CN114129189B - Dual-frequency intravascular ultrasonic transducer, and method and device for calculating Young modulus of vascular wall - Google Patents
Dual-frequency intravascular ultrasonic transducer, and method and device for calculating Young modulus of vascular wall Download PDFInfo
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- CN114129189B CN114129189B CN202111448283.2A CN202111448283A CN114129189B CN 114129189 B CN114129189 B CN 114129189B CN 202111448283 A CN202111448283 A CN 202111448283A CN 114129189 B CN114129189 B CN 114129189B
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- 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
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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
- A61B8/12—Diagnosis using ultrasonic, sonic or infrasonic waves in body cavities or body tracts, e.g. by using catheters
Abstract
The application provides a dual-frequency intravascular ultrasonic transducer, a method and a device for calculating Young modulus of a vessel wall. The dual-frequency intravascular ultrasonic transducer comprises a low-frequency focusing transducer, wherein the outer surface where a matching layer of the low-frequency focusing transducer is located is inwards recessed to form a spherical concave surface, the spherical concave surface is used for enabling the low-frequency focusing transducer to generate focused ultrasonic radiation force, and the focused ultrasonic radiation force is used for generating shear waves capable of transversely propagating and causing longitudinal displacement of a blood vessel wall in a blood vessel so as to detect the plaque condition of the blood vessel based on the longitudinal displacement of the blood vessel wall. In this application, spherical concave surface makes low frequency focus transducer can produce the ultrasonic radiation power of focus, and the energy of the ultrasonic radiation power of this focus is great to when acting on the vascular wall and producing the shear wave, the transverse propagation of shear wave can arouse the great longitudinal displacement of vascular wall, can accurately detect out the plaque condition of blood vessel based on the great longitudinal displacement of vascular wall.
Description
Technical Field
The application relates to the technical field of medical ultrasound, in particular to a double-frequency intravascular ultrasound transducer and a method and a device for calculating Young modulus of a vessel wall.
Background
At present, there are some dual-frequency transducers for detecting the condition of superficial tissues on the body surface, such as the chest, the abdomen, and the neck, and these dual-frequency transducers usually need to cause the displacement of the tissues based on the ultrasonic radiation force generated by the low-frequency transducer when detecting the superficial tissues on the body surface, then acquire the echo signals when the tissues are displaced by the high-frequency transducer, and perform elastography based on the echo signals, so as to determine whether the superficial tissues have lesions.
However, the existing dual-frequency transducer cannot be used for detecting the vascular plaque condition, and the energy of ultrasonic radiation force generated by the low-frequency transducer is small, so that the caused tissue displacement is not obvious, and the accuracy of the detection result is low.
Disclosure of Invention
In view of this, the present application provides a dual-frequency intravascular ultrasound transducer, a method and an apparatus for calculating a young's modulus of a vascular wall, which are used to solve the problems that the energy of an ultrasound radiation force generated by a low-frequency transducer in the prior art is small and the dual-frequency transducer in the prior art cannot be used to detect a vascular plaque condition, and have the following technical solutions:
a dual-frequency intravascular ultrasound transducer comprising: a low frequency focusing transducer;
the matching layer place surface of low frequency focus transducer is inside sunken, forms spherical concave surface, and spherical concave surface is used for making low frequency focus transducer produce the ultrasonic radiation power of focus, and the ultrasonic radiation power of focus is used for producing the shear wave that can transversely spread the longitudinal displacement that arouses the vascular wall in the blood vessel to longitudinal displacement based on the vascular wall detects the plaque condition of blood vessel.
Optionally, the method further includes: a high frequency transducer and a catheter;
the outer surface of one end of the guide pipe is provided with a pit, the low-frequency focusing transducer and the high-frequency transducer are aligned and assembled in the pit along the extending direction of the guide pipe, and the low-frequency focusing transducer and the high-frequency transducer are connected with the guide pipe through leads welded in the guide pipe;
the other end of the catheter is used for extending into a blood vessel, so that focused ultrasonic radiation force generated by the low-frequency focusing transducer and ultrasonic waves generated by the high-frequency transducer are transmitted into the blood vessel, and echoes generated by the ultrasonic waves in the blood vessel are transmitted back to the high-frequency transducer.
A method for calculating Young modulus of a blood vessel wall is based on the dual-frequency ultrasonic transducer, and comprises the following steps:
after the catheter is inserted into a blood vessel, acquiring a first echo signal when the longitudinal displacement of the blood vessel wall does not occur on the basis of a high-frequency transducer;
acquiring a second echo signal of the vascular wall when the vascular wall is longitudinally displaced on the basis of the low-frequency focusing transducer and the high-frequency transducer;
based on the first echo signal and the second echo signal, a young's modulus of the vessel wall is determined.
Optionally, acquiring a second echo signal of the blood vessel wall when the blood vessel wall is longitudinally displaced based on the low-frequency focusing transducer and the high-frequency transducer, including:
based on the focused ultrasonic radiation force generated by the low-frequency focusing transducer, the focused ultrasonic radiation force acts on the vascular wall to generate shear waves, and the transverse propagation of the shear waves causes the longitudinal displacement of the vascular wall;
when the transverse propagation of the shear wave causes the longitudinal displacement of the blood vessel wall, a second echo signal of the blood vessel wall when the longitudinal displacement occurs is acquired based on the high-frequency transducer.
Optionally, determining the young's modulus of the blood vessel wall based on the first echo signal and the second echo signal includes:
calculating the longitudinal displacement of the blood vessel wall according to the first echo signal and the second echo signal;
determining the propagation speed of the shear wave according to the longitudinal displacement of the blood vessel wall and the distance of the transducer, wherein the distance of the transducer is the central distance between the low-frequency focusing transducer and the high-frequency transducer;
and calculating the Young modulus of the vascular wall according to the propagation speed of the shear wave and the tissue density of the vascular wall.
Optionally, determining the propagation velocity of the shear wave according to the longitudinal displacement of the blood vessel wall includes:
determining a longitudinal displacement peak value of the blood vessel wall according to the longitudinal displacement of the blood vessel wall;
and calculating the propagation speed of the shear wave according to the longitudinal displacement peak value of the blood vessel wall and the distance of the transducer.
A device for calculating young's modulus of a vessel wall based on a dual-frequency ultrasound transducer as described above, comprising: the device comprises a first echo signal acquisition module, a second echo signal acquisition module and a Young modulus determination module;
the first echo signal acquisition module is used for acquiring a first echo signal when the vascular wall does not longitudinally displace based on the high-frequency transducer after the catheter extends into the blood vessel;
the second echo signal acquisition module is used for acquiring a second echo signal of the vascular wall when the vascular wall longitudinally displaces on the basis of the low-frequency focusing transducer and the high-frequency transducer;
and the Young modulus determining module is used for determining the Young modulus of the blood vessel wall based on the first echo signal and the second echo signal.
Optionally, the second echo signal acquiring module includes: the ultrasonic radiation force generation submodule and the second echo signal acquisition submodule are connected;
the ultrasonic radiation force generation submodule is used for generating focused ultrasonic radiation force based on the low-frequency focusing transducer so that the focused ultrasonic radiation force acts on a blood vessel wall to generate shear waves, and the transverse propagation of the shear waves causes the longitudinal displacement of the blood vessel wall;
and the second echo signal acquisition sub-module is used for acquiring a second echo signal of the blood vessel wall when longitudinal displacement occurs on the blood vessel wall based on the high-frequency transducer when the longitudinal displacement of the blood vessel wall is caused by transverse propagation of the shear wave.
Optionally, the young's modulus determining module comprises: the device comprises a longitudinal displacement calculation module, a propagation speed determination module and a Young modulus calculation module;
the longitudinal displacement calculation module is used for calculating the longitudinal displacement of the blood vessel wall according to the first echo signal and the second echo signal;
the propagation velocity determining module is used for determining the propagation velocity of the shear wave according to the longitudinal displacement of the blood vessel wall and the distance of the transducer, wherein the distance of the transducer is the central distance between the low-frequency focusing transducer and the high-frequency transducer;
and the Young modulus calculation module is used for calculating the Young modulus of the vascular wall according to the propagation speed of the shear wave and the tissue density of the vascular wall.
Optionally, the propagation speed determining module includes: the device comprises a longitudinal displacement peak value determining module and a propagation speed calculating module;
the longitudinal displacement peak value determining module is used for determining a longitudinal displacement peak value of the blood vessel wall according to the longitudinal displacement of the blood vessel wall;
and the propagation velocity calculation module is used for calculating the propagation velocity of the shear wave according to the longitudinal displacement peak value of the blood vessel wall and the distance of the transducer.
According to the technical scheme, the dual-frequency intravascular ultrasonic transducer comprises the low-frequency focusing transducer, the outer surface where the matching layer of the low-frequency focusing transducer is located is inwards recessed to form a spherical concave surface, the spherical concave surface is used for enabling the low-frequency focusing transducer to generate focused ultrasonic radiation force, and the focused ultrasonic radiation force is used for generating shear waves which can transversely propagate in a blood vessel to cause longitudinal displacement of a blood vessel wall, so that plaque conditions of the blood vessel can be detected based on the longitudinal displacement of the blood vessel wall. In this application, the spherical concave surface makes low frequency focus transducer can produce the ultrasonic radiation power of focus, and the ultrasonic radiation power's that low frequency transducer among the prior art produced energy of relative ratio, this focused ultrasonic radiation power's energy is great to when acting on the vascular wall production shear wave, the lateral propagation of shear wave can arouse the great longitudinal displacement of vascular wall, can accurately detect out the plaque condition of blood vessel based on the great longitudinal displacement of vascular wall.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of a low frequency transducer included in a dual frequency transducer in the prior art;
FIG. 2 is a schematic structural diagram of a low frequency focusing transducer provided in an embodiment of the present application;
fig. 3 is a schematic structural diagram of a low-frequency focusing transducer, a copper ring and a steel ball provided in 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 of a dual-frequency intravascular ultrasound transducer based control system;
FIG. 6 is a schematic flow chart of a method for calculating Young's modulus of a blood vessel wall according to an embodiment of the present application;
FIG. 7 is a timing diagram of the operation of the low frequency focusing transducer, the high frequency transducer and the motor;
FIG. 8a is a graph of longitudinal displacement of vessel wall over time for a normal isolated porcine coronary;
FIG. 8b is a graph of longitudinal displacement of vessel wall with time after isolated porcine coronary sclerosis;
FIG. 8c is a graph comparing the longitudinal displacement of the blood vessel wall of a normal isolated porcine coronary with the longitudinal displacement of the blood vessel wall of an isolated porcine coronary after hardening;
fig. 9 is a schematic structural diagram of a device for calculating young's modulus of a blood vessel wall according to an embodiment of the present application;
fig. 10 is a block diagram of a hardware structure of a device for calculating a young's modulus of a blood vessel wall according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Atherosclerosis of arteries is characterized by the accumulation of calcium, fibrin, cholesterol, fat and other substances in the intima of large and medium sized arteries, forming plaques, and rupture of this hardened plaque is a major factor in acute cardiovascular events.
In view of the problems that the dual-frequency transducer in the prior art cannot be used for detecting the atherosclerotic plaque condition and the low-frequency transducer in the prior art (see fig. 1, which is a schematic structural diagram of the low-frequency transducer included in the dual-frequency transducer in the prior art and includes a matching layer, a wafer layer and a backing layer) generates relatively small energy of ultrasonic radiation force, after intensive research, the present inventors provide a dual-frequency intravascular ultrasound transducer that includes a low-frequency focusing transducer whose outer surface where the matching layer is located is recessed inward to form a focusing spherical surface. Referring to fig. 2, which is a schematic structural diagram of the low frequency focusing transducer provided in the embodiment of the present application, it can be seen that the matching layer, the wafer layer, and one side of the backing layer close to the wafer layer of the low frequency focusing transducer are all recessed inward.
The spherical concave surface is used for enabling the low-frequency focusing transducer to generate focused ultrasonic radiation force, and the focused ultrasonic radiation force is used for generating shear waves capable of transversely propagating and causing longitudinal displacement of a blood vessel wall in a blood vessel so as to detect plaque conditions of the blood vessel based on the longitudinal displacement of the blood vessel wall.
Particularly, in the embodiment of the present application, the spherical concave surface enables the low-frequency focusing transducer to generate focused ultrasonic radiation force, compare the ultrasonic radiation force energy generated by the low-frequency transducer in the prior art, the focused ultrasonic radiation force energy provided in the embodiment of the present application is large, thereby acting on the vascular wall to generate shear waves, the transverse propagation of the shear waves can cause large longitudinal displacement of the vascular wall, the plaque condition of the blood vessel can be accurately detected based on the large longitudinal displacement of the vascular wall, the problem that the dual-frequency transducer in the prior art cannot be used for detecting the plaque condition of the blood vessel is solved, and the ultrasonic radiation force energy generated by the low-frequency transducer is small, the caused tissue displacement is not obvious, and the problem that the accuracy of the detection result is low is caused.
Optionally, the present application provides a method for manufacturing a low frequency focusing transducer. Referring to fig. 3, a schematic structural diagram of a low-frequency focusing transducer, a copper ring and a steel ball provided in the embodiment of the present application is shown, and a manufacturing process generally includes the following steps: step 1: taking a copper ring with the inner diameter being equal to the size of the unfocused low-frequency transducer, heating to 90 ℃, and soaking with paraffin to ensure that the inside of the copper ring is smooth; step 2: placing the cut unfocused low-frequency transducer in a copper ring and fixing the unfocused low-frequency transducer by filling glue (epoxy resin in figure 3); and step 3: pressing and molding the unfocused low-frequency transducer by using a steel ball in an environment of heating to 90 ℃ to form a low-frequency focusing transducer; and 4, step 4: and taking out the low-frequency focusing transducer from the copper ring, and cutting off glue for fixing the low-frequency focusing transducer.
It should be noted that the above process for manufacturing the low frequency focus transducer is only an example, and is not a limitation on the method for manufacturing the low frequency focus transducer.
On the basis of the low-frequency focusing transducer, the dual-frequency intravascular ultrasound transducer provided by the embodiment of the application can further include: the high-frequency transducer and the catheter, specifically refer to fig. 4, which is a schematic structural diagram of a dual-frequency intravascular ultrasound transducer provided in an embodiment of the present application, and includes a low-frequency focusing transducer 1, a high-frequency transducer 2, and a catheter 3.
In fig. 2, a recess is formed in the outer surface of one end of a guide tube 3, a low frequency focusing transducer 1 and a high frequency transducer 2 are aligned and fitted in the recess in the direction in which the guide tube 1 extends, and both the low frequency focusing transducer 1 and the high frequency transducer 2 are connected to the guide tube 3 by lead wires welded inside the guide tube 3. The other end of the catheter 3 is used for extending 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 is transmitted back to the high-frequency transducer 2.
Specifically, one end of the catheter 3 is a smooth outer surface having a dimple thereon so that the low frequency focusing transducer 1 and the high frequency transducer 2 can be fitted in alignment in the direction in which the catheter 1 extends, and the low frequency focusing transducer 1 and the high frequency transducer 2 can be connected to the catheter 3, respectively, by welding a lead wire inside the catheter 3. The other end of the catheter 3 is an outer surface with threads, and the other end can extend into a blood vessel and freely stretch in the blood vessel so as to detect blood vessel plaques with deep depth.
The catheter 3 has a hollow structure inside, 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 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 high frequency transducer 2.
As described above, the dual-frequency intravascular ultrasound transducer provided by the present application can have two modes of operation, namely, a high-resolution B-mode imaging mode and a high-resolution ultrasound elastography mode.
Wherein in the high resolution B-mode imaging mode the high frequency transducers 2 are operated solely for providing high resolution B-mode image results of the vessel wall. Particularly, in plaque testing process, gather the vascular wall echo signal who corresponds the position through high frequency transducer 2, because high frequency transducer 2 can only gather the vascular wall echo signal of a position at every turn, drive rotatory round through the motor, can gather the echo signal of vascular wall round, that is to say, the intravascular ultrasonic transducer of dual-frenquency that this application embodiment provided can be under the motor drives, gather the echo signal of vascular wall round through high frequency transducer 1, combine the flexible ability of pipe 3 simultaneously, can gather the echo signal of any position department of vascular wall.
For convenience of subsequent description, in the embodiments of the present application, the echo signal is defined as a first echo signal, where the first echo signal is generated without longitudinal displacement of a blood vessel wall, and carries structural information of the blood vessel wall, such as information about stenosis degree of the blood vessel wall, and then a 2D image may be formed by performing envelope detection, log compression, and other processing on the first echo signal (for example, processing through a filter, a data acquisition card, a signal processor, and the like shown in fig. 5), where the 2D image can provide gray scale change information to calculate structural information of the blood vessel wall, and provide real-time data for subsequent other analysis.
Under the high resolution supersound elasticity imaging mode, low frequency focus transducer 1 is as exciting transducer, and high frequency transducer 2 is as detecting the transducer, and low frequency focus transducer 1 and high frequency transducer 2 work simultaneously for detect the longitudinal displacement of vascular wall. Specifically, referring to a connection relation diagram of a control system based on a dual-frequency intravascular ultrasound transducer shown in fig. 5, firstly, a sinusoidal signal of 100 μ s to 500 μ s is output by a signal generator, and the signal is amplified to a higher voltage by a power amplifier for exciting the low-frequency focused transducer 1, compared with the high-frequency transducer 2 and an unfocused transducer in the prior art, the low-frequency focused transducer 1 can generate a focused ultrasound radiation force with higher energy, and the focused ultrasound radiation force acts on a blood vessel wall to generate shear waves, so that the blood vessel wall generates longitudinal displacement; 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 high-resolution echo signals are acquired through oversampling.
For convenience of subsequent description, in the embodiments of the present application, the high-resolution echo signal is defined as a second echo signal, where the second echo signal is generated when the blood vessel wall longitudinally displaces, and carries information about the longitudinal displacement of the blood vessel wall, and then biomechanical information, such as 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.
In order to make those skilled in the art understand how the young's modulus of the blood vessel wall is calculated in the present application, the method for calculating the young's modulus of the blood vessel wall provided in the embodiments of the present application is described in detail below.
Referring to fig. 6, a schematic flow chart of a method for calculating a young's modulus of a blood vessel wall provided in an embodiment of the present application is shown, where the method for calculating a young's modulus of a blood vessel wall may be based on the dual-frequency ultrasonic transducer, and optionally, the method for calculating a young's modulus of a blood vessel wall may include:
step S601, after the catheter is inserted into a blood vessel, acquiring a first echo signal when the longitudinal displacement of the blood vessel wall does not occur on the basis of the high-frequency transducer.
See figure 7 for a timing diagram of the operation of the low frequency focus transducer, the high frequency transducer and the motor. Within the first 100 mus, the dual-frequency intravascular ultrasound transducer is in a high-resolution B-mode imaging mode, the high-frequency transducer 2 (detection transducer) works independently, and after the catheter 3 goes deep into the blood vessel, the high-frequency transducer 1 can acquire a first echo signal when the blood vessel wall does not longitudinally displace.
And step S602, acquiring a second echo signal of the blood vessel wall when the blood vessel wall is longitudinally displaced based on the low-frequency focusing transducer and the high-frequency transducer.
Optionally, the process of this step may specifically include: based on the focused ultrasonic radiation force generated by the low-frequency focusing transducer, the focused ultrasonic radiation force acts on the vascular wall to generate shear waves, and the transverse propagation of the shear waves causes the longitudinal displacement of the vascular wall; when the transverse propagation of the shear wave causes the longitudinal displacement of the blood vessel wall, a second echo signal of the blood vessel wall when the longitudinal displacement occurs is acquired based on the high-frequency transducer.
Specifically, still referring to fig. 7, within 100 μ s to 20ms, 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 transducer) operate simultaneously, wherein the low-frequency focusing transducer 1 only needs to operate for 200 μ s, within 200 μ s, the low-frequency focusing transducer 1 can generate focused ultrasound radiation force, the focused ultrasound radiation force acts on the blood vessel wall to generate shear waves, and the transverse propagation of the shear waves causes the longitudinal displacement of the blood vessel wall. The high frequency transducer 2 needs to be operated at all times to acquire the second echo signal of the vessel wall at the time of longitudinal displacement when the longitudinal displacement of the vessel wall is caused by the lateral propagation of the shear wave.
Afterwards, the motor can drive the intravascular ultrasonic transducer of dual-frenquency and rotate, 200ms back, gather the first echo signal and the second echo signal of the position department after the rotation according to above-mentioned process, so repeatedly, just can gather the first echo signal and the second echo signal of vascular wall round.
Step S603 of determining the young' S modulus of the blood vessel wall based on the first echo signal and the second echo signal.
In this step, first echo signal and second echo signal can be used to calculate the young modulus of vascular wall, and this young modulus can reflect the soft or hard degree of vascular wall, can audio-visually distinguish normal vascular wall and plaque (pathological change vascular wall) according to the young modulus size of difference, distinguishes the plaque of different natures simultaneously to can accurately assess atherosclerosis disease.
Optionally, the process of calculating the young's modulus of the blood vessel wall in this step may include:
s1, calculating the longitudinal displacement of the blood vessel wall according to the first echo signal and the second echo signal.
Specifically, in this step, the difference between the first echo signal and the second echo signal may be calculated by a normalized cross-correlation algorithm, so as to obtain the longitudinal displacement of the blood vessel wall caused by the shear wave.
Alternatively, the longitudinal displacement of the vessel wall may be calculated according to the following formula:
wherein c (j) is the longitudinal displacement of the vessel wall, f r 、f s Respectively a first echo signal and a second echo signal,
the average values of the first echo signal and the second echo signal are respectively, and M is the size of a sampling window.
In order to verify the feasibility and the effectiveness of the application, the formalin-soaked Lin Qiande isolated pig coronary artery is used for simulating a normal blood vessel wall, the formalin-soaked isolated pig coronary artery is used for simulating the hard plaque blood vessel wall, and the detection result can be seen in fig. 8, (a) is a graph showing that the longitudinal displacement of the blood vessel wall of the normal isolated pig coronary artery changes along with time, (b) is a graph showing that the longitudinal displacement of the blood vessel wall of the isolated pig coronary artery changes along with time, and (c) is a comparison between the graph and the graph, so that the application can detect the longitudinal displacement of the blood vessel wall caused by shear waves, and can distinguish the normal blood vessel wall and the lesion blood vessel wall with different hardness.
And S2, determining the propagation speed of the shear wave according to the longitudinal displacement of the blood vessel wall and the distance of the transducer, wherein the distance of the transducer is the central distance between the low-frequency focusing transducer and the high-frequency transducer.
Optionally, the process of this step may include the following steps:
and S21, determining a longitudinal displacement peak value of the blood vessel wall according to the longitudinal displacement of the blood vessel wall.
As seen from S1, the longitudinal displacement of the blood vessel wall is a time-varying amount, and thus the peak value of the longitudinal displacement of the blood vessel wall can be determined.
And S22, calculating the propagation speed of the shear wave according to the longitudinal displacement peak value of the blood vessel wall and the distance of the transducer.
Alternatively, it can be represented by the formula v sw ＝d e /t p And calculating the propagation speed of the shear wave.
In the formula, v sw Is the propagation velocity of the shear wave, d e Is the center distance, t, of the high frequency transducer 2 and the low frequency focus transducer p The peak value of the longitudinal displacement of the blood vessel wall is calculated by a normalized cross-correlation algorithm.
And S3, calculating the Young modulus of the vascular wall according to the propagation speed of the shear wave and the tissue density of the vascular wall.
In particular, the shear wave propagation velocity v is calculated sw Then, the vessel wall young's modulus E can be calculated by using the vessel wall tissue density ρ.
Alternatively, by formula
The young's modulus of the vessel wall was calculated.
The method for calculating the Young's modulus of the vascular wall provided by the application utilizes the dual-frequency intravascular ultrasonic transducer to estimate the Young's modulus of the vascular wall from the measured longitudinal displacement and the longitudinal displacement peak value of the vascular wall, the Young's modulus parameter has definite physical significance and is closely related to the plaque breakage easiness degree.
The embodiment of the present application further provides a device for calculating a young's modulus of a vascular wall, which is described below, and the device for calculating a young's modulus of a vascular wall described below and the method for calculating a young's modulus of a vascular wall described above may be referred to in correspondence.
Referring to fig. 9, a schematic structural diagram of a device for calculating a young's modulus of a blood vessel wall according to an embodiment of the present application is shown, and as shown in fig. 9, the device for calculating a young's modulus of a blood vessel wall may include: a first echo signal acquisition module 901, a second echo signal acquisition module 902 and a young's modulus determination module 903.
The first echo signal acquisition module 901 is configured to acquire, based on the high-frequency transducer, a first echo signal when a blood vessel wall does not longitudinally displace after the catheter is inserted into the blood vessel.
And a second echo signal acquiring module 902, configured to acquire a second echo signal of the vascular wall when a longitudinal displacement occurs on the basis of the low-frequency focusing transducer and the high-frequency transducer.
A young's modulus determination module 903 for determining a young's modulus of the vessel wall based on the first echo signal and the second echo signal.
In a possible implementation manner, the second echo signal acquiring module 902 may include: the ultrasonic radiation force generation sub-module and the second echo signal acquisition sub-module.
The ultrasonic radiation force generation submodule is used for generating focused ultrasonic radiation force based on the low-frequency focusing transducer, so that the focused ultrasonic radiation force acts on a blood vessel wall to generate shear waves, and the transverse propagation of the shear waves causes the longitudinal displacement of the blood vessel wall.
And the second echo signal acquisition sub-module is used for acquiring a second echo signal of the blood vessel wall when longitudinal displacement occurs on the blood vessel wall based on the high-frequency transducer when the longitudinal displacement of the blood vessel wall is caused by transverse propagation of the shear wave.
In one possible implementation, the young's modulus determining module may include: the device comprises a longitudinal displacement calculation module, a propagation speed determination module and a Young modulus calculation module.
And the longitudinal displacement calculation module is used for calculating the longitudinal displacement of the blood vessel wall according to the first echo signal and the second echo signal.
And the propagation velocity determining module is used for determining the propagation velocity of the shear wave according to the longitudinal displacement of the blood vessel wall and the distance of the transducer, wherein the distance of the transducer is the central distance between the low-frequency focusing transducer and the high-frequency transducer.
And the Young modulus calculation module is used for calculating the Young modulus of the blood vessel wall according to the propagation speed of the shear wave and the tissue density of the blood vessel wall.
In a possible implementation manner, the propagation speed determining module may include: a longitudinal displacement peak value determining module and a propagation velocity calculating module.
The longitudinal displacement peak value determining module is used for determining the longitudinal displacement peak value of the blood vessel wall according to the longitudinal displacement of the blood vessel wall.
And the propagation velocity calculation module is used for calculating the propagation velocity of the shear wave according to the longitudinal displacement peak value of the blood vessel wall and the distance of the transducer.
The embodiment of the application further provides a device for calculating the Young modulus of the vascular wall. Alternatively, fig. 10 shows a block diagram of a hardware structure of the young's modulus calculation device for the blood vessel wall, and referring to fig. 10, the hardware structure of the young's modulus calculation device for the 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;
in the embodiment of the present application, the number of the processor 1001, the communication interface 1002, the memory 1003, and the communication bus 1004 is at least one, and the processor 1001, the communication interface 1002, and the memory 1003 complete communication with each other through the communication bus 1004;
the processor 1001 may be a central processing unit CPU, or an Application Specific Integrated Circuit ASIC (Application Specific Integrated Circuit), or one or more Integrated circuits configured to implement embodiments of the present invention, etc.;
the memory 1003 may include a high-speed RAM memory, and may further include a non-volatile memory (non-volatile memory) or the like, such as at least one disk memory;
wherein, the memory 1003 stores a program, and the processor 1001 may call the program stored in the memory 1003, where the program is used to:
after the catheter is stretched into a blood vessel, acquiring a first echo signal when the longitudinal displacement of the blood vessel wall does not occur on the basis of a high-frequency transducer;
acquiring a second echo signal of the vascular wall when the vascular wall is longitudinally displaced on the basis of the low-frequency focusing transducer and the high-frequency transducer;
based on the first echo signal and the second echo signal, a young's modulus of the vessel wall is determined.
Alternatively, the detailed function and the extended function of the program may be as described above.
The embodiment of the 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 method for calculating the young's modulus of the vascular wall is realized.
Alternatively, the detailed function and the extended function of the program may be as described above.
Finally, it is further noted that, herein, relational terms such as, for example, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A dual-frequency intravascular ultrasound transducer, comprising: a low frequency focusing transducer, a high frequency transducer, and a catheter;
the outer surface of the low-frequency focusing transducer where the matching layer is located is inwards recessed to form a spherical concave surface, the spherical concave surface is used for enabling the low-frequency focusing transducer to generate focused ultrasonic radiation force, and the focused ultrasonic radiation force is used for generating shear waves capable of transversely propagating to cause longitudinal displacement of a blood vessel wall in a blood vessel so as to detect plaque conditions of the blood vessel based on the longitudinal displacement of the blood vessel wall;
wherein the low frequency focusing transducer is formed by the following method:
taking a copper ring with the inner diameter being equal to the size of the unfocused low-frequency transducer, heating to 90 ℃, and infiltrating with paraffin; placing the cut unfocused low-frequency transducer in a copper ring, and filling glue to fix the unfocused low-frequency transducer; pressing and molding the unfocused low-frequency transducer by using a steel ball in an environment of heating to 90 ℃ to form a low-frequency focusing transducer;
wherein the content of the first and second substances,
a pit is formed on the outer surface of one end of the guide pipe, the low-frequency focusing transducer and the high-frequency transducer are aligned and assembled in the pit along the extending direction of the guide pipe, and the low-frequency focusing transducer and the high-frequency transducer are connected with the guide pipe through leads welded in the guide pipe;
the other end of the catheter is used for extending 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 high-frequency transducer.
2. A vessel wall young's modulus calculation method based on the dual-frequency intravascular ultrasound transducer of claim 1, comprising:
acquiring a first echo signal based on the high frequency transducer when the longitudinal displacement of the vessel wall does not occur after the catheter is inserted into the vessel;
acquiring a second echo signal of the blood vessel wall when the longitudinal displacement occurs based on the low frequency focusing transducer and the high frequency transducer;
determining a Young's modulus of the vessel wall based on the first echo signal and the second echo signal.
3. The method for calculating young's modulus of a blood vessel wall according to claim 2, wherein said acquiring a second echo signal of the blood vessel wall when the longitudinal displacement occurs based on the low frequency focusing transducer and the high frequency transducer comprises:
generating the focused ultrasonic radiation force based on the low frequency focusing transducer such that the focused ultrasonic radiation force acts on the vessel wall to generate shear waves, lateral propagation of the shear waves causing longitudinal displacement of the vessel wall;
acquiring the second echo signal of the vessel wall at the occurrence of the longitudinal displacement based on the high frequency transducer when the longitudinal displacement of the vessel wall is caused by the lateral propagation of the shear wave.
4. The method for calculating the young's modulus of the vascular wall according to claim 3, wherein the determining the young's modulus of the vascular wall based on the first echo signal and the second echo signal includes:
calculating the longitudinal displacement of the blood vessel wall according to the first echo signal and the second echo signal;
determining the propagation speed of the shear wave according to the longitudinal displacement of the blood vessel wall and a transducer distance, wherein the transducer distance is the central distance of the low-frequency focusing transducer and the high-frequency transducer;
and calculating the Young modulus of the blood vessel wall according to the propagation speed of the shear wave and the tissue density of the blood vessel wall.
5. The method for calculating the young's modulus of the vascular wall according to claim 4, wherein the determining the propagation velocity of the shear wave according to the longitudinal displacement of the vascular wall includes:
determining a longitudinal displacement peak value of the blood vessel wall according to the longitudinal displacement of the blood vessel wall;
and calculating the propagation speed of the shear wave according to the longitudinal displacement peak value of the blood vessel wall and the transducer distance.
6. A vessel wall young's modulus calculation device based on the dual-frequency intravascular ultrasound transducer of claim 1, comprising: the device comprises a first echo signal acquisition module, a second echo signal acquisition module and a Young modulus determination module;
the first echo signal acquisition module is used for acquiring a first echo signal when the blood vessel wall does not generate the 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 for acquiring a second echo signal of the blood vessel wall when the longitudinal displacement occurs on the basis of the low-frequency focusing transducer and the high-frequency transducer;
the young modulus determination module is used for determining the young modulus of the blood vessel wall based on the first echo signal and the second echo signal.
7. The apparatus for calculating young's modulus of a vascular wall according to claim 6, wherein the second echo signal acquiring module comprises: the ultrasonic radiation force generation submodule and the second echo signal acquisition submodule are connected;
the ultrasonic radiation force generation sub-module is used for generating the focused ultrasonic radiation force based on the low-frequency focusing transducer so that the focused ultrasonic radiation force acts on the blood vessel wall to generate a shear wave, and the transverse propagation of the shear wave causes the longitudinal displacement of the blood vessel wall;
the second echo signal acquisition submodule is used for acquiring the second echo signal of the blood vessel wall when the longitudinal displacement of the blood vessel wall occurs on the basis of the high-frequency transducer when the transverse propagation of the shear wave causes the longitudinal displacement of the blood vessel wall.
8. The vessel wall young's modulus calculation device of claim 7, wherein the young's modulus determination module comprises: the system comprises a longitudinal displacement calculation module, a propagation speed determination module and a Young modulus calculation module;
the longitudinal displacement calculation module is used for calculating the longitudinal displacement of the blood vessel wall according to the first echo signal and the second echo signal;
the propagation velocity determining module is used for determining the propagation velocity of the shear wave according to the longitudinal displacement of the blood vessel wall and the transducer distance, wherein the transducer distance is the central distance between the low-frequency focusing transducer and the high-frequency transducer;
and the Young modulus calculation module is used for calculating the Young modulus of the vascular wall according to the propagation speed of the shear wave and the tissue density of the vascular wall.
9. The vessel wall young's modulus calculation device of claim 8, wherein the propagation velocity determination module comprises: the device comprises a longitudinal displacement peak value determining module and a propagation speed calculating module;
the longitudinal displacement peak value determining module is used for determining a longitudinal displacement peak value of the blood vessel wall according to the longitudinal displacement of the blood vessel wall;
and the propagation velocity calculation module is used for calculating the propagation velocity of the shear wave according to the longitudinal displacement peak value of the blood vessel wall and the distance of the transducer.
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| CN202111448283.2A CN114129189B (en) | 2021-11-30 | 2021-11-30 | Dual-frequency intravascular ultrasonic transducer, and method and device for calculating Young modulus of vascular wall |
| PCT/CN2021/138042 WO2023097781A1 (en) | 2021-11-30 | 2021-12-14 | Dual-frequency intravascular ultrasonic transducer and method and device used to calculate young modulus of blood vessel wall |
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| CN202111448283.2A CN114129189B (en) | 2021-11-30 | 2021-11-30 | Dual-frequency intravascular ultrasonic transducer, and method and device for calculating Young modulus of vascular wall |
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| CN102667522B (en) * | 2009-11-25 | 2014-10-08 | 皇家飞利浦电子股份有限公司 | Ultrasonic shear wave imaging with focused scanline beamforming |
| CN101912278A (en) * | 2010-08-12 | 2010-12-15 | 陈庆武 | Ultrasound dynamic elastic imaging probe and method |
| CN104055541A (en) * | 2014-06-26 | 2014-09-24 | 中国科学院苏州生物医学工程技术研究所 | Method for intravascular ultrasound multi-slice shear wave elastography |
| KR20170005526A (en) * | 2015-06-23 | 2017-01-16 | 서강대학교산학협력단 | An ultrasound transducer assembly for beam-forming and manufacturing method thereof |
| CN105105791B (en) * | 2015-09-02 | 2018-01-16 | 上海爱声生物医疗科技有限公司 | A kind of intravascular ultrasound focus method, focused diagnostic instrument and focused transducer |
| CN107423464A (en) * | 2016-12-10 | 2017-12-01 | 清华大学 | Determine the method and system of the elastic parameter of fluid line wall |
| CN107260216B (en) * | 2017-06-22 | 2023-09-19 | 苏州国科昂卓医疗科技有限公司 | Ultrasonic endoscopic probe and elastic imaging system and method |
| CN108593783B (en) * | 2017-11-16 | 2021-01-01 | 浙江大学 | Dual-frequency confocal ultrasonic transducer |
| CN107981887B (en) * | 2017-12-19 | 2020-06-16 | 深圳先进技术研究院 | Ultrasonic transducer, focusing transducer and manufacturing method of focusing transducer |
| JP7052530B2 (en) * | 2018-04-25 | 2022-04-12 | コニカミノルタ株式会社 | Ultrasonic diagnostic equipment and ultrasonic signal processing method |
| CN110141268A (en) * | 2019-05-07 | 2019-08-20 | 天津大学 | A kind of machinery rotating type double frequency intravascular ultrasound radiant force elastic imaging probe |
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