signal-subharmonic amplitude curve generally has an S-shaped growth characteristic. Therefore, the incident sound pressure corresponding to the inflection point of the reference excitation sound signal-subharmonic amplitude curve is found by least squares fitting, and the sound pressure corresponding to the inflection point is configured as the optimal incident sound pressure. The inflection point is generally the position point with the maximum subharmonic speed. Generally, the position point with the maximum first derivative or the position point with the second derivative of 0 of the reference excitation sound signal-subharmonic amplitude curve is used. 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, which will not be described here.

[0083] In order to accurately configure the signal frequency of the acoustic radiation force signal, in an embodiment of the present application, when the signal frequency of the acoustic radiation force signal is configured, the following formula is used:

[0084]

[0085] wherein P0 is the sound pressure of the acoustic radiation force signal, h is the amplitude reduction factor, g is the attenuation factor of the blood vessel ROI region, f is the signal frequency of the acoustic radiation force signal, and fsh The subharmonic frequency of the pressure measurement excitation echo signal is determined.

[0086] In specific implementation, the acoustic pressure P0 of the acoustic radiation force signal is 2.67 kPa-13.33 kPa, and the acoustic pressure P0 of the acoustic radiation force signal can be selected as required, for example, in blood pressure measurement, the acoustic pressure intensity of the acoustic radiation force signal of the blood pressure measurement object is judged, and the corresponding acoustic pressure P0 of the acoustic radiation force signal is selected. The reduction factor h can be an empirical value, for example, about 0.45 dB. As can be known from the above description, the contrast transducer can emit a contrast excitation signal at the optimal incident acoustic pressure, and the signal frequency of the contrast excitation signal can be selected and determined according to the position of the blood vessel ROI region, and therefore, after the signal frequency of the contrast excitation signal is determined, the subharmonic frequency f sh .

[0087] In an embodiment of the present application, when the attenuation factor g of the blood vessel ROI region is determined, then:

[0088]

[0089] wherein, P sh is the subharmonic amplitude of the corresponding stationary point on the measured curve generated based on the blood vessel ROI region, and P sh0 is the subharmonic amplitude of the corresponding stationary point on the standard curve;

[0090] In generating the measured curve, reference excitation sound signals of different incident acoustic pressures are emitted to the blood vessel ROI region, and the corresponding subharmonic amplitudes 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;

[0091] In generating the standard curve, a blood vessel phantom corresponding to the blood vessel ROI region is provided, reference excitation sound signals of different acoustic pressures are emitted to the blood vessel phantom, and the corresponding subharmonic amplitudes under each excitation sound signal are obtained, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude.

[0092] Specifically, the case of the reference excitation sound signal can refer to the above description of obtaining the optimal incident acoustic pressure, that is, the way of generating the measured curve can refer to the above reference excitation sound signal-subharmonic amplitude curve. In specific implementation, the standard curve can be generated by referring to the way of generating the measured curve, and the difference is that the blood vessel phantom should be used in generating the standard curve, and the blood vessel phantom should at least include an organ / tissue corresponding to the blood vessel ROI region, so as to effectively simulate the blood vessel ROI region in the present application. The blood vessel phantom can adopt a form commonly used at present, and can be selected as required.

[0093] In one embodiment of the present application, before emitting the reference excitation acoustic signal to the extracorporeal blood vessel phantom, the microbubble solution is injected into the extracorporeal blood vessel phantom, and the extracorporeal blood vessel phantom is filled with degassed water between the extracorporeal blood vessel phantom and the contrast ultrasonic transducer.

[0094] When the reference excitation acoustic signal is emitted, the negative peak value of the sound pressure of the reference excitation acoustic signal is gradually increased from 10 kPa to 1 MPa pulse acoustic signal, and the subharmonic amplitude at different sound pressures is respectively collected and calculated, so as to generate the standard curve based on the reference excitation acoustic signal and the corresponding subharmonic amplitude.

[0095] Specifically, the injected microbubble solution can be the contrast agent mentioned above. When generating the standard curve, the contrast transducer should be used. Different from generating the reference excitation acoustic signal-subharmonic amplitude curve, in the present application, when generating the standard curve and the measured curve, the negative peak value of the sound pressure of the reference excitation acoustic signal can be generally increased from 10 kPa to 1 MPa pulse acoustic signal, and then the corresponding subharmonic amplitude is respectively collected and calculated. The way and process of collecting and calculating the subharmonic amplitude can be referred to the above description. Then, the standard curve can be generated based on the reference excitation acoustic signal and the corresponding subharmonic amplitude. Similarly, the corresponding measured curve can be generated. It should be noted that the negative peak value can be represented as the signal intensity of a wave trough of the acoustic signal being half a peak away from zero.

[0096] Figure 5 One embodiment of the measured curve and the standard curve is shown in the figure. In the figure, the horizontal coordinate is the sound pressure of the reference excitation acoustic signal, and the vertical coordinate is the subharmonic amplitude. In the figure, one embodiment of the change of the sound pressure from 100 kPa to 700 kPa is shown, and the corresponding subharmonic amplitude of the measured curve and the standard curve is shown. In specific implementation, the least square method can be used for polynomial fitting to determine the corresponding stationary points on the measured curve and the standard curve. Through the corresponding stationary points on the measured curve and the standard curve, the corresponding subharmonic amplitude P sh and the subharmonic amplitude P sh0 Then, the attenuation factor g of the blood vessel ROI region can be calculated.

[0097] It should be noted that when the stationary points of the measured curve and the standard curve are determined, and the attenuation factor g is determined based on the stationary points, the accuracy of the obtained attenuation factor g can be improved, and then the accuracy of the signal frequency of the configured acoustic radiation force signal can be improved, so that the accuracy and reliability of the ultrasonic blood pressure measurement of the present application can be improved.

[0098] It can be understood that the process of generating the measured curve here is compatible with the process of determining the optimal incident sound pressure described above, 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 the present application to measure ultrasonic blood pressure, generating the measured curve and determining the attenuation factor g will not increase the complexity of ultrasonic blood pressure measurement. In specific implementation, the standard curve of the ROI region of the blood vessel at different positions can be obtained by using an extracorporeal blood vessel phantom, and the measured curve can be generated at the same time as the optimal incident sound pressure is determined, so that the accurate attenuation factor g can be obtained, and the signal frequency of the acoustic radiation force signal can be quickly configured.

[0099] In addition, the attenuation factor g of different blood vessel ROI regions can also be directly determined according to the needs of ultrasonic blood pressure measurement in the above-mentioned manner. When measuring the blood pressure of different blood vessel ROI regions, the corresponding attenuation factor g can be selected by giving the blood vessel ROI region, and the signal frequency of the acoustic radiation force signal emitted by the acoustic radiation transducer can be configured accordingly. Of course, the attenuation factor g configured at this time may not be as good as that determined in a manner compatible with the optimal incident sound pressure, and therefore, the attenuation factor g should be preferably determined in a manner compatible with the determination of the optimal incident sound pressure.

[0100] In an embodiment of the present application, after the contrast transducer collects the acoustic radiation force echo signal and the contrast excitation echo signal, the acoustic radiation force echo signal and the contrast excitation echo signal are respectively filtered in the subharmonic frequency band, and the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude are respectively generated after filtering.

[0101] In order to improve the quality of obtaining the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude, the collected acoustic radiation force echo signal and contrast excitation echo signal are filtered in the subharmonic band, as shown in Figure 2 The way and process of subharmonic band filtering can be consistent with the prior art, which will not be described here. After subharmonic band filtering, the corresponding subharmonic amplitude is determined in a manner commonly used in the technical field, to generate the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude, respectively.

[0102] From the above description, when the acoustic radiation force signals are emitted, the corresponding acoustic pressure of each acoustic radiation force signal can be determined, and the corresponding acoustic radiation force sub-harmonic amplitude of each acoustic radiation force signal can be determined. For n acoustic radiation force signals, there are: Pf = [Pf1, Pf2, …, Pfn], where Pf1, Pf2, …, Pfn are respectively n acoustic radiation force signals, and the unit of the acoustic radiation force signal is mmHg; and the corresponding n acoustic radiation force sub-harmonic amplitudes are: Pshf1 = [Pshf1, Pshf2, …, Pshfn], where Pshf1, Pshf2, …, Pshfn are respectively n acoustic radiation force sub-harmonic amplitudes, and the n acoustic radiation force sub-harmonic amplitudes correspond to the n acoustic radiation force signals one by one.

[0103] When the linear fitting is used to solve the pressure measurement equation, and the pressure measurement sensitivity A and the pressure measurement intercept B are obtained, there are:

[0104]

[0105] For the above expression, the least square fitting or other equation solving method can be used to solve the pressure measurement sensitivity A and the pressure measurement intercept B. The specific solving method and process are not described here.

[0106] In summary, an ultrasonic blood pressure measurement system based on acoustic radiation force can be obtained, which includes a contrast transducer, an acoustic radiation force transducer, and a measurement processor, wherein,

[0107] For any blood vessel ROI region, the contrast transducer, the acoustic radiation force transducer, and the measurement processor perform ultrasonic blood pressure measurement based on the above-mentioned ultrasonic blood pressure measurement method, and determine the blood pressure value of the blood vessel ROI region.

[0108] It should be noted that the ultrasonic blood pressure measurement system should include the above-mentioned contrast transducer and acoustic radiation force transducer, and in addition, should also include a measurement processor. The measurement processor can use an existing commonly used data processing terminal. The type of the measurement processor can be selected as needed to meet the above-mentioned processing and obtain the blood pressure value of any blood vessel ROI region. The way and process of determining the blood pressure value of the blood vessel ROI region can be referred to the above description, which is not described here.

Claims

1. An acoustic radiation force based ultrasonic blood pressure measurement method, characterized in that, The ultrasonic blood pressure measurement method comprises: For any blood vessel ROI region, a pressure measurement equation of the blood vessel ROI region is constructed, wherein when the pressure measurement equation is constructed, at least a pressure measurement sensitivity A and a pressure measurement intercept B in the pressure measurement equation are solved; When the pressure measurement sensitivity A and the pressure measurement intercept B are solved, at least an acoustic radiation force signal is emitted to the blood vessel ROI region, and an acoustic radiation force subharmonic amplitude under each acoustic radiation force signal is obtained, When the acoustic radiation force signal is emitted to the blood vessel ROI region, at least a signal frequency of the acoustic radiation force signal is configured, so that an acoustic pressure attenuation in the process of the acoustic radiation force signal entering the blood vessel ROI region matches an attenuation threshold, and a blood pressure fluctuation of the blood vessel ROI region generated 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 the pressure measurement intercept B in the pressure measurement equation are solved; When the ultrasonic blood pressure measurement is performed on the blood vessel ROI region, a pressure measurement subharmonic amplitude of the blood vessel ROI region under the optimal incident acoustic pressure is obtained, and the obtained pressure measurement subharmonic amplitude is substituted into the pressure measurement equation to generate a blood pressure value of the blood vessel ROI region.

2. The acoustic radiation force based ultrasonic blood pressure measurement method of claim 1, wherein, When the acoustic radiation force subharmonic amplitude under each acoustic radiation force signal is obtained, the acoustic radiation force transducer is configured to emit the acoustic radiation force signal to the blood vessel ROI region, and then the contrast transducer acquires the acoustic radiation force echo signal corresponding to the acoustic radiation force signal; Based on the obtained acoustic radiation force echo signal, the acoustic radiation force subharmonic amplitude under the current acoustic radiation force is determined.

3. The acoustic radiation force based ultrasonic blood pressure measurement method of claim 2, wherein, When the acoustic radiation force transducer emits the acoustic radiation force signal to the blood vessel ROI region, the contrast transducer is configured to synchronously emit a contrast excitation signal to the blood vessel ROI region, wherein When the contrast transducer emits the contrast excitation signal, the acoustic pressure of the contrast excitation signal is configured as the optimal incident acoustic pressure; After the acoustic radiation force signal acts on the blood vessel ROI region, the echo signal reflected by the blood vessel ROI region to the contrast excitation signal is acquired to form the acoustic radiation force echo signal; When the pressure measurement subharmonic amplitude is obtained, the acoustic radiation force transducer is turned off, the contrast transducer is configured to emit the contrast excitation signal to the blood vessel ROI region, the contrast excitation echo signal is acquired by the contrast transducer, and the pressure measurement subharmonic amplitude is generated based on the acquired contrast excitation echo signal.

4. The acoustic radiation force based ultrasonic blood pressure measurement method of claim 1, wherein, When the signal frequency of the acoustic radiation force signal is configured, the following is obtained: wherein P0 is the sound pressure of the acoustic radiation force signal, h is a drop factor, g is an attenuation factor of the blood vessel ROI region, f is the signal frequency of the acoustic radiation force signal, f sh is the subharmonic frequency of the pressure measurement excitation echo signal.

5. The acoustic radiation force based ultrasonic blood pressure measurement method of claim 4, wherein, When the attenuation factor g of the blood vessel ROI region is determined, the following is obtained: wherein P sh is the sub-harmonic amplitude of the corresponding stationary point on the measured curve based on the blood vessel ROI region, P sh0 is the sub-harmonic amplitude of the corresponding stationary point on the standard curve; When the measured curve is generated, a reference excitation sound signal of different incident acoustic pressures is emitted to the blood vessel ROI region, and a corresponding subharmonic amplitude under each reference excitation sound signal is obtained, so as to generate the measured curve based on the excitation sound signal and the corresponding subharmonic amplitude; When the standard curve is generated, an in-vitro blood vessel phantom corresponding to the blood vessel ROI region is provided, a reference excitation sound signal of different acoustic pressures is emitted to the in-vitro blood vessel phantom, and a corresponding subharmonic amplitude under 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.

6. The acoustic radiation force based ultrasonic blood pressure measurement method of claim 4, wherein, The acoustic pressure P0 of the acoustic radiation force signal is 2.67 kPa to 13.33 kPa.

7. The acoustic radiation force based ultrasonic blood pressure measurement method of claim 5, wherein, Before emitting the reference excitation sound signal to the extracorporeal blood vessel phantom, a microbubble solution is injected into the extracorporeal blood vessel phantom, and the extracorporeal blood vessel phantom is filled with degassed water between the extracorporeal blood vessel phantom and the contrast ultrasonic transducer; When the reference excitation sound signal is emitted, the negative peak value of the sound pressure of the reference excitation sound signal is gradually increased from 10 kPa to 1 MPa pulse sound signal, and the subharmonic amplitude under different sound pressures is respectively collected and calculated, so as to generate the standard curve based on the reference excitation sound signal and the corresponding subharmonic amplitude.

8. The acoustic radiation force based ultrasonic blood pressure measurement method of claim 2, wherein, When the optimal incident sound pressure is determined, the method comprises: The contrast transducer emits reference excitation sound signals with different incident sound pressures to the blood vessel ROI region, and the corresponding subharmonic amplitude under each reference excitation sound signal is obtained; Based on the reference excitation sound signal and the corresponding subharmonic amplitude, a reference excitation sound signal-subharmonic amplitude curve is generated; Based on the reference excitation sound signal-subharmonic amplitude curve, the corresponding optimal incident sound pressure is determined, wherein the optimal incident sound pressure is the sound pressure corresponding to the inflection point of the reference excitation sound signal-subharmonic amplitude curve.

9. The acoustic radiation force based ultrasonic blood pressure measurement method according to any one of claims 2 to 8, characterized in that, After the contrast transducer collects the acoustic radiation force echo signal and the contrast excitation echo signal, the acoustic radiation force echo signal and the contrast excitation echo signal are respectively filtered in the subharmonic frequency band, and the acoustic radiation force subharmonic amplitude and the pressure measurement subharmonic amplitude are respectively generated after filtering.

10. An acoustic radiation force based ultrasonic blood pressure measurement system, characterized in that, The system comprises a contrast transducer, an acoustic radiation force transducer, and a measurement processor, wherein, For any blood vessel ROI region, the contrast transducer, the acoustic radiation force transducer, and the measurement processor perform ultrasonic blood pressure measurement based on the ultrasonic blood pressure measurement method of any one of the above claims 1-9, and determine the blood pressure value of the blood vessel ROI region.

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