A method for measuring a blood vessel wall cutting parameter, an electronic device, and a storage medium

Abstract

The application provides a blood vessel wall shear parameter measurement method, an electronic device and a storage medium. The blood vessel wall shear parameter measurement method comprises the following steps: obtaining THG images of two different positions on the equatorial plane of a blood vessel to be measured in the blood flow direction, wherein the THG images comprise a first THG image corresponding to a first position and a second THG image corresponding to a second position, the first position is close to the wall of the blood vessel to be measured, the second position is between the first position and the center line of the equatorial plane, and the first position and the second position are both located on the same perpendicular line of the center line; obtaining a first instantaneous blood flow velocity at the first position according to the first THG image, and obtaining a second instantaneous blood flow velocity at the second position according to the second THG image; and calculating an instantaneous wall shear rate of the blood vessel to be measured according to the first instantaneous blood flow velocity and the second instantaneous blood flow velocity. The application has a sub-micron spatial resolution, does not need to inject exogenous fluorescent beads, and can measure the instantaneous value of the blood vessel wall shear parameter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of measuring blood vessel wall shear parameters, and particularly relates to a blood vessel wall shear parameter measurement method, an electronic device and a storage medium. BACKGROUND

[0002] During the systemic circulation, the blood of human and animal exerts a stress on the blood vessel wall which is tangential to the direction of blood flow, called blood vessel wall shear stress (for short, blood vessel wall shear stress), denoted as τ = μγ = μ·(dv / dr); wherein, τ is blood vessel wall shear stress, μ is blood viscosity, γ is blood vessel wall shear rate (for short, blood vessel wall shear rate), and dv / dr is blood vessel wall axial velocity gradient (i.e. blood vessel wall shear rate).

[0003] As the main form of blood vessel wall shear parameters, blood vessel wall shear stress and blood vessel wall shear rate have great significance in physiology and pathology. Generally, endothelial cells respond to blood vessel wall shear stress by changing their morphology, function and gene expression, and abnormal blood vessel wall shear stress promotes the development of atherosclerosis and inflammation, and it also reflects many vascular conditions (such as atherosclerotic lesions, ruptured aneurysms and cerebral arteriovenous malformations, etc.), thus making it a focus of theoretical and experimental research. In the theoretical aspect, on the one hand, a simple model is established to regard blood flow as a fully developed Newtonian fluid in a cylindrical tube (equivalent to a blood vessel), and on the other hand, a more advanced and complex computational fluid model is established to consider the blood composition and blood vessel geometry. In the experimental aspect, blood vessel wall shear stress has been measured and studied in vivo in human experimental subjects, in animal models and in vitro fluid devices simulating blood flow.

[0004] In the related art, on a macroscopic level, ultrasound imaging and phase-contrast magnetic resonance imaging have been successfully applied to measure the wall shear parameter of a living animal or even a human body. However, the low spatial resolution of these measurement methods limits the measurement position to a position far from the blood vessel wall (for example, a position 100-1000 μm away from the blood vessel wall), thereby resulting in low measurement accuracy of the wall shear parameter. On a microscopic level, a commonly used measurement method is to perform optical imaging and tracking on fluorescent beads circulating in the blood to draw a blood flow velocity close to the blood vessel wall. This method relies on the high spatial resolution (micron level) of optical imaging, and the measurement position is closer to the blood vessel wall, thereby resulting in higher measurement accuracy of the wall shear parameter than ultrasound imaging and phase-contrast magnetic resonance imaging. However, this measurement method of tracking fluorescent beads still has many drawbacks, such as: 1. The need to inject exogenous fluorescent beads to generate fluorescence contrast, which is not suitable for human measurement; 2. The flow of the fluorescent beads in the field of view is random, and the distance between the fluorescent beads and the blood vessel wall is also random. Essentially, only the average value of the wall shear parameter can be measured, and the instantaneous value cannot be measured; and 3. For fluorescent bead tracking based on wide-field fluorescence imaging, the out-of-focus fluorescence makes the axial position of the fluorescent bead more complex, and the fluorescence profile of the fluorescent bead needs to be considered for complex correction.

[0005] Therefore, it is necessary to improve the measurement method of the wall shear parameter. SUMMARY

[0006] The present application provides a measurement method of a wall shear parameter, an electronic device and a storage medium, aiming at solving the problems of low spatial resolution, the need for exogenous fluorescent bead injection and the inability to measure the instantaneous value when measuring the wall shear parameter in the related art.

[0007] To solve the above technical problems, the first aspect of the embodiments of the present application provides a measurement method of a wall shear parameter, comprising:

[0008] Obtaining a THG image of a blood vessel to be measured in a blood flow direction at two different positions on an equatorial plane of the blood vessel to be measured; wherein the THG image comprises a first THG image corresponding to a first position and a second THG image corresponding to a second position, the first position is close to the wall of the blood vessel to be measured, the second position is located between the first position and a center line of the equatorial plane, and the first position and the second position are located on the same perpendicular line of the center line;

[0009] According to the first THG image, a first instantaneous blood flow velocity at the first position is obtained, and according to the second THG image, a second instantaneous blood flow velocity at the second position is obtained;

[0010] According to the first instantaneous blood flow velocity and the second instantaneous blood flow velocity, an instantaneous wall shear rate of the blood vessel to be measured is calculated.

[0011] The second aspect of the embodiments of the present application provides an electronic device, comprising a storage device and at least one processor; the storage device is used for storing at least one program, and when the at least one program is executed by the at least one processor, the at least one processor executes the method in the first aspect of the embodiments of the present application.

[0012] The third aspect of the embodiments of the present application provides a computer readable storage medium, and the computer readable storage medium stores executable instructions, and the executable instructions are executed to execute the method in the first aspect of the embodiments of the present application.

[0013] From the above description, compared with the related art, the beneficial effects of the present application are that:

[0014] The first THG image of the first position on the equatorial plane of the blood vessel to be measured is acquired by linear scanning in the blood flow direction, and the second THG image of the second position on the equatorial plane of the blood vessel to be measured is acquired by linear scanning in the blood flow direction; the first instantaneous blood flow velocity at the first position is obtained according to the first THG image, and the second instantaneous blood flow velocity at the second position is obtained according to the second THG image; the instantaneous wall shear rate of the blood vessel to be measured is calculated according to the first instantaneous blood flow velocity and the second instantaneous blood flow velocity. As can be seen, the present application is realized based on third harmonic (THG) imaging, which belongs to a common way of multi-photon microscopy. Compared with ultrasonic imaging and phase contrast magnetic resonance imaging, it has a sub-micron spatial resolution, does not need to inject exogenous fluorescent beads, belongs to a kind of label-free measurement scheme, and has inherent three-dimensional slicing capability, and does not appear signal defocusing phenomenon, can measure the instantaneous value of the blood vessel wall shear parameter, and has higher measurement precision. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the related art or the embodiments of the present application, the drawings needed to be used in the description of the related art or the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and not all embodiments. Those skilled in the art can obtain other drawings according to these drawings without creating any creative labor.

[0016] Figure 1 The principle diagram of the blood vessel wall shear parameter measurement method provided by the embodiments of the present application is shown in the figure;

[0017] Figure 2 The selection of the equatorial plane of the blood vessel to be measured and the linear scanning of the two different positions thereon are shown in the figure;

[0018] Figure 3A schematic diagram of blood viscosity fitting provided for an embodiment of this application;

[0019] Figure 4 THG imaging and blood flow velocity map of mouse cerebral blood vessels provided in the embodiments of this application;

[0020] Figure 5 THG imaging and blood flow velocity map of human cerebral blood vessels provided in the embodiments of this application;

[0021] Figure 6 The experimental results of blood vessel wall shear rate and stress provided in the embodiments of this application are shown in the figure.

[0022] Figure 7 A schematic flowchart illustrating the method for measuring blood vessel wall shear parameters provided in an embodiment of this application;

[0023] Figure 8 A module block diagram of the electronic device provided in the embodiments of this application;

[0024] Figure 9 A block diagram of a computer-readable storage medium provided in an embodiment of this application.

Detailed Implementation Methods

[0025] To make the objectives, technical solutions, and advantages of this application more apparent and understandable, the application will be clearly and completely described below in conjunction with the embodiments and corresponding drawings. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. It should be understood that the various embodiments of this application described below are merely illustrative and not intended to limit the application. That is, all other embodiments obtained by those skilled in the art based on the various embodiments of this application without creative effort are within the scope of protection of this application. Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0026] This application utilizes the third harmonic signal generated by blood vessels and red blood cells after laser excitation, and employs THG microscopy to measure the shear rate and shear force of the blood vessel wall without labeling. The optical path diagram used is as follows. Figure 1A. As shown in FIG. 1, dual-wavelength femtosecond excitation laser pulses are generated by polarization-multiplexed soliton self-frequency shift in a large-mode-area (LMA) polarization maintaining fiber. A 6.25 MHz linearly polarized femtosecond pump laser at 1550 nm is coupled into a 3 m long LMA fiber with its polarization axis at an angle to the fast axis of the LMA fiber. A half-wave plate (HWP) is adjusted to split the pump pulses into two orthogonally polarized pulses along the fast and slow axes of the LMA fiber, each of which propagates in the LMA fiber and generates its own displaced soliton. A custom-made 1650 nm long-pass filter (F1) is used to remove the stray light at the output end of the LMA fiber. Then, a polarizing beam splitter (PBS) is used to spatially separate the two wavelengths, and the two beams are adjusted by three mirrors (M2, M3, M4) to be perpendicular to each other and focused on an x-scan mirror (x-Mirror). The excitation beams of the two wavelengths are then expanded by a 1:4 beam expander consisting of a scan lens (SL) and a tube lens (TL) in a multi-photon microscope (MOM), and then focused onto the sample by a custom-made water-immersion objective with a working distance of 2 mm, which is immersed in heavy water (D2O) to maximize its transmittance. At the signal collection end, the THG signals excited by the two wavelengths are first separated by dichroic mirrors (DC1, DC2), and then detected by photomultiplier tubes (PMT1, PMT2) with band-pass filters (F2, F3, 630 / 92 and 540 / 80, respectively) for the THG signals excited by the 1780 nm and 1680 nm wavelengths, respectively.

[0027] wherein, Figure 1 A. (b) shows the basic principle of measuring the shear rate. The instantaneous shear rate γ = |(v2-v1) / (r2-r1)| is measured by measuring the instantaneous flow velocities (v1, v2) at two radial positions (r1, r2) close to the vessel wall. v1 and v2 are measured simultaneously by dual-wavelength line-scan THG imaging. Dual-wavelength femtosecond excitation laser pulses at wavelengths λ1 and λ2 are focused and line-scanned at radial positions r1 and r2, respectively. The red blood cells flowing past r1 and r2 after excitation generate third harmonics at λ1 / 3 and λ2 / 3, respectively. These harmonic signals are detected simultaneously to produce line-scan traces from which v1 and v2 can be measured.

[0028] Figure 1The measured soliton spectra are shown in FIG. 1.B, with peak wavelengths of 1680 nm and 1780 nm, and pulse widths of 98.1 fs and 94.9 fs, respectively. To characterize the spatial resolution, we measured the point spread functions (PSFs) by imaging 0.5-μm fluorescent beads embedded in agarose via three-photon fluorescence (3PF). The measured lateral and axial 3PF curves are shown in FIG. 1.C. Assuming a Gaussian spatial beam profile, the deconvolved lateral PSFs are 0.40 μm and 0.44 μm, and the axial PSFs are 1.96 μm and 1.93 μm for 1680 nm and 1780 nm, respectively. Figure 1

[0029] Measuring blood flow velocity:

[0030] The equatorial plane of the blood vessel was determined using the three-dimensional slicing capability of the MPM. First, the target blood vessel was imaged by 3D stack imaging via THG imaging, from which the upper and lower boundaries of the blood vessel with flowing red blood cells could be identified (FIG. 2.A). Then the focal plane was shifted to the middle plane between the upper and lower boundaries, i.e., the equatorial plane of the blood vessel as shown in the two-dimensional image (FIG. 2.B). Figure 2 Figure 2

[0031] On this determined equatorial plane, one-dimensional line-scan THG imaging was performed continuously in parallel to the vessel wall and recorded. The scanning line was shifted from the outside to the inside of the blood vessel until there were signals from both channels (i.e., the two wavelengths of excitation light described above). Representative line-scan traces for both excitation wavelengths are shown in FIG. 3.A and FIG. 3.B. As can be seen, as the scanning line enters the blood vessel, tilted stripes appear in the third harmonic image, which reflects the flow of red blood cells along the scanning line. The time-varying slope of the tilted stripes is the instantaneous blood flow velocity. Figure 2

[0032] We chose the first radial position of the tilted stripes for the excitation light λ1scanning imaging to be r1, then the scanning position for the excitation light λ2was r2= r1- 5 μm, which is closer to the centerline of the blood vessel. Since the THG line-scan traces were acquired simultaneously for both excitation wavelengths, the blood flow velocities at r1and r2could be measured simultaneously, from which the instantaneous shear rate and WSS (wall shear stress) could be measured. In all measurements, the scanning rate was kept at 1 KHz.

[0033] Calculating the shear rate and shear stress of the blood vessel wall:

[0034] ​​​​WSS is mathematically expressed as τ = μγ = μ · (dv / dr), where τ is the wall shear stress, μ is the blood viscosity, γ is the wall shear rate, and dv / dr is the axial velocity gradient of the blood flow (i.e. the wall shear rate). Here, the instantaneous shear rate is calculated as γ = |(v2-v1) / (r2-r1)|, and since the diameter of the red blood cell is about 5 μm, the optical path is adjusted so that the imaging results of the two beams are longitudinally separated by 5 μm, i.e. r1-r2 = 5 μm in the formula.

[0035] In the simplest case, blood is assumed to be a Newtonian fluid, and μ is a constant. However, many studies have shown that blood is by no means a Newtonian fluid, and therefore μ is not a constant but depends on the shear rate γ. In related experiments, the blood viscosity under different shear rates of different species can be accurately measured, and different rheological models have been proposed to explain this non-Newtonian fluid behavior of blood. Here, the Quemada model is used to calculate the relationship between the shear rate and the blood viscosity μ, which has been experimentally verified and applied to computational fluid dynamics. In this model, the instantaneous wall shear rate and the blood viscosity have the following relationship:

[0036] μ = η p [1-0.5k Q ·Hct] -2 ,

[0037]

[0038] where η p represents the plasma viscosity, Hct represents the hematocrit, k0 represents the maximum volume fraction when the wall shear rate is zero, k ∞ represents the maximum volume fraction under infinite wall shear rate, γ' represents the characteristic rate of red blood cell string formation / degradation, and μ represents the blood viscosity. For this, after measuring the viscosity values of mice under different shear rates, we use the Quemada model to fit these measured viscosities (as shown in Figure 3 ), determine the parameters in the model to obtain the calculated relationship between the shear rate and the viscosity, i.e. the corresponding viscosity coefficient can be obtained by calculation when the flow rate is measured. Therefore, it can be summarized that measuring WSS only requires measuring the wall shear rate γ.

[0039] Measurement and calculation results:

[0040] According to the above measurement method, we measured the blood flow rate of the brain blood vessels (small venules and small arteries) of live mice, and calculated the wall shear rate and shear force of the blood vessels.

[0041] First, the small venules and small arteries are determined by the direction of blood flow, then the dual-wavelength THG imaging is performed, and the instantaneous velocity of two adjacent radial positions is measured. Figure 4A. (a) shows THG images of a 1780 nm excited small vein with a diameter of 37 μm, where the arrow indicates the blood flow direction and the boxed vessel cross-section is where THG images under 1680 nm and 1780 nm excitation are obtained Figure 4 A. (b), Figure 4 A. (c) show longitudinal separation of 5 μm. Figure 4 B. (a) and Figure 4 B. (b) are THG line scan traces collected simultaneously near the upper vessel wall, and THG line scan traces near the lower vessel wall are shown in Figure 4 B. (d) and Figure 4 B. (e).

[0042] This dual-wavelength line-scan THG imaging can also be applied to small arteries in the brain. Figure 5 For a measured small artery with a diameter of 40 μm, the arrow indicates the blood flow direction. Compared with the small vein in Figure 4 , the blood flow velocity near the vessel wall is faster Figure 5 B. (c), Figure 5 B. (f). The average and peak-to-peak values of the flow velocity are summarized in the table below.

[0043]

[0044] Figure 6 The calculated shear rate and shear stress of the vessels are shown. The average WSS of the small vein is 0.62 Pa and 0.56 Pa, and the average WSS of the small artery is 2.99 Pa and 3.18 Pa, respectively. Similar to the behavior of the blood flow velocity and shear rate, the instantaneous WSS shows oscillation in both the small vein and the small artery: the peak WSS of the small vein is 0.45 and 0.49, and the peak WSS of the small artery is 1.66 Pa and 1.36 Pa, respectively.

[0045] In summary, the embodiments of the present application provide a method for measuring the shear parameters of a vessel wall, mainly including steps 701-703 as shown in Figure 7 .

[0046] Step 701, acquiring THG images of the equatorial plane of the blood vessel to be measured at two different positions in the blood flow direction.

[0047] In the embodiment of the present application, when measuring the wall shear parameter of the blood vessel, the THG images of two different positions on the equatorial plane of the blood vessel to be measured are needed to be obtained in the line scanning direction of the blood flow. The THG images include a first THG image corresponding to a first position and a second THG image corresponding to a second position. The first position is close to the wall of the blood vessel to be measured, the second position is between the first position and the center line of the equatorial plane, and the first position and the second position are both on the same perpendicular line of the center line.

[0048] Step 702, obtaining the first instantaneous blood flow velocity at the first position according to the first THG image, and obtaining the second instantaneous blood flow velocity at the second position according to the second THG image.

[0049] In the embodiment of the present application, after obtaining the first THG image and the second THG image, the first instantaneous blood flow velocity at the first position is obtained according to the first THG image, and the second instantaneous blood flow velocity at the second position is obtained according to the second THG image.

[0050] Step 703, calculating the instantaneous wall shear rate of the blood vessel to be measured according to the first instantaneous blood flow velocity and the second instantaneous blood flow velocity.

[0051] In the embodiment of the present application, after obtaining the first instantaneous blood flow velocity and the second instantaneous blood flow velocity, the instantaneous wall shear rate of the blood vessel to be measured is calculated according to the first instantaneous blood flow velocity and the second instantaneous blood flow velocity. It can be understood that the embodiment of the present application is mainly to calculate the instantaneous wall shear rate of the blood vessel to be measured according to the first instantaneous blood flow velocity and the second instantaneous blood flow velocity, and then calculate the instantaneous wall shear stress of the blood vessel to be measured according to the instantaneous wall shear rate. Specifically, the blood viscosity is calculated according to the instantaneous wall shear rate, so as to calculate the instantaneous wall shear stress of the blood vessel to be measured according to the instantaneous wall shear rate and the blood viscosity. The calculation formula and relationship involved are described above, and will not be repeated here.

[0052] The embodiment of the present application is realized based on three harmonic (THG) imaging, which is a common way of multi-photon microscopic imaging, has a sub-micron spatial resolution compared with ultrasonic imaging and phase contrast magnetic resonance imaging, and produces a nonlinear optical signal purely from an intrinsic origin, i.e., without the need of injecting exogenous fluorescent beads, and is a kind of label-free measurement scheme. Meanwhile, THG imaging also has an inherent three-dimensional slicing capability, and does not have a signal defocusing phenomenon, and can measure a transient value of a wall shear rate, and has higher measurement accuracy. The measurement of the wall shear rate by the embodiment of the present application only depends on its definition, i.e., the derivative of the flow rate to the distance, and is irrelevant to a flow model (such as Hagen-Poiseuille). Considering that the transient shear rate is measured by the technology of the embodiment of the present application, and the blood viscosity related to the shear rate can be measured at any specific shear rate, the transient WSS is irrelevant to the flow model. Although the embodiment of the present application uses a specific Quemada model for viscosity fitting, in the case that the Quemada model may fail, we can still measure the WSS according to the above procedure, because the blood viscosity related to the shear rate can be directly measured by the relationship between the two.

[0053] Referring to Figure 8 , Figure 8 A module block diagram of an electronic device provided by the embodiment of the present application is shown.

[0054] As Figure 8 shown, the embodiment of the present application further provides an electronic device 800, comprising a storage device 810 and at least one processor 820; wherein the storage device 810 is configured to store at least one program, and when the at least one program is executed by the at least one processor 820, the at least one processor 820 executes the measurement method of the wall shear parameter provided by the embodiment of the present application.

[0055] In some embodiments, the electronic device 800 can further comprise a bus 880, configured to connect the storage device 810 and the at least one processor 820 in communication.

[0056] Referring to Figure 9 , Figure 9 A module block diagram of a computer readable storage medium provided by the embodiment of the present application is shown.

[0057] As Figure 9 shown, the embodiment of the present application further provides a computer readable storage medium 900, and the computer readable storage medium 900 stores executable instructions 910, and the executable instructions 910 are executed to execute the measurement method of the wall shear parameter provided by the embodiment of the present application.

[0058] The steps of a method or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM, flash memory, ROM, electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. The storage medium can be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can reside in an ASIC.

[0059] In the foregoing disclosure, numerous specific details are set forth to provide a thorough understanding of the embodiments. However, implementations can be practiced without some or all of these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail.

[0060] It should be noted that each of the embodiments described herein can be implemented in a progressive manner, and each embodiment focuses on the differences from other embodiments. Therefore, the same or similar parts among the embodiments can be mutually referred to. For product-based embodiments, since they are similar to the method-based embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method-based embodiments.

[0061] It is also important to note that the use of relational terms such as first and second, and the like, are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, 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 can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0062] The above description of disclosed embodiments provides enabling concepts for making or using the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can 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

1. A method for measuring blood vessel wall shear parameters, characterized in that, include: THG images are obtained by linear scanning at two different locations on the equatorial plane of the blood vessel under test in the direction of blood flow. The THG images include a first THG image corresponding to a first location and a second THG image corresponding to a second location. The first location is close to the wall of the blood vessel under test, and the second location is located between the first location and the centerline of the equatorial plane. Both the first and second locations are on the same perpendicular line to the centerline, and the distance between the first and second locations is the diameter of a red blood cell. The linearly scanned THG images are obtained by synchronous linear scanning using a dual-wavelength femtosecond laser. The first instantaneous blood flow velocity at the first location is obtained from the first THG image, and the second instantaneous blood flow velocity at the second location is obtained from the second THG image; The instantaneous wall shear rate of the blood vessel under test is calculated based on the first instantaneous blood flow velocity and the second instantaneous blood flow velocity.

2. The method for measuring blood vessel wall shear parameters as described in claim 1, characterized in that, Before acquiring THG images of two different locations on the equatorial plane of the blood vessel to be tested, scanned linearly in the direction of blood flow, the method further includes: 3D stacked images of the blood vessels to be tested were obtained using THG imaging technology. Identify the upper and lower boundaries of the blood vessel to be tested from the 3D stacked imaging; The mid-plane between the upper boundary and the lower boundary is taken as the equatorial plane of the blood vessel to be tested.

3. The method for measuring blood vessel wall shear parameters as described in claim 1, characterized in that, The step of calculating the instantaneous wall shear rate of the blood vessel under test based on the first instantaneous blood flow velocity and the second instantaneous blood flow velocity includes: The instantaneous blood flow velocity and the second instantaneous blood flow velocity are substituted into the first calculation formula to calculate the instantaneous wall shear rate of the blood vessel under test; wherein, the first calculation formula is expressed as: γ=|(v2-v1) / (r2-r1)|; γ represents the instantaneous wall shear rate of the blood vessel under test, v2 represents the second instantaneous blood flow velocity, v1 represents the first instantaneous blood flow velocity, r2 represents the distance between the second position and the centerline, and r1 represents the distance between the first position and the centerline.

4. The method for measuring blood vessel wall shear parameters as described in claim 3, characterized in that, The distance between the first position and the second position is 5 μm.

5. The method for measuring blood vessel wall shear parameters as described in claim 3, characterized in that, After calculating the instantaneous wall shear rate of the blood vessel under test based on the first instantaneous blood flow velocity and the second instantaneous blood flow velocity, the method further includes: The instantaneous wall shear stress of the blood vessel under test is calculated based on the instantaneous wall shear rate.

6. The method for measuring blood vessel wall shear parameters as described in claim 5, characterized in that, The step of calculating the instantaneous wall shear stress of the blood vessel under test based on the instantaneous wall shear rate includes: The blood viscosity was calculated based on the instantaneous wall shear rate. The instantaneous wall shear stress of the blood vessel under test is calculated based on the instantaneous wall shear rate and the blood viscosity.

7. The method for measuring blood vessel wall shear parameters as described in claim 6, characterized in that, The calculation of blood viscosity based on the instantaneous wall shear rate includes: Blood viscosity is calculated based on the relationship between the instantaneous wall shear rate and blood viscosity; wherein, the relationship between the instantaneous wall shear rate and blood viscosity is expressed as follows: m=n p [1-0.5k Q Hct] -2 , ； η p Hct represents plasma viscosity, Hct represents hematocrit, k0 represents the maximum volume fraction when the wall shear rate is zero, and k ∞ This represents the maximum volume fraction at an infinite wall shear rate. The characteristic rate of red blood cell rosary formation / degradation is represented by μ, and the blood viscosity is represented by μ.

8. The method for measuring blood vessel wall shear parameters as described in claim 6, characterized in that, The calculation of the instantaneous wall shear stress of the blood vessel under test based on the instantaneous wall shear rate and the blood viscosity includes: The instantaneous wall shear rate and the blood viscosity are substituted into the second calculation formula to calculate the instantaneous wall shear stress of the blood vessel under test; wherein, the second calculation formula is expressed as: τ=μγ; τ represents the instantaneous wall shear stress of the blood vessel under test.

9. An electronic device, characterized in that, The method includes a storage device and at least one processor; the storage device is used to store at least one program, and when the at least one program is executed by the at least one processor, the at least one processor causes the at least one processor to perform the method as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores executable instructions that, when executed, perform the method as described in any one of claims 1-8.

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