WO2023097781A1 - 双频血管内超声换能器、血管壁杨氏模量计算方法和装置 - Google Patents

双频血管内超声换能器、血管壁杨氏模量计算方法和装置 Download PDF

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WO2023097781A1
WO2023097781A1 PCT/CN2021/138042 CN2021138042W WO2023097781A1 WO 2023097781 A1 WO2023097781 A1 WO 2023097781A1 CN 2021138042 W CN2021138042 W CN 2021138042W WO 2023097781 A1 WO2023097781 A1 WO 2023097781A1
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vessel wall
transducer
frequency
blood vessel
longitudinal displacement
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PCT/CN2021/138042
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English (en)
French (fr)
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马腾
吴铮杰
张琪
高磊
谭清源
高泽平
郑海荣
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中国科学院深圳先进技术研究院
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Publication of WO2023097781A1 publication Critical patent/WO2023097781A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
    • A61B8/0891—Detecting organic movements or changes, e.g. tumours, cysts, swellings for diagnosis of blood vessels
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/12—Diagnosis using ultrasonic, sonic or infrasonic waves in body cavities or body tracts, e.g. by using catheters

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  • the present application relates to the technical field of medical ultrasound, in particular to a dual-frequency intravascular ultrasound transducer, a method and a device for calculating Young's modulus of a blood vessel wall.
  • dual-frequency transducers used to detect the superficial tissues of the human body, such as the chest, abdomen, and neck.
  • these dual-frequency transducers detect the superficial tissues of the human body, they usually need Ultrasonic radiation force causes tissue displacement, and then the echo signal when the tissue is displaced is collected through a high-frequency transducer, and elastic imaging is performed based on the echo signal to determine whether there is a lesion in the superficial tissue.
  • the current dual-frequency transducer cannot be used to detect vascular plaque, and the energy of the ultrasonic radiation force generated by the low-frequency transducer is relatively small, causing insignificant tissue displacement, resulting in low accuracy of detection results.
  • the present application provides a dual-frequency intravascular ultrasonic transducer, a method and device for calculating the Young's modulus of the blood vessel wall, which are used to solve the problem that the energy of the ultrasonic radiation force produced by the low-frequency transducer in the prior art is small and The problem that the dual-frequency transducer in the prior art cannot be used to detect vascular plaques, the technical solution is as follows:
  • a dual-frequency intravascular ultrasound transducer comprising: a low-frequency focusing transducer;
  • the outer surface of the matching layer of the low-frequency focusing transducer is recessed inward, forming a spherical concave surface.
  • the spherical concave surface is used to make the low-frequency focusing transducer generate focused ultrasonic radiation force.
  • the shear wave of the longitudinal displacement of the vessel wall so as to detect the plaque condition of the vessel based on the longitudinal displacement of the vessel wall.
  • inventions also include: high frequency transducer and catheter;
  • the other end of the catheter is used to extend into the blood vessel, so that the focused ultrasonic radiation force generated by the low-frequency focusing transducer and the ultrasonic wave generated by the high-frequency transducer are transmitted into the blood vessel, and the echo generated by the ultrasonic wave in the blood vessel is transmitted back to the blood vessel.
  • High frequency transducer is used to extend into the blood vessel, so that the focused ultrasonic radiation force generated by the low-frequency focusing transducer and the ultrasonic wave generated by the high-frequency transducer are transmitted into the blood vessel, and the echo generated by the ultrasonic wave in the blood vessel is transmitted back to the blood vessel.
  • High frequency transducer High frequency transducer.
  • a method for calculating Young's modulus of a blood vessel wall, based on the above-mentioned dual-frequency ultrasonic transducer, comprising:
  • the high-frequency transducer is used to collect the first echo signal when there is no longitudinal displacement of the blood vessel wall;
  • the Young's modulus of the vessel wall is determined.
  • the second echo signal of the vessel wall when the longitudinal displacement occurs is collected, including:
  • Focused ultrasonic radiation force is generated based on the low-frequency focusing transducer, so that the focused ultrasonic radiation force acts on the vessel wall to generate shear waves, and the transverse propagation of the shear waves causes longitudinal displacement of the vessel wall;
  • the second echo signal when the longitudinal displacement of the blood vessel wall occurs is collected based on the high-frequency transducer.
  • determining the Young's modulus of the vessel wall includes:
  • the Young's modulus of the vessel wall is calculated.
  • the propagation velocity of the shear wave is determined, including:
  • the propagation velocity of the shear wave is calculated.
  • a device for calculating Young's modulus of a blood vessel wall comprising: a first echo signal acquisition module, a second echo signal acquisition module, and a Young's modulus determination module;
  • the first echo signal acquisition module is used to acquire the first echo signal when the vessel wall has no longitudinal displacement based on the high-frequency transducer after the catheter is inserted into the blood vessel;
  • the second echo signal acquisition module is used to acquire the second echo signal when the longitudinal displacement of the vessel wall occurs based on the low-frequency focusing transducer and the high-frequency transducer;
  • the Young's modulus determination module is configured to determine the Young's modulus of the blood vessel wall based on the first echo signal and the second echo signal.
  • the second echo signal acquisition module includes: an ultrasonic radiation force generation sub-module and a second echo signal acquisition sub-module;
  • the ultrasonic radiation force generation sub-module is used to generate focused ultrasonic radiation force based on a low-frequency focused transducer, so that the focused ultrasonic radiation force acts on the vessel wall to generate shear waves, and the transverse propagation of the shear waves causes longitudinal displacement of the vessel wall;
  • the second echo signal acquisition sub-module is configured to collect the second echo signal based on the high-frequency transducer when the longitudinal displacement of the vessel wall occurs when the transverse propagation of the shear wave causes the longitudinal displacement of the vessel wall.
  • the Young's modulus determination module includes: a longitudinal displacement calculation module, a propagation velocity determination module and a Young's modulus calculation module;
  • a longitudinal displacement calculation module configured to calculate the longitudinal displacement of the vessel wall according to the first echo signal and the second echo signal
  • the propagation velocity determination module is used to determine the propagation velocity of the shear wave according to the longitudinal displacement of the vessel wall and the transducer distance, wherein the transducer distance is the center distance between the low-frequency focusing transducer and the high-frequency transducer;
  • the Young's modulus calculation module is used for calculating the Young's modulus of the blood vessel wall according to the propagation velocity of the shear wave and the tissue density of the blood vessel wall.
  • the propagation velocity determination module includes: a longitudinal displacement peak determination module and a propagation velocity calculation module;
  • a peak longitudinal displacement determination module configured to determine the peak longitudinal displacement of the vessel wall according to the longitudinal displacement of the vessel wall
  • the propagation velocity calculation module is used for calculating the propagation velocity of the shear wave according to the peak longitudinal displacement of the vessel wall and the transducer distance.
  • the dual-frequency intravascular ultrasound transducer includes a low-frequency focusing transducer, and the outer surface of the matching layer of the low-frequency focusing transducer is concaved inward to form a spherical concave surface, which is used for Make the low-frequency focusing transducer generate focused ultrasonic radiation force, which is used to generate a shear wave in the blood vessel that can propagate transversely and cause longitudinal displacement of the vessel wall, so as to detect plaque in the vessel based on the longitudinal displacement of the vessel wall Condition.
  • the spherical concave surface enables the low-frequency focusing transducer to generate focused ultrasonic radiation force.
  • the energy of the focused ultrasonic radiation force is larger. Therefore, when the shear wave is generated by acting on the vessel wall, the transverse propagation of the shear wave can cause a large longitudinal displacement of the vessel wall, and the plaque condition of the vessel can be accurately detected based on the large longitudinal displacement of the vessel wall.
  • Fig. 1 is the structural representation of the low-frequency transducer that dual-frequency transducer comprises in the prior art
  • FIG. 2 is a schematic structural diagram of a low-frequency focusing transducer provided by an embodiment of the present application
  • FIG. 3 is a schematic structural view of the low-frequency focusing transducer, copper ring and steel ball provided by the embodiment of the present application;
  • FIG. 4 is a schematic structural diagram of a dual-frequency intravascular ultrasound transducer provided in an embodiment of the present application
  • Fig. 5 is a schematic diagram of the relationship between the control system based on the dual-frequency intravascular ultrasound transducer
  • Fig. 6 is a schematic flowchart of a method for calculating Young's modulus of a blood vessel wall provided by the embodiment of the present application;
  • Fig. 7 is the working sequence chart of low-frequency focusing transducer, high-frequency transducer and motor;
  • Figure 8a is a graph showing the longitudinal displacement of the vessel wall of a normal isolated porcine coronary artery over time
  • Figure 8b is a time-dependent diagram of the longitudinal displacement of the blood vessel wall after the isolated porcine coronary artery is hardened
  • Figure 8c is a comparison diagram of the longitudinal displacement of the vessel wall of the normal isolated porcine coronary artery and the longitudinal displacement of the vessel wall of the isolated porcine coronary artery after hardening;
  • FIG. 9 is a schematic structural diagram of a device for calculating Young's modulus of a blood vessel wall provided in an embodiment of the present application.
  • FIG. 10 is a block diagram of a hardware structure of a device for calculating Young's modulus of a blood vessel wall provided by an embodiment of the present application.
  • Atherosclerosis is characterized by the accumulation of calcium, fibrin, cholesterol, fat, and other substances deposited in the intima of large and medium-sized arteries to form plaques, the rupture of which is the main factor leading to acute cardiovascular events.
  • the dual-frequency transducers in the prior art cannot be used to detect atherosclerotic plaques
  • the low-frequency transducers in the prior art see FIG. Schematic diagram of the structure of the low-frequency transducer contained in the device, the low-frequency transducer includes a matching layer, a wafer layer and a backing layer
  • the inventors of this case provided a A dual-frequency intravascular ultrasonic transducer includes a low-frequency focusing transducer, and the outer surface of the matching layer of the low-frequency focusing transducer is concaved inward to form a focusing spherical surface.
  • Fig. 2 is a schematic diagram of the structure of the low-frequency focusing transducer provided by the embodiment of the present application, it can be seen that the matching layer, the wafer layer and the backing layer of the low-frequency focusing transducer will be recessed inwards on the side close to the wafer layer .
  • the spherical concave surface is used to make the low-frequency focusing transducer generate focused ultrasonic radiation force, and the focused ultrasonic radiation force is used to generate shear waves in the blood vessel that can propagate transversely and cause longitudinal displacement of the blood vessel wall, so that based on the longitudinal displacement of the blood vessel wall Displacement detection of plaque in blood vessels.
  • the spherical concave surface enables the low-frequency focusing transducer to generate focused ultrasonic radiation force.
  • the embodiment of the present application provides The energy of the focused ultrasonic radiation force is large, so when it acts on the vessel wall to generate a shear wave, the transverse propagation of the shear wave can cause a large longitudinal displacement of the vessel wall, which can be accurately detected based on the large longitudinal displacement of the vessel wall.
  • the situation of plaque out of the blood vessel solves the problem that the dual-frequency transducer in the prior art cannot be used to detect the plaque of the blood vessel, and the energy of the ultrasonic radiation force generated by the low-frequency transducer is small, and the tissue displacement caused by it is not obvious, resulting in The problem of low accuracy of detection results.
  • the present application provides a method for manufacturing a low-frequency focusing transducer.
  • Fig. 3 it is a schematic diagram of the structure of the low frequency focusing transducer, copper ring and steel ball provided by the embodiment of the present application.
  • Step 2 Place the cut unfocused low-frequency transducer in the copper ring, and fill it with glue (epoxy resin in Figure 3) to fix it ;
  • Step 3 Press the unfocused low-frequency transducer into shape by using a steel ball in an environment heated at 90°C to form a low-frequency focused transducer;
  • Step 4 Take out the low-frequency focused transducer from the copper ring, and convert the low-frequency focused transducer Cut off the glue used to fix the device.
  • the above process of manufacturing the low-frequency focusing transducer is only an example, and is not intended to limit the method of manufacturing the low-frequency focusing transducer.
  • a dual-frequency intravascular ultrasound transducer provided in the embodiment of the present application may also include: a high-frequency transducer and a catheter, as shown in Figure 4 for details
  • the embodiment provides a schematic structural diagram of a dual-frequency intravascular ultrasound transducer, which includes a low-frequency focusing transducer 1 , a high-frequency transducer 2 and a catheter 3 .
  • Fig. 2 there is a pit on the outer surface of one end of the conduit 3, and the low-frequency focusing transducer 1 and the high-frequency transducer 2 are aligned and assembled in the pit along the direction in which the conduit 1 extends, and the low-frequency focusing transducer 1 and the high-frequency transducer
  • the transducers 2 are all connected to the conduit 3 through lead wires welded inside the conduit 3 .
  • the other end of the catheter 3 is used to extend into the blood vessel, so that the focused ultrasonic radiation force generated by the low-frequency focusing transducer 1 and the ultrasonic wave generated by the high-frequency transducer 2 are transmitted into the blood vessel, and the echo generated by the ultrasonic wave in the blood vessel The waves are transmitted back to the high frequency transducer 2.
  • one end of the conduit 3 is a smooth outer surface, and there is a pit on the smooth outer surface, so that the low-frequency focusing transducer 1 and the high-frequency transducer 2 can be aligned and assembled in the pit along the direction in which the conduit 1 extends,
  • the low-frequency focusing transducer 1 and the high-frequency transducer 2 can be respectively connected to the conduit 3 by welding lead wires inside the conduit 3 .
  • the other end of the catheter 3 has a threaded outer surface, and the other end can be inserted into the blood vessel, and can freely expand and contract in the blood vessel to detect deep blood vessel plaques.
  • the inside of the catheter 3 is a hollow structure, so that the focused ultrasonic radiation force generated by the low-frequency focusing transducer 1 and the ultrasonic waves generated by the high-frequency transducer 2 can be transmitted into the blood vessel, and the echo generated by the ultrasonic wave in the blood vessel can be transmitted back to the blood vessel.
  • High frequency transducer 2 The inside of the catheter 3 is a hollow structure, so that the focused ultrasonic radiation force generated by the low-frequency focusing transducer 1 and the ultrasonic waves generated by the high-frequency transducer 2 can be transmitted into the blood vessel, and the echo generated by the ultrasonic wave in the blood vessel can be transmitted back to the blood vessel.
  • High frequency transducer 2 is a hollow structure, so that the focused ultrasonic radiation force generated by the low-frequency focusing transducer 1 and the ultrasonic waves generated by the high-frequency transducer 2 can be transmitted into the blood vessel, and the echo generated by the ultrasonic wave in the blood vessel can be transmitted back to the blood vessel.
  • the dual-frequency intravascular ultrasound transducer provided in the present application can have two working modes, namely, a high-resolution B-mode imaging mode and a high-resolution ultrasound elastography mode.
  • the high-frequency transducer 2 works independently to provide a high-resolution B-mode image result of the vessel wall. Specifically, during the plaque detection process, the high-frequency transducer 2 is used to collect the echo signal of the blood vessel wall at the corresponding position. Since the high-frequency transducer 2 can only collect the echo signal of the blood vessel wall at one position at a time, the The motor rotates one turn, and the echo signal of the blood vessel wall can be collected for one turn. That is to say, the dual-frequency intravascular ultrasonic transducer provided in the embodiment of the present application can collect the blood vessel through the high-frequency transducer 1 driven by the motor. Combined with the echo signal around the wall and the stretching ability of the catheter 3, the echo signal at any position of the blood vessel wall can be collected.
  • the embodiment of the present application defines the above-mentioned echo signal as the first echo signal, which is generated without longitudinal displacement of the blood vessel wall, and carries structural information of the blood vessel wall , such as information on the degree of stenosis of the blood vessel wall, etc., are subsequently processed by performing envelope detection, logarithmic compression, etc. on the first echo signal (for example, processing by a filter, a data acquisition card, a signal processor, etc. shown in FIG. 5 ), A 2D image can be formed, and the 2D image can provide gray scale change information to calculate the structure information of the blood vessel wall, and provide real-time data for other subsequent analysis.
  • the low-frequency focusing transducer 1 is used as the excitation transducer
  • the high-frequency transducer 2 is used as the detection transducer
  • the low-frequency focusing transducer 1 and the high-frequency transducer 2 work simultaneously to achieve Used to detect the longitudinal displacement of the vessel wall.
  • the high voltage is used to excite the low-frequency focused transducer 1, which can produce a focused, high-energy Ultrasonic radiation force, the focused ultrasonic radiation force acts on the blood vessel wall to generate shear waves, which in turn cause longitudinal displacement of the blood vessel wall;
  • the signal generated by the signal generator is processed by the pulse receiver to generate a pulse signal for exciting the high-frequency transducer 2 , so that the high-frequency transducer 2 continuously generates ultrasonic waves, and collects high-resolution echo signals through oversampling.
  • the above-mentioned high-resolution echo signal is defined as the second echo signal in the embodiment of the present application, and the second echo signal is generated when the blood vessel wall undergoes longitudinal displacement, and the second echo signal carries the blood vessel wall
  • biomechanical information such as the Young's modulus of the blood vessel wall can be obtained by performing correlation calculation on the first echo signal and the second echo signal.
  • Fig. 6 shows a schematic flowchart of the method for calculating the Young's modulus of the blood vessel wall provided by the embodiment of the present application.
  • the Young's modulus calculation method for the blood vessel wall can calculate the Young's modulus of the blood vessel wall based on the above-mentioned dual-frequency ultrasonic transducer
  • the method for calculating the Young's modulus of the blood vessel wall may include:
  • Step S601 after the catheter is inserted into the blood vessel, the first echo signal is collected based on the high-frequency transducer when the blood vessel wall has no longitudinal displacement.
  • the dual-frequency intravascular ultrasound transducer is in the high-resolution B-mode imaging mode.
  • the high-frequency transducer 2 (detection transducer) works alone.
  • the high-frequency transducer The device 1 can collect the first echo signal when there is no longitudinal displacement of the vessel wall.
  • Step S602 based on the low-frequency focusing transducer and the high-frequency transducer, collecting a second echo signal when the vessel wall is longitudinally displaced.
  • the process of this step may specifically include: generating a focused ultrasonic radiation force based on a low-frequency focusing transducer, so that the focused ultrasonic radiation force acts on the vessel wall to generate a shear wave, and the transverse propagation of the shear wave causes the vessel wall to vibrate.
  • Longitudinal displacement when the longitudinal displacement of the vessel wall is caused by the transverse propagation of the shear wave, the second echo signal when the longitudinal displacement of the vessel wall occurs is collected based on a high-frequency transducer.
  • the dual-frequency intravascular ultrasound transducer is in the high-resolution ultrasound elastography mode, and the low-frequency focusing transducer 1 (excitation transducer) and the high-frequency transducer 2 (detection transducers) work at the same time, among which, the low-frequency focusing transducer 1 only needs to work for 200 ⁇ s, and within this 200 ⁇ s, the low-frequency focusing transducer 1 can generate focused ultrasonic radiation force, and the focused ultrasonic radiation force acts on the blood vessel wall Shear waves are generated, and the transverse propagation of the shear waves causes longitudinal displacement of the vessel wall.
  • the high-frequency transducer 2 needs to work all the time, so as to collect the second echo signal when the longitudinal displacement of the vessel wall occurs when the transverse propagation of the shear wave causes the longitudinal displacement of the vessel wall.
  • the motor can drive the dual-frequency intravascular ultrasonic transducer to rotate.
  • the first echo signal and the second echo signal at the position after the rotation are collected according to the above process.
  • the first echo signal and the second echo signal of the circle are collected according to the above process.
  • Step S603 based on the first echo signal and the second echo signal, determine the Young's modulus of the blood vessel wall.
  • the first echo signal and the second echo signal can be used to calculate the Young's modulus of the blood vessel wall.
  • the Young's modulus can reflect the degree of softness and hardness of the blood vessel wall. According to different Young's moduli, it can be It can intuitively distinguish normal blood vessel walls and plaques (disease blood vessel walls), and at the same time distinguish plaques of different natures, so as to accurately evaluate atherosclerotic diseases.
  • the process of calculating the Young's modulus of the vessel wall in this step may include:
  • the difference between the first echo signal and the second echo signal can be calculated by using a normalized cross-correlation algorithm to obtain the longitudinal displacement of the vessel wall caused by the shear wave.
  • the longitudinal displacement of the vessel wall can be calculated according to the following formula:
  • c(j) is the longitudinal displacement of the vessel wall
  • f r and f s are the first echo signal and the second echo signal respectively
  • M is the sampling window size.
  • the normal blood vessel wall was simulated with the isolated porcine coronary artery before soaking in formalin, and the blood vessel wall with hard plaque was simulated with the isolated pig coronary artery after soaking in formalin.
  • the test results can be seen in Figure 8, (a) is a diagram of the longitudinal displacement of the normal isolated porcine coronary artery with time, and (b) is a diagram of the longitudinal displacement of the isolated porcine coronary artery with time after the hardening , (c) is the comparison between the two. It can be seen that the application can detect the longitudinal displacement of the vessel wall caused by the shear wave, and can also distinguish the normal vessel wall and the diseased vessel wall with different hardness.
  • the process of this step may include the following steps:
  • the longitudinal displacement of the blood vessel wall is an amount that changes with time, and thus the peak value of the longitudinal displacement of the blood vessel wall can be determined.
  • v sw is the propagation velocity of the shear wave
  • d e is the center distance between the high-frequency transducer 2 and the low-frequency focusing transducer
  • t p is the peak longitudinal displacement of the vessel wall calculated by the normalized cross-correlation algorithm .
  • the Young's modulus E of the blood vessel wall can be calculated by using the tissue density ⁇ of the blood vessel wall.
  • the method for calculating the Young's modulus of the blood vessel wall uses a dual-frequency intravascular ultrasonic transducer to estimate the Young's modulus of the blood vessel wall from the measured longitudinal displacement and the peak value of the longitudinal displacement of the blood vessel wall.
  • the Young's modulus parameter is The clear physical meaning is closely related to the susceptibility of the plaque.
  • the invention expands the new application field of the ultrasonic elastography technology, and can provide a new clinical basis for the pathological research and diagnosis of atherosclerosis.
  • the embodiment of the present application also provides a device for calculating the Young's modulus of the blood vessel wall.
  • the device for calculating the Young's modulus of the blood vessel wall provided by the embodiment of the present application is described below.
  • the device for calculating the Young's modulus of the blood vessel wall described below is the same as that described above
  • the described calculation method of Young's modulus of blood vessel wall can be referred to each other correspondingly.
  • FIG. 9 shows a schematic structural diagram of a device for calculating Young's modulus of a blood vessel wall provided by an embodiment of the present application.
  • the device for calculating Young's modulus of a blood vessel wall may include: first echo signal acquisition Module 901 , second echo signal acquisition module 902 and Young's modulus determination module 903 .
  • the first echo signal acquisition module 901 is configured to acquire, based on the high-frequency transducer, the first echo signal when there is no longitudinal displacement of the vessel wall after the catheter is inserted into the blood vessel.
  • the second echo signal acquisition module 902 is configured to acquire the second echo signal when the vessel wall is longitudinally displaced based on the low-frequency focusing transducer and the high-frequency transducer.
  • the Young's modulus determination module 903 is configured to determine the Young's modulus of the blood vessel wall based on the first echo signal and the second echo signal.
  • the second echo signal acquisition module 902 may include: an ultrasonic radiation force generating submodule and a second echo signal acquisition submodule.
  • the ultrasonic radiation force generation sub-module is used to generate focused ultrasonic radiation force based on the low-frequency focusing transducer, so that the focused ultrasonic radiation force acts on the vessel wall to generate shear waves, and the transverse propagation of the shear waves causes the longitudinal direction of the vessel wall. displacement.
  • the second echo signal acquisition sub-module is configured to collect the second echo signal based on the high-frequency transducer when the longitudinal displacement of the vessel wall occurs when the transverse propagation of the shear wave causes the longitudinal displacement of the vessel wall.
  • the above-mentioned Young's modulus determination module may include: a longitudinal displacement calculation module, a propagation velocity determination module, and a Young's modulus calculation module.
  • the longitudinal displacement calculation module is configured to calculate the longitudinal displacement of the vessel wall according to the first echo signal and the second echo signal.
  • the propagation velocity determination module is used to determine the propagation velocity of the shear wave according to the longitudinal displacement of the vessel wall and the transducer distance, wherein the transducer distance is the center distance between the low-frequency focusing transducer and the high-frequency transducer.
  • the Young's modulus calculation module is used for calculating the Young's modulus of the blood vessel wall according to the propagation velocity of the shear wave and the tissue density of the blood vessel wall.
  • the above propagation velocity determination module may include: a longitudinal displacement peak determination module and a propagation velocity calculation module.
  • the peak longitudinal displacement determination module is configured to determine the peak longitudinal displacement of the vessel wall according to the longitudinal displacement of the vessel wall.
  • the propagation velocity calculation module is used for calculating the propagation velocity of the shear wave according to the peak longitudinal displacement of the vessel wall and the transducer distance.
  • FIG. 10 shows a block diagram of a hardware structure of a Young's modulus calculation device for a blood vessel wall.
  • the hardware structure of the Young's modulus calculation device for a blood vessel wall may include: at least one processor 1001, at least one communication interface 1002, at least one memory 1003 and at least one communication bus 1004;
  • the number of processor 1001, communication interface 1002, memory 1003, and communication bus 1004 is at least one, and the processor 1001, communication interface 1002, and memory 1003 complete mutual communication through the communication bus 1004;
  • Processor 1001 may be a central processing unit CPU, or a specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention, etc.;
  • CPU central processing unit
  • ASIC Application Specific Integrated Circuit
  • the memory 1003 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory;
  • the memory 1003 stores a program
  • the processor 1001 can call the program stored in the memory 1003, and the program is used for:
  • the high-frequency transducer is used to collect the first echo signal when there is no longitudinal displacement of the blood vessel wall;
  • the Young's modulus of the vessel wall is determined.
  • the embodiment of the present application also provides a readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the above-mentioned method for calculating the Young's modulus of the blood vessel wall is realized.

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Abstract

一种双频血管内超声换能器、血管壁杨氏模量计算方法和装置。双频血管内超声换能器包括低频聚焦换能器（1），低频聚焦换能器（1）的匹配层所在外表面向内凹陷，形成球状凹面，球状凹面用于使低频聚焦换能器（1）产生聚焦的超声辐射力，聚焦的超声辐射力用于在血管内产生能够横向传播引起血管壁的纵向位移的剪切波，以便基于血管壁的纵向位移检测血管的斑块情况。球状凹面使得低频聚焦换能器（1）能产生聚焦的超声辐射力，聚焦的超声辐射力的能量较大，从而作用于血管壁产生剪切波时，剪切波的横向传播能够引起血管壁较大的纵向位移，基于血管壁的较大纵向位移即可准确检测出血管的斑块情况。

Description

双频血管内超声换能器、血管壁杨氏模量计算方法和装置 技术领域
本申请涉及医学超声技术领域，特别是涉及一种双频血管内超声换能器、血管壁杨氏模量计算方法和装置。
背景技术
目前，存在一些用于检测人体表浅组织如胸部、腹部、颈部的情况的双频换能器，这些双频换能器在检测人体表浅组织时，通常需要基于低频换能器产生的超声辐射力引起组织位移，然后再通过高频换能器采集在组织发生位移时的回波信号，基于回波信号进行弹性成像，以此确定表浅组织是否存在病变。
但是，目前的双频换能器无法用于检测血管斑块情况，并且低频换能器产生的超声辐射力的能量较小，引起的组织位移不明显，导致检测结果的准确性较低。
发明内容
有鉴于此，本申请提供了一种双频血管内超声换能器、血管壁杨氏模量计算方法和装置，用于解决现有技术低频换能器产生的超声辐射力的能量较小并且现有技术双频换能器无法用于检测血管斑块情况的问题，其技术方案如下：
一种双频血管内超声换能器，包括：低频聚焦换能器；
低频聚焦换能器的匹配层所在外表面向内凹陷，形成球状凹面，球状凹面用于使低频聚焦换能器产生聚焦的超声辐射力，聚焦的超声辐射力用于在血管内产生能够横向传播引起血管壁的纵向位移的剪切波，以便基于血管壁的纵向位移检测血管的斑块情况。
可选的，还包括：高频换能器和导管；
导管一端的外表面上具有凹坑，低频聚焦换能器和高频换能器沿导管延伸的方向对齐装配在凹坑内，且低频聚焦换能器和高频换能器均通过焊接在导管内部的引线与导管连接；
导管另一端用于伸入血管内，使得低频聚焦换能器产生的聚焦的超声辐射力和高频换能器产生的超声波传输至血管内，以及，使得超声波在血管内产生的回波传输回高频换能器。
一种血管壁杨氏模量计算方法，基于如上述的双频超声换能器，包括：
在导管伸入血管后，基于高频换能器采集在血管壁未发生纵向位移时的第一回波信号；
基于低频聚焦换能器和高频换能器采集血管壁在发生纵向位移时的第二回波信号；
基于第一回波信号和第二回波信号，确定血管壁的杨氏模量。
可选的，基于低频聚焦换能器和高频换能器采集血管壁在发生纵向位移时的第二回波信号，包括：
基于低频聚焦换能器产生聚焦的超声辐射力，以便聚焦的超声辐射力作用于血管壁产生剪切波，剪切波的横向传播引起血管壁的纵向位移；
在剪切波的横向传播引起血管壁的纵向位移时，基于高频换能器采集血管壁在发生纵向位移时的第二回波信号。
可选的，基于第一回波信号和第二回波信号，确定血管壁的杨氏模量，包括：
根据第一回波信号和第二回波信号，计算血管壁的纵向位移；
根据血管壁的纵向位移和换能器距离，确定剪切波的传播速度，其中，换能器距离为低频聚焦换能器和高频换能器的中心距离；
根据剪切波的传播速度和血管壁组织密度，计算血管壁的杨氏模量。
可选的，根据血管壁的纵向位移，确定剪切波的传播速度，包括：
根据血管壁的纵向位移，确定血管壁的纵向位移峰值；
根据血管壁的纵向位移峰值和换能器距离，计算剪切波的传播速度。
一种血管壁杨氏模量计算装置，基于如上述的双频超声换能器，包括：第一回波信号采集模块、第二回波信号采集模块和杨氏模量确定模块；
第一回波信号采集模块，用于在导管伸入血管后，基于高频换能器采集在血管壁未发生纵向位移时的第一回波信号；
第二回波信号采集模块，用于基于低频聚焦换能器和高频换能器采集血管壁在发生纵向位移时的第二回波信号；
杨氏模量确定模块，用于基于第一回波信号和第二回波信号，确定血管壁的杨氏模量。
可选的，第二回波信号采集模块，包括：超声辐射力产生子模块和第二回波信号采集子模块；
超声辐射力产生子模块，用于基于低频聚焦换能器产生聚焦的超声辐射力，以便聚焦的超声辐射力作用于血管壁产生剪切波，剪切波的横向传播引起血管壁的纵向位移；
第二回波信号采集子模块，用于在剪切波的横向传播引起血管壁的纵向位移时，基于高频换能器采集血管壁在发生纵向位移时的第二回波信号。
可选的，杨氏模量确定模块，包括：纵向位移计算模块、传播速度确定模块和杨氏模量计算模块；
纵向位移计算模块，用于根据第一回波信号和第二回波信号，计算血管壁的纵向位移；
传播速度确定模块，用于根据血管壁的纵向位移和换能器距离，确定剪切波的传播速度，其中，换能器距离为低频聚焦换能器和高频换能器的中心距离；
杨氏模量计算模块，用于根据剪切波的传播速度和血管壁组织密度，计算血管壁的杨氏模量。
可选的，传播速度确定模块，包括：纵向位移峰值确定模块和传播速度计算模块；
纵向位移峰值确定模块，用于根据血管壁的纵向位移，确定血管壁的纵向位移峰值；
传播速度计算模块，用于根据血管壁的纵向位移峰值和换能器距离，计算剪切波的传播速度。
经由上述的技术方案可知，本申请提供的双频血管内超声换能器，包括低频聚焦换能器，该低频聚焦换能器的匹配层所在外表面向内凹陷，形成球 状凹面，球状凹面用于使低频聚焦换能器产生聚焦的超声辐射力，聚焦的超声辐射力用于在血管内产生能够横向传播引起血管壁的纵向位移的剪切波，以便基于血管壁的纵向位移检测血管的斑块情况。本申请中，球状凹面使得低频聚焦换能器能够产生聚焦的超声辐射力，相对比现有技术中的低频换能器产生的超声辐射力的能量，该聚焦的超声辐射力的能量较大，从而作用于血管壁产生剪切波时，剪切波的横向传播能够引起血管壁较大的纵向位移，基于血管壁的较大纵向位移即可准确检测出血管的斑块情况。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。
图1为现有技术中双频换能器包含的低频换能器的结构示意图；
图2为本申请实施例提供的低频聚焦换能器的结构示意图；
图3为本申请实施例提供的低频聚焦换能器、铜环和钢球的结构示意图；
图4为本申请实施例提供的一种双频血管内超声换能器的结构示意图；
图5为基于双频血管内超声换能器的控制系统的关系情况示意图；
图6本申请实施例提供的一种血管壁杨氏模量计算方法的流程示意图；
图7为低频聚焦换能器、高频换能器和电机的工作时序图；
图8a为正常离体猪冠脉的血管壁纵向位移随时间变化图；
图8b为离体猪冠脉变硬后的血管壁纵向位移随时间变化图；
图8c为正常离体猪冠脉的血管壁纵向位移与离体猪冠脉变硬后的血管壁纵向位移的对比图；
图9为本申请实施例提供的一种血管壁杨氏模量计算装置的结构示意图；
图10为本申请实施例提供的一种血管壁杨氏模量计算设备的硬件结构框图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
动脉血管粥样硬化的特征是钙、纤维蛋白、胆固醇、脂肪和其他物质沉积在大中型动脉的内膜积聚形成斑块，该硬化斑块破裂是导致急性心血管时间的主要因素。
鉴于现有技术中的双频换能器无法用于检测血管粥样硬化斑块情况，并且，现有技术中的低频换能器(参见图1所示，为现有技术中双频换能器包含的低频换能器的结构示意图，该低频换能器包括匹配层、晶片层和背衬层)产生的超声辐射力的能量较小的问题，本案发明人经深入研究后，提供了一种双频血管内超声换能器，该双频血管内超声换能器包括低频聚焦换能器，该低频聚焦换能器的匹配层所在外表面向内凹陷，形成聚焦球面。参见图2所示，为本申请实施例提供的低频聚焦换能器的结构示意图，可见，低频聚焦换能器的匹配层、晶片层和背衬层靠近晶片层的一侧均会向内凹陷。
其中，球状凹面用于使低频聚焦换能器产生聚焦的超声辐射力，聚焦的超声辐射力用于在血管内产生能够横向传播引起血管壁的纵向位移的剪切波，以便基于血管壁的纵向位移检测血管的斑块情况。
具体来说，本申请实施例中，球状凹面使得低频聚焦换能器能够产生聚焦的超声辐射力，相对比现有技术中的低频换能器产生的超声辐射力的能量，本申请实施例提供的聚焦的超声辐射力的能量较大，从而作用于血管壁产生剪切波时，剪切波的横向传播能够引起血管壁较大的纵向位移，基于血管壁的较大纵向位移即可准确检测出血管的斑块情况，解决了现有技术双频换能器无法用于检测血管斑块情况，并且，低频换能器产生的超声辐射力的能量较小，引起的组织位移不明显，导致检测结果的准确性较低的问题。
可选的，本申请提供了一种低频聚焦换能器的制作方法。参见图3所示，为本申请实施例提供的低频聚焦换能器、铜环和钢球的结构示意图，制作过程大体包括如下：步骤1：取内径与未聚焦低频换能器大小相当的铜环，加热至90℃用石蜡浸润，保证其内部光滑；步骤2：将切好的未聚焦低频换能器放置于铜环中，并填胶(图3中的环氧树脂)将其固定住；步骤3：利用钢球在 加热90℃的环境中将未聚焦低频换能器压制成型，形成低频聚焦换能器；步骤4：从铜环中取出低频聚焦换能器，将低频聚焦换能器固定用的胶切割掉。
需要说明的是，上述制作低频聚焦换能器的过程仅为示例，不作为对低频聚焦换能器的制作方法的限定。
在上述低频聚焦换能器的基础上，本申请实施例提供的一种双频血管内超声换能器还可以包括：高频换能器和导管，具体可以参见图4所示，为本申请实施例提供的一种双频血管内超声换能器的结构示意图，其中包括低频聚焦换能器1、高频换能器2和导管3。
图2中，导管3一端的外表面上具有凹坑，低频聚焦换能器1和高频换能器2沿导管1延伸的方向对齐装配在凹坑内，且低频聚焦换能器1和高频换能器2均通过焊接在导管3内部的引线与导管3连接。导管3另一端用于伸入血管内，使得低频聚焦换能器1产生的聚焦的超声辐射力和高频换能器2产生的超声波传输至血管内，以及，使得超声波在血管内产生的回波传输回高频换能器2。
具体来说，导管3的一端为光滑外表面，在该光滑外表面上具有凹坑，使得低频聚焦换能器1和高频换能器2可以沿导管1延伸的方向对齐装配在凹坑内，通过在导管3内部焊接引线，可使得低频聚焦换能器1和高频换能器2分别与导管3连接。导管3的另一端为具有螺纹的外表面，该另一端可伸入血管内，并在血管内自由伸缩以对深度较深的血管斑块进行检测。
导管3内部为中空结构，从而低频聚焦换能器1产生的聚焦的超声辐射力和高频换能器2产生的超声波可以传输至血管内，并且，超声波在血管内产生的回波可以传输回高频换能器2。
继上文介绍，本申请提供的双频血管内超声换能器可具有两种工作模式，即高分辨率B模式成像模式和高分辨率超声弹性成像模式。
其中，高分辨率B模式成像模式下，高频换能器2单独工作，以用于提供血管壁的高分辨率B模式图像结果。具体来说，在斑块检测过程中，通过高频换能器2采集对应位置的血管壁回波信号，由于高频换能器2每次仅能采集一个位置的血管壁回波信号，经电机带动旋转一圈，可以采集血管壁一圈的回波信号，也就是说，本申请实施例提供的双频血管内超声换能器能够在电机带动下，通过高频换能器1采集血管壁一圈的回波信号，同时结合导管3的伸缩能力，即可采集血管壁任何位置处的回波信号。
为便于后续介绍，本申请实施例将上述回波信号定义为第一回波信号，该第一回波信号是在血管壁未发生纵向位移的情况下产生的，其中携带有血管壁的结构信息，例如血管壁狭窄程度信息等，后续通过对第一回波信号进行包络检测、对数压缩等处理(例如通过图5所示的滤波器、数据采集卡、信号处理器等进行处理)，可形成2D图像，该2D图像能够提供灰度变化信息用以计算血管壁结构信息，给后续的其他分析提供实时数据。
高分辨率超声弹性成像模式下，低频聚焦换能器1作为激励换能器，高频换能器2作为检测换能器，低频聚焦换能器1和高频换能器2同时工作，以用于检测血管壁的纵向位移。具体来说，参见图5所示的基于双频血管内超声换能器的控制系统的连接关系示意图，首先通过信号发生器输出一个100μs到500μs的正弦信号，通过功率放大器将信号放大至一个较高的电压，用于激励低频聚焦换能器1，相比于高频换能器2和现有技术中的未聚焦换能器，低频聚焦换能器1能产生一个能量较大的聚焦的超声辐射力，聚焦的超声辐射力作用于血管壁产生剪切波，进而引起血管壁产生纵向位移；信号发生器产生的信号经脉冲接收器处理生成用于激励高频换能器2的脉冲信号，从而高频换能器2连续产生超声波，过采样采集高分辨率回波信号。
为便于后续介绍，本申请实施例将上述高分辨率回波信号定义为第二回波信号，该第二回波信号是在血管壁发生纵向位移的情况下产生的，其中携带有血管壁的纵向位移信息，后续通过对第一回波信号和第二回波信号进行相关计算，可得到血管壁的杨氏模量等生物力学信息。
为了使本领域技术人员更加理解本申请是如何计算出血管壁的杨氏模量的，以下通过本申请实施例提供的血管壁杨氏模量计算方法进行详细说明。
请参阅图6，示出了本申请实施例提供的血管壁杨氏模量计算方法的流程示意图，该血管壁杨氏模量计算方法可基于上述双频超声换能器计算血管壁杨氏模量，可选的，该血管壁杨氏模量计算方法可以包括：
步骤S601、在导管伸入血管后，基于高频换能器采集在血管壁未发生纵向位移时的第一回波信号。
参见图7所示的低频聚焦换能器、高频换能器和电机的工作时序图。在前100μs内，双频血管内超声换能器处于高分辨率B模式成像模式，此时高频换 能器2(检测换能器)单独工作，在导管3深入血管后，高频换能器1即可采集在血管壁未发生纵向位移时的第一回波信号。
步骤S602、基于低频聚焦换能器和高频换能器采集血管壁在发生纵向位移时的第二回波信号。
可选的，本步骤的过程具体可以包括：基于低频聚焦换能器产生聚焦的超声辐射力，以便聚焦的超声辐射力作用于血管壁产生剪切波，剪切波的横向传播引起血管壁的纵向位移；在剪切波的横向传播引起血管壁的纵向位移时，基于高频换能器采集血管壁在发生纵向位移时的第二回波信号。
具体来说，仍参见图7，在100μs～20ms内，双频血管内超声换能器处于高分辨率超声弹性成像模式，低频聚焦换能器1(激励换能器)和高频换能器2(检测换能器)同时工作，其中，低频聚焦换能器1仅需工作200μs，在该200μs内低频聚焦换能器1可产生聚焦的超声辐射力，聚焦的超声辐射力作用于血管壁产生剪切波，剪切波的横向传播引起血管壁的纵向位移。高频换能器2需要一直工作，以在剪切波的横向传播引起血管壁的纵向位移时，采集血管壁在发生纵向位移时的第二回波信号。
此后，电机可带动双频血管内超声换能器转动，在200ms后，按照上述过程采集转动后的位置处的第一回波信号和第二回波信号，如此重复，就可以采集血管壁一圈的第一回波信号和第二回波信号。
步骤S603、基于第一回波信号和第二回波信号，确定血管壁的杨氏模量。
在本步骤中，第一回波信号和第二回波信号可用于计算血管壁的杨氏模量，该杨氏模量可以反映血管壁的软硬程度，根据不同的杨氏模量大小可以直观的区分出正常血管壁和斑块(病变血管壁)，同时区分不同性质的斑块，从而能够对动脉粥样硬化疾病进行准确地评估。
可选的，本步骤计算血管壁的杨氏模量的过程可以包括：
S1、根据第一回波信号和第二回波信号，计算血管壁的纵向位移。
具体的，本步骤可通过归一化互相关算法，计算第一回波信号和第二回波信号之间的差异，得到剪切波引起的血管壁纵向位移。
可选的，可按照如下公式计算血管壁的纵向位移：
Figure PCTCN2021138042-appb-000001
式中，c(j)为血管壁的纵向位移，f r、f s分别为第一回波信号和第二回波信号，
Figure PCTCN2021138042-appb-000002
分别为第一回波信号和第二回波信号的平均值，M为取样的窗口大小。
为了验证本申请的可行性和有效性，用浸泡福尔马林前的离体猪冠脉模拟正常血管壁，用浸泡福尔马林后的离体猪冠脉模拟存在硬斑块血管壁，检测结果可参见图8所示，(a)为正常离体猪冠脉的血管壁纵向位移随时间变化图，(b)为离体猪冠脉变硬后的血管壁纵向位移随时间变化图，(c)为两者之间的对比，可见，本申请能检测出剪切波引起的血管壁纵向位移，同时也能区分出软硬度不同的正常血管壁与病变血管壁。
S2、根据血管壁的纵向位移和换能器距离，确定剪切波的传播速度，其中，换能器距离为低频聚焦换能器和高频换能器的中心距离。
可选的，本步骤的过程可以包括以下步骤：
S21、根据血管壁的纵向位移，确定血管壁的纵向位移峰值。
由上述S1可见，血管壁的纵向位移为随时间变化的量，由此即可确定出血管壁的纵向位移峰值。
S22、根据血管壁的纵向位移峰值和换能器距离，计算剪切波的传播速度。
可选的，可通过公式v sw＝d e/t p，计算剪切波的传播速度。
式中，v sw为剪切波的传播速度，d e为高频换能器2和低频聚焦换能器的中心距离，t p为通过归一化互相关算法计算得到的血管壁纵向位移峰值。
S3、根据剪切波的传播速度和血管壁组织密度，计算血管壁的杨氏模量。
具体的，计算出剪切波传播速度v sw后，再利用血管壁组织密度ρ，就可以计算出血管壁杨氏模量E。
可选的，可通过公式
Figure PCTCN2021138042-appb-000003
计算血管壁的杨氏模量。
本申请提供的血管壁杨氏模量计算方法，利用双频血管内超声换能器，从测量的血管壁纵向位移与纵向位移峰值估计出血管壁杨氏模量，该杨氏模量参数有明确的物理意义，与斑块易破损程度密切相关，本发明扩展了超声 弹性成像技术新的应用领域，能够为动脉粥样硬化的病理研究、诊断提供临床新依据。
本申请实施例还提供了一种血管壁杨氏模量计算装置，下面对本申请实施例提供的血管壁杨氏模量计算装置进行描述，下文描述的血管壁杨氏模量计算装置与上文描述的血管壁杨氏模量计算方法可相互对应参照。
请参阅图9，示出了本申请实施例提供的血管壁杨氏模量计算装置的结构示意图，如图9所示，该血管壁杨氏模量计算装置可以包括：第一回波信号采集模块901、第二回波信号采集模块902和杨氏模量确定模块903。
第一回波信号采集模块901，用于在导管伸入血管后，基于高频换能器采集在血管壁未发生纵向位移时的第一回波信号。
第二回波信号采集模块902，用于基于低频聚焦换能器和高频换能器采集血管壁在发生纵向位移时的第二回波信号。
杨氏模量确定模块903，用于基于第一回波信号和第二回波信号，确定血管壁的杨氏模量。
在一种可能的实现方式中，上述第二回波信号采集模块902可以包括：超声辐射力产生子模块和第二回波信号采集子模块。
其中，超声辐射力产生子模块，用于基于低频聚焦换能器产生聚焦的超声辐射力，以便聚焦的超声辐射力作用于血管壁产生剪切波，剪切波的横向传播引起血管壁的纵向位移。
第二回波信号采集子模块，用于在剪切波的横向传播引起血管壁的纵向位移时，基于高频换能器采集血管壁在发生纵向位移时的第二回波信号。
在一种可能的实现方式中，上述杨氏模量确定模块可以包括：纵向位移计算模块、传播速度确定模块和杨氏模量计算模块。
其中，纵向位移计算模块，用于根据第一回波信号和第二回波信号，计算血管壁的纵向位移。
传播速度确定模块，用于根据血管壁的纵向位移和换能器距离，确定剪切波的传播速度，其中，换能器距离为低频聚焦换能器和高频换能器的中心距离。
杨氏模量计算模块，用于根据剪切波的传播速度和血管壁组织密度，计算血管壁的杨氏模量。
在一种可能的实现方式中，上述传播速度确定模块可以包括：纵向位移峰值确定模块和传播速度计算模块。
其中，纵向位移峰值确定模块，用于根据血管壁的纵向位移，确定血管壁的纵向位移峰值。
传播速度计算模块，用于根据血管壁的纵向位移峰值和换能器距离，计算剪切波的传播速度。
本申请实施例还提供了一种血管壁杨氏模量计算设备。可选的，图10示出了血管壁杨氏模量计算设备的硬件结构框图，参照图10，该血管壁杨氏模量计算设备的硬件结构可以包括：至少一个处理器1001，至少一个通信接口1002，至少一个存储器1003和至少一个通信总线1004；
在本申请实施例中，处理器1001、通信接口1002、存储器1003、通信总线1004的数量为至少一个，且处理器1001、通信接口1002、存储器1003通过通信总线1004完成相互间的通信；
处理器1001可能是一个中央处理器CPU，或者是特定集成电路ASIC(Application Specific Integrated Circuit)，或者是被配置成实施本发明实施例的一个或多个集成电路等；
存储器1003可能包含高速RAM存储器，也可能还包括非易失性存储器(non-volatile memory)等，例如至少一个磁盘存储器；
其中，存储器1003存储有程序，处理器1001可调用存储器1003存储的程序，所述程序用于：
在导管伸入血管后，基于高频换能器采集在血管壁未发生纵向位移时的第一回波信号；
基于低频聚焦换能器和高频换能器采集血管壁在发生纵向位移时的第二回波信号；
基于第一回波信号和第二回波信号，确定血管壁的杨氏模量。
可选的，所述程序的细化功能和扩展功能可参照上文描述。
本申请实施例还提供一种可读存储介质，其上存储有计算机程序，所述计算机程序被处理器执行时，实现如上述血管壁杨氏模量计算方法。
可选的，所述程序的细化功能和扩展功能可参照上文描述。
最后，还需要说明的是，在本文中，诸如和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本申请。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本申请的精神或范围的情况下，在其它实施例中实现。因此，本申请将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (10)

  1. 一种双频血管内超声换能器，其特征在于，包括：低频聚焦换能器；
    所述低频聚焦换能器的匹配层所在外表面向内凹陷，形成球状凹面，所述球状凹面用于使所述低频聚焦换能器产生聚焦的超声辐射力，所述聚焦的超声辐射力用于在血管内产生能够横向传播引起血管壁的纵向位移的剪切波，以便基于所述血管壁的纵向位移检测所述血管的斑块情况。
  2. 根据权利要求1所述的双频血管内超声换能器，其特征在于，还包括：高频换能器和导管；
    所述导管一端的外表面上具有凹坑，所述低频聚焦换能器和所述高频换能器沿所述导管延伸的方向对齐装配在所述凹坑内，且所述低频聚焦换能器和所述高频换能器均通过焊接在所述导管内部的引线与所述导管连接；
    所述导管另一端用于伸入所述血管内，使得所述低频聚焦换能器产生的所述聚焦的超声辐射力和所述高频换能器产生的超声波传输至所述血管内，以及，使得所述超声波在所述血管内产生的回波传输回所述高频换能器。
  3. 一种血管壁杨氏模量计算方法，其特征在于，基于如权利要求2所述的双频超声换能器，包括：
    在所述导管伸入所述血管后，基于所述高频换能器采集在所述血管壁未发生所述纵向位移时的第一回波信号；
    基于所述低频聚焦换能器和所述高频换能器采集所述血管壁在发生所述纵向位移时的第二回波信号；
    基于所述第一回波信号和所述第二回波信号，确定所述血管壁的杨氏模量。
  4. 根据权利要求3所述的血管壁杨氏模量计算方法，其特征在于，所述基于所述低频聚焦换能器和所述高频换能器采集所述血管壁在发生所述纵向位移时的第二回波信号，包括：
    基于所述低频聚焦换能器产生所述聚焦的超声辐射力，以便所述聚焦的超声辐射力作用于所述血管壁产生剪切波，所述剪切波的横向传播引起所述血管壁的纵向位移；
    在所述剪切波的横向传播引起所述血管壁的纵向位移时，基于所述高频换能器采集所述血管壁在发生所述纵向位移时的所述第二回波信号。
  5. 根据权利要求4所述的血管壁斑块评估方法，其特征在于，所述基于所述第一回波信号和所述第二回波信号，确定所述血管壁的杨氏模量，包括：
    根据所述第一回波信号和所述第二回波信号，计算所述血管壁的纵向位移；
    根据所述血管壁的纵向位移和换能器距离，确定所述剪切波的传播速度，其中，所述换能器距离为所述低频聚焦换能器和所述高频换能器的中心距离；
    根据所述剪切波的传播速度和血管壁组织密度，计算所述血管壁的杨氏模量。
  6. 根据权利要求5所述的血管壁斑块评估方法，其特征在于，所述根据所述血管壁的纵向位移，确定所述剪切波的传播速度，包括：
    根据所述血管壁的纵向位移，确定所述血管壁的纵向位移峰值；
    根据所述血管壁的纵向位移峰值和所述换能器距离，计算所述剪切波的传播速度。
  7. 一种血管壁杨氏模量计算装置，其特征在于，基于如权利要求2所述的双频超声换能器，包括：第一回波信号采集模块、第二回波信号采集模块和杨氏模量确定模块；
    所述第一回波信号采集模块，用于在所述导管伸入所述血管后，基于所述高频换能器采集在所述血管壁未发生所述纵向位移时的第一回波信号；
    所述第二回波信号采集模块，用于基于所述低频聚焦换能器和所述高频换能器采集所述血管壁在发生所述纵向位移时的第二回波信号；
    所述杨氏模量确定模块，用于基于所述第一回波信号和所述第二回波信号，确定所述血管壁的杨氏模量。
  8. 根据权利要求7所述的血管壁杨氏模量计算装置，其特征在于，所述第二回波信号采集模块，包括：超声辐射力产生子模块和第二回波信号采集子模块；
    所述超声辐射力产生子模块，用于基于所述低频聚焦换能器产生所述聚焦的超声辐射力，以便所述聚焦的超声辐射力作用于所述血管壁产生剪切波，所述剪切波的横向传播引起所述血管壁的纵向位移；
    所述第二回波信号采集子模块，用于在所述剪切波的横向传播引起所述血管壁的纵向位移时，基于所述高频换能器采集所述血管壁在发生所述纵向位移时的所述第二回波信号。
  9. 根据权利要求8所述的血管壁斑块评估装置，其特征在于，所述杨氏模量确定模块，包括：纵向位移计算模块、传播速度确定模块和杨氏模量计算模块；
    所述纵向位移计算模块，用于根据所述第一回波信号和所述第二回波信号，计算所述血管壁的纵向位移；
    所述传播速度确定模块，用于根据所述血管壁的纵向位移和换能器距离，确定所述剪切波的传播速度，其中，所述换能器距离为所述低频聚焦换能器和所述高频换能器的中心距离；
    所述杨氏模量计算模块，用于根据所述剪切波的传播速度和血管壁组织密度，计算所述血管壁的杨氏模量。
  10. 根据权利要求9所述的血管壁斑块评估装置，其特征在于，所述传播速度确定模块，包括：纵向位移峰值确定模块和传播速度计算模块；
    所述纵向位移峰值确定模块，用于根据所述血管壁的纵向位移，确定所述血管壁的纵向位移峰值；
    所述传播速度计算模块，用于根据所述血管壁的纵向位移峰值和所述换能器距离，计算所述剪切波的传播速度。
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