Fractional flow reserve calculation method and device, electronic equipment and readable medium

Abstract

The invention relates to a fractional flow reserve calculation method and device, electronic equipment and a readable medium. The method comprises the following steps: constructing a three-dimensional geometric model of a target blood vessel; performing dimension reduction simulation on the three-dimensional geometric model to obtain first blood flow velocity distribution and first pressure distribution of the target blood vessel; the first blood flow velocity distribution and the first pressure distribution serve as initial conditions of three-dimensional simulation, iterative calculation is conducted on the three-dimensional geometric model, and target blood flow velocity distribution and target pressure distribution of the target blood vessel are obtained; and calculating the fractional flow reserve of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution. According to the scheme provided by the invention, the calculation efficiency can be greatly improved under the condition that the calculation precision is not influenced.

Description

Technical Field

[0001] The present application relates to the field of data processing technology, and in particular to a method, device, electronic device and readable medium for calculating blood flow reserve fraction. Background Art

[0002] FFR (Fractional Flow Reserve) is the gold standard for clinical evaluation of ischemic heart disease. FFR can be calculated by using a pressure microcatheter or pressure guidewire under maximum hyperemia conditions, using the pressure at the distal end of the coronary artery stenosis (Pd) and the pressure at the proximal end of the stenosis (aortic pressure Pa).

[0003] The FFR measured by a pressure microcatheter or pressure guidewire is an important hemodynamic indicator of coronary artery stenosis, but it has some limitations. For example, invasive diagnosis may cause certain harm to patients, or some patients may react unwell when adenosine is injected, and the pressure guidewire is too expensive.

[0004] In order to solve the above problems, the related art uses CFD (Computational Fluid Dynamics) to calculate FFR, which is non-invasive. However, CFD calculation of FFR requires a large number of grids and repeated iterations, which requires more computing resources and leads to a long calculation time, so the calculation efficiency is not high, or due to the compression of simulation variables and functions, part of the calculation accuracy is lost, so the calculation accuracy is not high. Summary of the invention

[0005] In order to solve or partially solve the problems existing in the related art, the present application provides a blood flow reserve fraction calculation method, device, electronic device and readable medium, which can greatly improve the calculation efficiency without affecting the calculation accuracy.

[0006] In a first aspect, the present application provides a method for calculating blood flow reserve fraction, the method comprising:

[0007] Constructing a three-dimensional geometric model of the target blood vessel;

[0008] Performing dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel;

[0009] Using the first blood flow velocity distribution and the first pressure distribution as initial conditions for three-dimensional simulation, performing iterative calculation on the three-dimensional geometric model to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel;

[0010] The blood flow reserve fraction of the target blood vessel is calculated according to the target blood flow velocity distribution and the target pressure distribution.

[0011] In one embodiment, the performing dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel includes:

[0012] Extracting a three-dimensional center line of the three-dimensional geometric model; wherein the three-dimensional center line includes a plurality of preset points;

[0013] Extract each cross section perpendicular to the three-dimensional center line at each preset point;

[0014] Calculating the average blood flow velocity of each cross section;

[0015] Writing the average blood flow velocity value of each cross section into the three-dimensional center line to obtain a first blood flow velocity distribution of the target blood vessel;

[0016] Calculating the pressure of each cross section;

[0017] The pressure values ​​of the respective cross sections are written into the three-dimensional center line to obtain a first pressure distribution of the target blood vessel.

[0018] In one embodiment, calculating the average blood flow velocity of each cross section includes:

[0019] Calculating the area of ​​each cross section;

[0020] Calculating the average cross-sectional area of ​​the target blood vessel according to the areas of the respective cross-sections;

[0021] determining an average blood flow velocity of the target blood vessel;

[0022] Calculating the blood flow rate of the target blood vessel according to the average blood flow velocity of the target blood vessel and the average cross-sectional area;

[0023] The average blood flow velocity of each cross section is calculated according to the blood vessel flow rate of the target blood vessel.

[0024] In one embodiment, the calculating the pressure of each cross section includes:

[0025] According to the diameter change of the target blood vessel, the target blood vessel is divided into a first blood vessel segment without stenosis characteristics and a second blood vessel segment with stenosis characteristics; wherein the second blood vessel segment includes a first sub-segment with a monotonically decreasing diameter and a second sub-segment with a monotonically increasing diameter;

[0026] calculating a pressure drop of the first vessel segment, and calculating a pressure drop of the first sub-segment, and calculating a pressure drop of the second sub-segment;

[0027] The pressure of each cross section is calculated according to the pressure drop of the first blood vessel segment, the pressure drop of the first sub-segment and the pressure drop of the second sub-segment.

[0028] In one embodiment, the first blood flow velocity distribution is used to characterize the distribution of the first blood flow velocity at each preset point, and the first pressure distribution is used to characterize the distribution of the first pressure at each preset point; the first blood flow velocity distribution and the first pressure distribution are used as initial conditions for three-dimensional simulation, and the three-dimensional geometric model is iteratively calculated to obtain the target blood flow velocity distribution and target pressure distribution of the target blood vessel, including:

[0029] Dividing the grid required for CFD calculation based on the three-dimensional geometric model to obtain a three-dimensional grid model of the target blood vessel;

[0030] Mapping the first blood flow velocity and the first pressure of each preset point to the three-dimensional grid model to obtain the second blood flow velocity and the second pressure represented by each grid node;

[0031] Determining the second blood flow velocity and the second pressure represented by each grid node as initial conditions for the three-dimensional simulation;

[0032] The three-dimensional grid model is iteratively calculated based on the initial conditions to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel.

[0033] In one embodiment, the target blood flow velocity distribution is used to characterize the distribution of the target blood flow velocity at each preset point, and the target pressure distribution is used to characterize the distribution of the target pressure at each preset point; and calculating the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution includes:

[0034] Obtain aortic pressure;

[0035] The blood flow reserve fraction of the target blood vessel is calculated according to the aortic pressure and the target blood flow velocity and target pressure at each preset point.

[0036] In one embodiment, constructing a three-dimensional geometric model of a target blood vessel comprises:

[0037] acquiring multiple angiographic images of the target blood vessel;

[0038] The target blood vessel is three-dimensionally reconstructed using the multiple angiography images to obtain a three-dimensional geometric model of the target blood vessel.

[0039] A second aspect of the present application provides a blood flow reserve fraction calculation device, the device comprising:

[0040] A three-dimensional construction module, used to construct a three-dimensional geometric model of the target blood vessel;

[0041] A dimensionality reduction simulation module, used for performing dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel;

[0042] a three-dimensional simulation module, configured to use the first blood flow velocity distribution and the first pressure distribution as initial conditions for three-dimensional simulation, perform iterative calculations on the three-dimensional geometric model, and obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel;

[0043] The blood flow reserve fraction calculation module is used to calculate the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution.

[0044] A third aspect of the present application provides an electronic device, including:

[0045] Processor; and

[0046] The memory stores executable codes thereon, and when the executable codes are executed by the processor, the processor is caused to execute the method as described above.

[0047] A fourth aspect of the present application provides a computer-readable storage medium having executable code stored thereon. When the executable code is executed by a processor of an electronic device, the processor is caused to execute the method as described above.

[0048] The technical solution provided by this application may have the following beneficial effects:

[0049] The solution provided by the present application constructs a three-dimensional geometric model of a target blood vessel; performs dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel; uses the first blood flow velocity distribution and the first pressure distribution as initial conditions for the three-dimensional simulation, performs iterative calculations on the three-dimensional geometric model to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel; and calculates the blood flow reserve fraction of the target blood vessel based on the target blood flow velocity distribution and the target pressure distribution. The present application combines dimensionality reduction simulation with three-dimensional simulation to perform CFD calculation of FFR, and uses the calculation results of dimensionality reduction simulation as initial conditions for three-dimensional simulation, thereby greatly improving the calculation efficiency without affecting the calculation accuracy.

[0050] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The above and other objects, features and advantages of the present application will become more apparent by describing in more detail the exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0052] Figure 1 is a flow chart of a method for calculating blood flow reserve fraction shown in an embodiment of the present application;

[0053] Figure 2 is another flow chart of the method for calculating the blood flow reserve fraction shown in the embodiment of the present application;

[0054] Figure 3 is a flow chart of blood flow reserve fraction calculation shown in an embodiment of the present application;

[0055] Figure 4 is a schematic diagram of the structure of a blood flow reserve fraction calculation device shown in an embodiment of the present application;

[0056] Figure 5 It is a schematic diagram of the structure of an electronic device shown in an embodiment of the present application. DETAILED DESCRIPTION

[0057] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0058] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0059] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0060] Conventional cardiovascular imaging techniques such as coronary X-ray angiography, coronary CT angiography, and intracavitary imaging techniques can image the anatomy of the coronary arteries and show the site and extent of vascular damage, but they have certain limitations in determining whether the damage causes ischemia and locating the culprit blood vessels.

[0061] FFR can make up for the shortcomings of the above imaging techniques, optimize the diagnosis of ischemic heart disease and the selection of culprit blood vessels, reduce unnecessary stent implantation, and improve the long-term treatment efficacy of patients. It has become the gold standard for clinical evaluation of ischemic heart disease. FFR can be obtained by dividing the maximum myocardial blood flow in the presence of epicardial coronary artery stenosis by the maximum blood flow when the blood vessels are normal. Under maximum hyperemia, the blood flow ratio can be replaced by the pressure value. Therefore, a pressure microcatheter or pressure guidewire can be used. Under maximum hyperemia, FFR can be calculated by the pressure at the distal end of the coronary stenosis (Pd) and the pressure at the proximal end of the stenosis (aortic pressure Pa).

[0062] The FFR measured by a pressure microcatheter or pressure guidewire is an important hemodynamic indicator of coronary artery stenosis, but it has some limitations. For example, invasive diagnosis may cause certain harm to patients, or the use of adenosine, a drug that induces maximum hyperemia response, is required during the FFR test. However, some patients experience discomfort when adenosine is injected, and the pressure guidewire is too expensive.

[0063] With the development of science and technology and research level, especially in the fields of medical imaging and reconstruction technology, high-performance computing, etc., the application of CFD to calculate FFR is becoming a rapidly developing frontier direction. However, the application of CFD to calculate FFR in related technologies requires a large number of grids and repeated iterations, which requires more computing resources and leads to a long calculation time. Therefore, the calculation efficiency is not high, or due to the compression of simulation variables and functions, part of the calculation accuracy is lost, so the calculation accuracy is not high.

[0064] In response to the above problems, an embodiment of the present application provides a method for calculating the blood flow reserve fraction. The present application performs CFD calculation of FFR by combining dimensionality reduction simulation with three-dimensional simulation, and uses the calculation results of the dimensionality reduction simulation as the initial conditions of the three-dimensional simulation, thereby greatly improving the calculation efficiency without affecting the calculation accuracy.

[0065] The technical solution of the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0066] Figure 1 It is a flow chart of a method for calculating blood flow reserve fraction shown in an embodiment of the present application.

[0067] See also Figure 1 , the blood flow reserve fraction calculation method of the present application comprises:

[0068] S110, constructing a three-dimensional geometric model of the target blood vessel.

[0069] In the embodiment of the present application, a three-dimensional geometric model of the target blood vessel can be constructed first, so as to facilitate the subsequent CFD simulation based on the three-dimensional geometric model. The target blood vessel can be a culprit blood vessel covering myocardial ischemia and myocardial infarction. The target blood vessel can include a trunk and branches. The embodiment of the present application can only perform three-dimensional reconstruction on the trunk of the target blood vessel, thereby obtaining a three-dimensional geometric model of the trunk of the target blood vessel.

[0070] It should be noted that CFD is the abbreviation of Computational Fluid Dynamics, which has developed along with the development of computer technology and numerical computing technology. Simply put, CFD is equivalent to "virtually" doing experiments on computers to simulate actual fluid flow conditions. Therefore, CFD numerically solves the differential equations that control fluid flow to obtain the discrete distribution of the flow field of fluid flow in a continuous area, thereby approximately simulating the fluid flow condition.

[0071] S111, performing dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel.

[0072] After constructing the three-dimensional geometric model of the target blood vessel, the embodiment of the present application can perform dimensionality reduction simulation on the three-dimensional geometric model, so as to obtain the first blood flow velocity distribution and the first pressure distribution of the target blood vessel by dimensionality reduction calculation.

[0073] Among them, dimensionality reduction simulation belongs to CFD simulation. Dimensionality reduction refers to converting high-dimensional data into low-dimensional data, which can reduce the complexity and cost of calculations and save computing resources and time. In CFD dimensionality reduction simulation, by analyzing the main variables and factors in fluid motion, multiple complex variables and functions are compressed into a small number of representative variables, so that calculations can be performed more quickly to obtain results.

[0074] S112, using the first blood flow velocity distribution and the first pressure distribution as initial conditions for the three-dimensional simulation, performing iterative calculations on the three-dimensional geometric model to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel.

[0075] Since dimensionality reduction simulation compresses simulation variables and functions, the simulation speed of dimensionality reduction simulation is faster, but dimensionality reduction simulation will lose some calculation accuracy.

[0076] In order to greatly improve the calculation efficiency without affecting the calculation accuracy, the embodiment of the present application can use the calculation results of the dimensionality reduction simulation as the initial conditions of the three-dimensional simulation, that is, the first blood flow velocity distribution and the first pressure distribution can be used as the initial conditions of the three-dimensional simulation, and the three-dimensional geometric model can be iteratively calculated, so as to obtain the target blood flow velocity distribution and target pressure distribution of the target blood vessel, and the target blood flow velocity distribution and target pressure distribution are the calculation results of the three-dimensional simulation.

[0077] Among them, three-dimensional simulation belongs to CFD simulation, and three-dimensional simulation is theoretically more accurate. Since the embodiment of the present application uses the calculation results of dimensionality reduction simulation as the initial conditions of three-dimensional simulation, the number of iterations of three-dimensional simulation can be greatly reduced, thereby solving the problem of slow calculation speed of three-dimensional simulation and improving the calculation efficiency of three-dimensional simulation.

[0078] S113, calculating the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution.

[0079] After obtaining the target blood flow velocity distribution and target pressure distribution of the target blood vessel, the embodiment of the present application can calculate the blood flow reserve fraction (FFR) of the target blood vessel based on the target blood flow velocity distribution and target pressure distribution in combination with the aortic pressure (Pa).

[0080] Compared with traditional FFR, the application of CFD to calculate FFR in the embodiment of the present application is minimally invasive. According to clinical trial comparisons, CFD calculation of FFR has a very high ability to diagnose myocardial ischemia in terms of accuracy, sensitivity, and specificity at the level of each vascular level of individual patients, and is more superior to methods evaluated by imaging.

[0081] In addition, the embodiment of the present application solves the problem of slow three-dimensional simulation calculation speed by combining the dimensionality reduction simulation method without affecting the calculation accuracy, thereby improving the calculation efficiency of the three-dimensional simulation.

[0082] As can be seen from this example, the solution provided by this application constructs a three-dimensional geometric model of the target blood vessel; performs dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel; uses the first blood flow velocity distribution and the first pressure distribution as initial conditions for the three-dimensional simulation, performs iterative calculations on the three-dimensional geometric model, and obtains a target blood flow velocity distribution and a target pressure distribution of the target blood vessel; calculates the blood flow reserve fraction of the target blood vessel based on the target blood flow velocity distribution and the target pressure distribution. This application combines dimensionality reduction simulation with three-dimensional simulation to perform CFD calculation of FFR, and uses the calculation results of dimensionality reduction simulation as initial conditions for three-dimensional simulation, thereby greatly improving the calculation efficiency without affecting the calculation accuracy.

[0083] Figure 2is another flow chart of the blood flow reserve fraction calculation method shown in an embodiment of the present application.

[0084] See also Figure 2 , the blood flow reserve fraction calculation method of the present application comprises:

[0085] S210, constructing a three-dimensional geometric model of the target blood vessel.

[0086] In the embodiment of the present application, a three-dimensional geometric model of the target blood vessel can be constructed first, so as to facilitate the subsequent CFD simulation based on the three-dimensional geometric model. The target blood vessel can be a culprit blood vessel covering myocardial ischemia and myocardial infarction. The target blood vessel can include a trunk and branches. The embodiment of the present application can only perform three-dimensional reconstruction on the trunk of the target blood vessel, thereby obtaining a three-dimensional geometric model of the trunk of the target blood vessel.

[0087] In one embodiment, constructing a three-dimensional geometric model of a target blood vessel may include:

[0088] Acquire multiple angiographic images of the target blood vessel; use the multiple angiographic images to perform three-dimensional reconstruction of the target blood vessel to obtain a three-dimensional geometric model of the target blood vessel.

[0089] In practical applications, contrast medium angiography can be performed on the patient's target blood vessels, and multiple angiographic images of the target blood vessels can be obtained by using a DSA (Digital Subtraction Angiography) device, wherein the angiographic image can be a projection image of the target blood vessels, that is, the angiographic image can be a two-dimensional image.

[0090] The embodiment of the present application can respectively extract the two-dimensional trunk centerline and the two-dimensional trunk contour line of the target blood vessel from multiple angiography images, use the two-dimensional trunk centerline of the target blood vessel in the multiple angiography images to perform spatial coordinate transformation, construct the three-dimensional trunk centerline of the target blood vessel, and then use the two-dimensional trunk contour line and the three-dimensional trunk centerline of the target blood vessel to perform three-dimensional reconstruction, so as to obtain a three-dimensional geometric model of the trunk of the target blood vessel, so as to subsequently use CFD to perform numerical simulation on the three-dimensional geometric model of the reconstructed trunk of the target blood vessel, so as to more accurately calculate the FFR of the trunk of the target blood vessel, and then perform a more accurate functional evaluation of the target blood vessel.

[0091] In addition, the embodiment of the present application can also construct a complete vascular tree model of the target blood vessel, that is, a three-dimensional geometric model of the trunk and branches of the target blood vessel can be constructed, so that CFD simulation can be performed on the vascular tree model of the target blood vessel later. The embodiment of the present application does not limit this.

[0092] S211, extracting the three-dimensional center line of the three-dimensional geometric model; wherein the three-dimensional center line includes a plurality of preset points.

[0093] After the three-dimensional geometric model of the target blood vessel is constructed, a three-dimensional centerline can be extracted from the three-dimensional geometric model, and the three-dimensional centerline can refer to the three-dimensional trunk centerline. In the embodiment of the present application, multiple points can be selected from the three-dimensional trunk centerline as preset points, so as to subsequently calculate the velocity and pressure for each preset point.

[0094] S212, extracting each cross section of each preset point that is perpendicular to the three-dimensional center line.

[0095] In the embodiment of the present application, multiple cross sections can be obtained by extracting the cross sections perpendicular to the three-dimensional center line where each preset point is located. For example, assuming there are n preset points, the cross sections perpendicular to the three-dimensional center line where each preset point is located are extracted to obtain n cross sections, and each preset point can correspond to one cross section. Where n is a positive integer.

[0096] S213, calculating the average blood flow velocity of each cross section.

[0097] After the contrast agent is injected into the target blood vessel, as the contrast agent flows along the target blood vessel, the outline of the entire target blood vessel will slowly emerge. The embodiment of the present application can calculate the average blood flow velocity of each cross section during this process.

[0098] In one embodiment, calculating the average blood flow velocity of each cross section may include:

[0099] Calculate the area of ​​each cross section; calculate the average cross-sectional area of ​​the target blood vessel based on the area of ​​each cross section; determine the average blood flow velocity of the target blood vessel; calculate the vascular flow rate of the target blood vessel based on the average blood flow velocity and the average cross-sectional area of ​​the target blood vessel; calculate the average blood flow velocity of each cross section based on the vascular flow rate of the target blood vessel.

[0100] In a specific implementation, the diameter of each cross section can be obtained, and based on the diameter of each cross section, the area of ​​each cross section can be calculated, so that the areas of n cross sections can be obtained. For the convenience of description, the areas of n cross sections can be recorded as A0, A1, ..., A n Then, the average area of ​​the n cross sections can be calculated to obtain the average cross-sectional area A of the target blood vessel.

[0101] After the contrast agent is injected into the target blood vessel, as the contrast agent flows along the target blood vessel, the outline of the entire target blood vessel will slowly appear, so the length of the target blood vessel in the multiple angiography images taken by the DSA device changes frame by frame. Therefore, the embodiment of the present application can calculate the average blood flow velocity v of the contrast agent passing through the target blood vessel based on multiple angiography images using the TIMI (Thrombolysis In Myocardial Infarction, which is used to describe the coronary blood flow after intracoronary thrombolysis in acute myocardial infarction) Frame Count algorithm.

[0102] After obtaining the average blood flow velocity v and the average cross-sectional area A of the target blood vessel, the average blood flow velocity v and the average cross-sectional area A can be substituted into Formula 1 to calculate the vascular flow rate Q of the target blood vessel:

[0103] Q=A*v Formula 1

[0104] The blood vessel flow rate Q may refer to the blood vessel flow rate of the trunk of the target blood vessel.

[0105] In the embodiment of the present application, the blood vessel flow rate Q of the target blood vessel can be calculated and the area A0, A1, ..., A of each cross section can be calculated. n The ratio of each ratio is the average blood flow velocity of each cross section. For the convenience of description, the average blood flow velocity of n cross sections can be recorded as v0, v1, ..., v n .

[0106] S214, writing the value of the average blood flow velocity of each cross section into the three-dimensional center line to obtain a first blood flow velocity distribution of the target blood vessel.

[0107] Calculate the average blood flow velocity v0, v1, ..., v in each section n Then, the embodiment of the present application can calculate the average blood flow velocity v0, v1, ..., v of each cross section. n Specifically, since the preset points and the cross sections have a one-to-one correspondence, the average blood flow velocity v0, v1, ..., v of each cross section can be written into the three-dimensional center line based on the position of each preset point on the three-dimensional center line. n The values ​​of are written into the corresponding positions on the three-dimensional center line respectively, so that the first blood flow velocity distribution of the target blood vessel can be obtained.

[0108] S215, calculating the pressure of each cross section.

[0109] The target blood vessel is narrowed, so the pressure at different locations of the target blood vessel may not be the same. The embodiment of the present application can first reasonably segment the target blood vessel based on the presence or absence of obvious narrowing characteristics, and then calculate the pressure of each cross section for each segment of the target blood vessel.

[0110] In one embodiment, calculating the pressure of each cross section may include:

[0111] According to the diameter change of the target blood vessel, the target blood vessel is divided into a first blood vessel segment without stenosis characteristics and a second blood vessel segment with stenosis characteristics; wherein the second blood vessel segment includes a first sub-segment with a monotonically decreasing diameter and a second sub-segment with a monotonically increasing diameter; the pressure drop of the first blood vessel segment is calculated, and the pressure drop of the first sub-segment is calculated, and the pressure drop of the second sub-segment is calculated; according to the pressure drop of the first blood vessel segment, the pressure drop of the first sub-segment and the pressure drop of the second sub-segment, the pressure of each cross section is calculated.

[0112] Specifically, the presence or absence of obvious stenosis characteristics can be determined based on the diameter change of the target blood vessel, so as to divide the target blood vessel into a first blood vessel segment without stenosis characteristics and a second blood vessel segment with stenosis characteristics. In other words, the first blood vessel segment can refer to the target blood vessel segment without obvious stenosis, and the second blood vessel segment can refer to the target blood vessel segment with obvious stenosis.

[0113] For the second blood vessel segment with stenosis characteristics, the pressure loss caused by the change in blood vessel diameter needs to be considered, so the diameter change of the second blood vessel segment can be further determined, and the second blood vessel segment can be divided into a first sub-segment with a monotonically decreasing diameter and a second sub-segment with a monotonically increasing diameter. In other words, the first sub-segment can refer to the portion of the second blood vessel segment where the blood vessel diameter gradually decreases, and the second sub-segment can refer to the portion of the second blood vessel segment where the blood vessel diameter gradually increases.

[0114] For the first blood vessel segment without stenosis characteristics, the pressure drop of the first blood vessel segment can be calculated according to the Poiseuille flow based on the average diameter of the first blood vessel segment:

[0115]

[0116] Wherein, μ is the viscosity coefficient, l is the segment length, V is the average blood flow velocity, and d is the average diameter. It should be noted that μ, l, V, and d in Formula 2 are all parameters of the first blood vessel segment.

[0117] For the first subsegment with a monotonically decreasing diameter, the main cause of the pressure drop is viscous losses:

[0118]

[0119] in,

[0120] Where μ is the viscosity coefficient, D0 is the diameter at the inlet, V0 is the average blood flow velocity at the inlet, K v is the integral of the diameter-related parameters along the three-dimensional centerline direction, A is the cross-sectional area of ​​the cross section where each preset point on the three-dimensional centerline is located, and D' is the cross-sectional diameter of the cross section where each preset point on the three-dimensional centerline is located. It should be noted that μ, D0, V0, K in Formula 3 and Formula 4 v , A and D' are all parameters of the first sub-segment.

[0121] For the second sub-segment with a monotonically increasing diameter, the main cause of the pressure drop is the expansion loss:

[0122]

[0123] Among them, A0 is the area at the entrance, A s is the stenosis area, ρ is the density, V0 is the average blood flow velocity at the entrance, K e is the expansion loss coefficient, which is generally 1 to 2. It should be noted that A0 and A in Formula 5 s , ρ, V0 and K e are all parameters of the second sub-segment.

[0124] The pressure drop △P of the first blood vessel segment is obtained 沿 , the pressure drop P of the first sub-segment v and the pressure drop P of the second sub-segment e After that, the pressure drop △P of the first blood vessel segment can be 沿 The pressure drop curve of the first blood vessel segment can be fitted based on the pressure drop P of the first sub-segment. v and the pressure drop P of the second sub-segment e The pressure drop curve of the second blood vessel segment is fitted. Then, by integrating the pressure drop curve of the first blood vessel segment with the pressure drop curve of the second blood vessel segment, the pressure drop curve of the target blood vessel can be obtained, and the pressure of each section can be obtained from the pressure drop curve of the target blood vessel. For the convenience of description, the pressures of n sections can be recorded as p0, p1, ..., p n .

[0125] S216, writing the pressure values ​​of each cross section into the three-dimensional center line to obtain a first pressure distribution of the target blood vessel.

[0126] Calculate the pressure of each section p0, p1, ..., p n After that, the embodiment of the present application can make each cross-sectional pressure p0, p1, ..., p nSpecifically, since the preset points and the cross sections have a one-to-one correspondence, the pressures p0, p1, ..., p of each cross section can be written into the three-dimensional center line based on the position of each preset point on the three-dimensional center line. n The values ​​of are written into the corresponding positions on the three-dimensional center line respectively, so that the first pressure distribution of the target blood vessel can be obtained.

[0127] S217, using the first blood flow velocity distribution and the first pressure distribution as initial conditions for the three-dimensional simulation, performing iterative calculations on the three-dimensional geometric model to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel.

[0128] Since dimensionality reduction simulation compresses simulation variables and functions, the simulation speed of dimensionality reduction simulation is faster, but dimensionality reduction simulation will lose some calculation accuracy.

[0129] In order to greatly improve the calculation efficiency without affecting the calculation accuracy, the embodiment of the present application can use the calculation results of the dimensionality reduction simulation as the initial conditions of the three-dimensional simulation, that is, the first blood flow velocity distribution and the first pressure distribution can be used as the initial conditions of the three-dimensional simulation, and the three-dimensional geometric model can be iteratively calculated, so as to obtain the target blood flow velocity distribution and target pressure distribution of the target blood vessel, and the target blood flow velocity distribution and target pressure distribution are the calculation results of the three-dimensional simulation.

[0130] Three-dimensional simulation is theoretically more accurate. Since the embodiment of the present application uses the calculation results of the dimensionality reduction simulation as the initial conditions of the three-dimensional simulation, the number of iterations of the three-dimensional simulation can be greatly reduced, thereby solving the problem of slow calculation speed of the three-dimensional simulation and improving the calculation efficiency of the three-dimensional simulation.

[0131] In one embodiment, the first blood flow velocity distribution is used to characterize the distribution of the first blood flow velocity at each preset point, and the first pressure distribution is used to characterize the distribution of the first pressure at each preset point; using the first blood flow velocity distribution and the first pressure distribution as initial conditions for the three-dimensional simulation, iteratively calculating the three-dimensional geometric model, and obtaining the target blood flow velocity distribution and target pressure distribution of the target blood vessel may include:

[0132] The grid required for CFD calculation is divided based on the three-dimensional geometric model to obtain a three-dimensional grid model of the target blood vessel; the first blood flow velocity and the first pressure of each preset point are mapped to the three-dimensional grid model to obtain the second blood flow velocity and the second pressure represented by each grid node; the second blood flow velocity and the second pressure represented by each grid node are determined as initial conditions of the three-dimensional simulation; the three-dimensional grid model is iteratively calculated based on the initial conditions to obtain the target blood flow velocity distribution and the target pressure distribution of the target blood vessel.

[0133] Three-dimensional simulation requires meshing of the three-dimensional geometric model, so the embodiment of the present application can divide the mesh required for CFD calculation based on the three-dimensional geometric model, so as to obtain a three-dimensional mesh model of the target blood vessel.

[0134] The first blood flow velocity distribution can reflect the distribution of the first blood flow velocity of each preset point on the three-dimensional center line, that is, v0, v1, ..., v n The first pressure distribution can reflect the distribution of the first pressure of each preset point on the three-dimensional center line, that is, p0, p1, ..., p n Distribution on the 3D centerline.

[0135] Since the first blood flow velocity and the first pressure are both stored on the three-dimensional center line, it is necessary to expand the preset points on the three-dimensional center line to the entire cross section, so as to map the first blood flow velocity and the first pressure of each preset point on the three-dimensional center line to the three-dimensional grid model. Specifically, the pressure of all points on the same cross section can be the same. Based on this, the first pressure of each preset point on the three-dimensional center line can be mapped to the three-dimensional grid model, so as to obtain the second pressure represented by each grid node. The velocity of all points on the same cross section can follow a parabolic distribution, where parabolic is a function used to solve parabolic partial differential equations. Based on this, the first blood flow velocity of each preset point on the three-dimensional center line can be mapped to the three-dimensional grid model, so as to obtain the second blood flow velocity represented by each grid node.

[0136] In an embodiment of the present application, the second blood flow velocity and the second pressure represented by each grid node can be determined as the initial conditions of the three-dimensional simulation. The initial conditions can refer to the initial boundary conditions. The initial boundary conditions can be applied to the three-dimensional grid model for iterative solution to obtain the target blood flow velocity distribution and target pressure distribution of the target blood vessel.

[0137] In the related art, the initial condition of CFD simulation is zero, which is equivalent to the CFD fluid flowing from a static state to a fully developed state. This process takes a long time to calculate, resulting in low calculation efficiency. The embodiment of the present application uses the calculation results of the dimensionality reduction simulation as the initial condition of the three-dimensional simulation, which is equivalent to the CFD fluid flowing from a half-developed state to a fully developed state, thereby greatly reducing the number of iterations of the three-dimensional simulation and greatly reducing the calculation time, thereby solving the problem of slow calculation speed of the three-dimensional simulation and improving the calculation efficiency of the three-dimensional simulation.

[0138] S218, calculating the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution.

[0139] After obtaining the target blood flow velocity distribution and target pressure distribution of the target blood vessel, the embodiment of the present application can calculate the blood flow reserve fraction (FFR) of the target blood vessel based on the target blood flow velocity distribution and target pressure distribution in combination with the aortic pressure (Pa).

[0140] Compared with traditional FFR, the CFD calculation of FFR in the embodiment of the present application is minimally invasive, and has very high capabilities in diagnosing myocardial ischemia in terms of accuracy, sensitivity, and specificity at the scale of each vascular level of individual patients, and is more superior than methods evaluated through imaging.

[0141] In addition, the embodiment of the present application solves the problem of slow three-dimensional simulation calculation speed by combining the dimensionality reduction simulation method without affecting the calculation accuracy, thereby improving the calculation efficiency of the three-dimensional simulation.

[0142] In one embodiment, the target blood flow velocity distribution is used to characterize the distribution of the target blood flow velocity at each preset point, and the target pressure distribution is used to characterize the distribution of the target pressure at each preset point; and calculating the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution may include:

[0143] The aortic pressure is obtained; and the blood flow reserve fraction of the target blood vessel is calculated based on the aortic pressure and the target blood flow velocity and target pressure at each preset point.

[0144] In the embodiment of the present application, the aortic pressure (Pa) can be detected based on the hemodynamic pressure sensor. Among them, the target blood flow velocity distribution can reflect the distribution of the target blood flow velocity of each preset point on the three-dimensional center line, and the target pressure distribution can reflect the distribution of the target pressure of each preset point on the three-dimensional center line. Therefore, the blood flow reserve fraction (FFR) of each preset point on the target blood vessel can be calculated based on the target blood flow velocity and target pressure of each preset point, combined with the aortic pressure (Pa), and the blood flow reserve fraction (FFR) of each point on the target blood vessel can be obtained based on the blood flow reserve fraction (FFR) of each preset point.

[0145] As can be seen from this example, the solution provided by the present application is to construct a three-dimensional geometric model of the target blood vessel; extract the three-dimensional centerline of the three-dimensional geometric model; wherein the three-dimensional centerline includes multiple preset points; extract each section perpendicular to the three-dimensional centerline of each preset point; calculate the average blood flow velocity of each section; write the value of the average blood flow velocity of each section into the three-dimensional centerline to obtain the first blood flow velocity distribution of the target blood vessel; calculate the pressure of each section; write the value of the pressure of each section into the three-dimensional centerline to obtain the first pressure distribution of the target blood vessel; use the first blood flow velocity distribution and the first pressure distribution as the initial conditions of the three-dimensional simulation, iteratively calculate the three-dimensional geometric model, and obtain the target blood flow velocity distribution and target pressure distribution of the target blood vessel; calculate the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution. The present application combines dimensionality reduction simulation with three-dimensional simulation to perform CFD calculation of FFR, and uses the calculation results of dimensionality reduction simulation as the initial conditions of three-dimensional simulation, thereby greatly improving the calculation efficiency without affecting the calculation accuracy.

[0146] Figure 3 This is a flow chart for calculating the blood flow reserve fraction. In order to enable those skilled in the art to better understand the embodiments of the present application, the embodiments of the present application are explained below through the following examples.

[0147] S301, constructing a three-dimensional geometric model of the target blood vessel based on a plurality of angiography images of the target blood vessel.

[0148] S302: Extract the three-dimensional center line of the target blood vessel based on the three-dimensional geometric model.

[0149] S303, calculate the area A0, A1, ..., A of each cross section perpendicular to the three-dimensional center line n , based on the area of ​​each cross section A0, A1, ..., A n , calculate the average cross-sectional area A of the target blood vessel.

[0150] S304, calculating the blood vessel flow rate Q of the target blood vessel based on the average blood flow velocity v and the average cross-sectional area A of the target blood vessel.

[0151] S305a, dividing the target blood vessel into a first blood vessel segment without stenosis characteristics and a second blood vessel segment with stenosis characteristics; wherein the second blood vessel segment includes a first sub-segment with a monotonically decreasing diameter and a second sub-segment with a monotonically increasing diameter; based on the pressure drop of the first blood vessel segment, the pressure drop of the first sub-segment and the pressure drop of the second sub-segment, calculating the first pressure distribution of the target blood vessel by dimensionality reduction.

[0152] S305b, based on the blood vessel flow rate Q of the target blood vessel, calculate a first blood flow velocity distribution of the target blood vessel by dimensionality reduction.

[0153] S306a, dividing the grid required for CFD calculation based on the three-dimensional geometric model to obtain a three-dimensional grid model of the target blood vessel.

[0154] S306b, mapping the first blood flow velocity distribution and the first pressure distribution into the three-dimensional grid model to obtain initial conditions for the three-dimensional simulation; wherein the initial conditions are the second blood flow velocity and the second pressure represented by each grid node.

[0155] S307, performing iterative calculation of three-dimensional simulation on the three-dimensional grid model based on the initial conditions to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel.

[0156] S308, based on the target blood flow velocity distribution and the target pressure distribution, combined with the aortic pressure (Pa), the blood flow reserve fraction (FFR) of the target blood vessel is calculated.

[0157] Corresponding to the aforementioned application function implementation method embodiment, the present application also provides a blood flow reserve fraction calculation device, an electronic device, a computer-readable storage medium and corresponding embodiments.

[0158] Figure 4 It is a schematic diagram of the structure of a blood flow reserve fraction calculation device shown in an embodiment of the present application.

[0159] See also Figure 4 The present application provides a blood flow reserve fraction calculation device, which may include:

[0160] A three-dimensional construction module 401 is used to construct a three-dimensional geometric model of a target blood vessel;

[0161] A dimensionality reduction simulation module 402 is used to perform dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel;

[0162] The three-dimensional simulation module 403 is used to use the first blood flow velocity distribution and the first pressure distribution as initial conditions for the three-dimensional simulation, perform iterative calculations on the three-dimensional geometric model, and obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel;

[0163] The blood flow reserve fraction calculation module 404 is used to calculate the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution.

[0164] In one embodiment, the dimension reduction simulation module 402 may include:

[0165] A 3D centerline extraction submodule is used to extract a 3D centerline of a 3D geometric model; wherein the 3D centerline includes a plurality of preset points;

[0166] A cross-section extraction submodule, used to extract each cross-section of each preset point perpendicular to the three-dimensional center line;

[0167] The cross-sectional flow velocity calculation submodule is used to calculate the average blood flow velocity of each cross section;

[0168] A first writing submodule is used to write the value of the average blood flow velocity of each cross section into the three-dimensional center line to obtain a first blood flow velocity distribution of the target blood vessel;

[0169] Section pressure calculation submodule, used to calculate the pressure of each section;

[0170] The second writing submodule is used to write the pressure values ​​of each cross section into the three-dimensional center line to obtain a first pressure distribution of the target blood vessel.

[0171] In one embodiment, the cross-sectional flow velocity calculation submodule may include:

[0172] A cross-sectional area calculation unit is used to calculate the area of ​​each cross section;

[0173] an average cross-sectional area calculation unit, used to calculate the average cross-sectional area of ​​the target blood vessel according to the areas of each cross section;

[0174] a blood vessel flow velocity determination unit, used to determine an average blood flow velocity of a target blood vessel;

[0175] a blood vessel flow calculation unit, used to calculate the blood vessel flow of the target blood vessel according to the average blood flow velocity and the average cross-sectional area of ​​the target blood vessel;

[0176] The cross-sectional flow velocity unit is used to calculate the average blood flow velocity of each cross section according to the blood vessel flow of the target blood vessel.

[0177] In one embodiment, the cross-sectional pressure calculation submodule may include:

[0178] A segmentation unit is used to divide the target blood vessel into a first blood vessel segment without stenosis characteristics and a second blood vessel segment with stenosis characteristics according to the diameter change of the target blood vessel; wherein the second blood vessel segment includes a first sub-segment with a monotonically decreasing diameter and a second sub-segment with a monotonically increasing diameter;

[0179] a pressure drop calculation unit, configured to calculate the pressure drop of the first blood vessel segment, the pressure drop of the first sub-segment, and the pressure drop of the second sub-segment;

[0180] The cross-sectional pressure calculation unit is used to calculate the pressure of each cross-section according to the pressure drop of the first blood vessel segment, the pressure drop of the first sub-segment and the pressure drop of the second sub-segment.

[0181] In one embodiment, the first blood flow velocity distribution is used to characterize the distribution of the first blood flow velocity at each preset point, and the first pressure distribution is used to characterize the distribution of the first pressure at each preset point; the three-dimensional simulation module 403 may include:

[0182] A meshing submodule is used to divide the mesh required for CFD calculation based on the three-dimensional geometric model to obtain a three-dimensional mesh model of the target blood vessel;

[0183] A mapping submodule, used for mapping the first blood flow velocity and the first pressure of each preset point into the three-dimensional grid model to obtain the second blood flow velocity and the second pressure represented by each grid node;

[0184] An initial condition determination submodule, used to determine the second blood flow velocity and the second pressure represented by each grid node as initial conditions for three-dimensional simulation;

[0185] The iterative calculation submodule is used to perform iterative calculation on the three-dimensional grid model based on the initial conditions to obtain the target blood flow velocity distribution and target pressure distribution of the target blood vessel.

[0186] In one embodiment, the target blood flow velocity distribution is used to characterize the distribution of the target blood flow velocity at each preset point, and the target pressure distribution is used to characterize the distribution of the target pressure at each preset point; the blood flow reserve fraction calculation module 404 may include:

[0187] An aortic pressure acquisition submodule, used for acquiring aortic pressure;

[0188] The blood flow reserve fraction calculation submodule is used to calculate the blood flow reserve fraction of the target blood vessel based on the aortic pressure and the target blood flow velocity and target pressure at each preset point.

[0189] In one embodiment, the three-dimensional construction module 401 may include:

[0190] Angiographic image acquisition submodule, used for acquiring multiple angiographic images of target blood vessels;

[0191] The three-dimensional reconstruction submodule is used to perform three-dimensional reconstruction of the target blood vessel using multiple angiography images to obtain a three-dimensional geometric model of the target blood vessel.

[0192] As can be seen from this example, the solution provided by this application constructs a three-dimensional geometric model of the target blood vessel; performs dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel; uses the first blood flow velocity distribution and the first pressure distribution as initial conditions for the three-dimensional simulation, performs iterative calculations on the three-dimensional geometric model, and obtains a target blood flow velocity distribution and a target pressure distribution of the target blood vessel; calculates the blood flow reserve fraction of the target blood vessel based on the target blood flow velocity distribution and the target pressure distribution. This application combines dimensionality reduction simulation with three-dimensional simulation to perform CFD calculation of FFR, and uses the calculation results of dimensionality reduction simulation as initial conditions for three-dimensional simulation, thereby greatly improving the calculation efficiency without affecting the calculation accuracy.

[0193] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated again here.

[0194] Figure 5 It is a schematic diagram of the structure of an electronic device shown in an embodiment of the present application.

[0195] See also Figure 5 , the electronic device 500 includes a memory 510 and a processor 520 .

[0196] The processor 520 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0197] The memory 510 may include various types of storage units, such as system memory, read-only memory (ROM), and permanent storage devices. Among them, ROM can store static data or instructions required by the processor 520 or other modules of the computer. The permanent storage device may be a readable and writable storage device. The permanent storage device may be a non-volatile storage device that does not lose the stored instructions and data even after the computer is powered off. In some embodiments, the permanent storage device uses a large-capacity storage device (such as a magnetic or optical disk, flash memory) as a permanent storage device. In some other embodiments, the permanent storage device may be a removable storage device (such as a floppy disk, an optical drive). The system memory may be a readable and writable storage device or a volatile readable and writable storage device, such as a dynamic random access memory. The system memory may store some or all instructions and data required by the processor at run time. In addition, the memory 510 may include any combination of computer-readable storage media, including various types of semiconductor memory chips (such as DRAM, SRAM, SDRAM, flash memory, programmable read-only memory), and disks and / or optical disks may also be used. In some embodiments, the memory 510 may include a readable and / or writable removable storage device, such as a laser disc (CD), a read-only digital versatile disc (such as a DVD-ROM, a double-layer DVD-ROM), a read-only Blu-ray disc, an ultra-density optical disc, a flash memory card (such as an SD card, a mini SD card, a Micro-SD card, etc.), a magnetic floppy disk, etc. The computer-readable storage medium does not include carrier waves and transient electronic signals transmitted wirelessly or wired.

[0198] The memory 510 stores executable codes, and when the executable codes are processed by the processor 520 , the processor 520 can execute part or all of the methods described above.

[0199] In addition, the method according to the present application may also be implemented as a computer program or a computer program product, which includes computer program code instructions for executing some or all of the steps in the above method of the present application.

[0200] Alternatively, the present application can also be implemented as a computer-readable storage medium (or non-transitory machine-readable storage medium or machine-readable storage medium) on which executable code (or computer program or computer instruction code) is stored. When the executable code (or computer program or computer instruction code) is executed by a processor of an electronic device (or server, etc.), the processor executes part or all of the steps of the above-mentioned method according to the present application.

[0201] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for calculating blood flow reserve fraction, characterized in that: The method comprises: Constructing a three-dimensional geometric model of the target blood vessel; Performing dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel; Using the first blood flow velocity distribution and the first pressure distribution as initial conditions for three-dimensional simulation, performing iterative calculation on the three-dimensional geometric model to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel; The blood flow reserve fraction of the target blood vessel is calculated according to the target blood flow velocity distribution and the target pressure distribution.

2. The method according to claim 1, characterized in that The performing dimension reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel includes: Extracting a three-dimensional center line of the three-dimensional geometric model; wherein the three-dimensional center line includes a plurality of preset points; Extract each cross section perpendicular to the three-dimensional center line at each preset point; Calculating the average blood flow velocity of each cross section; Writing the average blood flow velocity value of each cross section into the three-dimensional center line to obtain a first blood flow velocity distribution of the target blood vessel; Calculating the pressure of each cross section; The pressure values ​​of the respective cross sections are written into the three-dimensional center line to obtain a first pressure distribution of the target blood vessel.

3. The method according to claim 2, characterized in that The calculating the average blood flow velocity of each cross section comprises: Calculating the area of ​​each cross section; Calculating the average cross-sectional area of ​​the target blood vessel according to the areas of the respective cross-sections; determining an average blood flow velocity of the target blood vessel; Calculating the blood flow rate of the target blood vessel according to the average blood flow velocity of the target blood vessel and the average cross-sectional area; The average blood flow velocity of each cross section is calculated according to the blood vessel flow rate of the target blood vessel.

4. The method according to claim 2, characterized in that: The calculating the pressure of each cross section includes: According to the diameter change of the target blood vessel, the target blood vessel is divided into a first blood vessel segment without stenosis characteristics and a second blood vessel segment with stenosis characteristics; wherein the second blood vessel segment includes a first sub-segment with a monotonically decreasing diameter and a second sub-segment with a monotonically increasing diameter; calculating a pressure drop of the first vessel segment, and calculating a pressure drop of the first sub-segment, and calculating a pressure drop of the second sub-segment; The pressure of each cross section is calculated according to the pressure drop of the first blood vessel segment, the pressure drop of the first sub-segment and the pressure drop of the second sub-segment.

5. The method according to claim 2, characterized in that: The first blood flow velocity distribution is used to characterize the distribution of the first blood flow velocity at each preset point, and the first pressure distribution is used to characterize the distribution of the first pressure at each preset point; the first blood flow velocity distribution and the first pressure distribution are used as initial conditions for three-dimensional simulation, and the three-dimensional geometric model is iteratively calculated to obtain the target blood flow velocity distribution and target pressure distribution of the target blood vessel, including: Dividing the grid required for computational fluid dynamics (CFD) calculation based on the three-dimensional geometric model to obtain a three-dimensional grid model of the target blood vessel; Mapping the first blood flow velocity and the first pressure of each preset point to the three-dimensional grid model to obtain the second blood flow velocity and the second pressure represented by each grid node; Determining the second blood flow velocity and the second pressure represented by each grid node as initial conditions for the three-dimensional simulation; The three-dimensional grid model is iteratively calculated based on the initial conditions to obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel.

6. The method according to claim 2, characterized in that The target blood flow velocity distribution is used to characterize the distribution of the target blood flow velocity at each preset point, and the target pressure distribution is used to characterize the distribution of the target pressure at each preset point; and calculating the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution includes: Obtain aortic pressure; The blood flow reserve fraction of the target blood vessel is calculated according to the aortic pressure and the target blood flow velocity and target pressure at each preset point.

7. The method according to claim 1, characterized in that The constructing of the three-dimensional geometric model of the target blood vessel comprises: acquiring multiple angiographic images of the target blood vessel; The target blood vessel is three-dimensionally reconstructed using the multiple angiography images to obtain a three-dimensional geometric model of the target blood vessel.

8. A blood flow reserve fraction calculation device, characterized in that: The device comprises: A three-dimensional construction module, used to construct a three-dimensional geometric model of the target blood vessel; A dimensionality reduction simulation module, used for performing dimensionality reduction simulation on the three-dimensional geometric model to obtain a first blood flow velocity distribution and a first pressure distribution of the target blood vessel; a three-dimensional simulation module, configured to use the first blood flow velocity distribution and the first pressure distribution as initial conditions for three-dimensional simulation, perform iterative calculations on the three-dimensional geometric model, and obtain a target blood flow velocity distribution and a target pressure distribution of the target blood vessel; The blood flow reserve fraction calculation module is used to calculate the blood flow reserve fraction of the target blood vessel according to the target blood flow velocity distribution and the target pressure distribution.

9. An electronic device, characterized in that: include: processor; as well as A memory having executable codes stored thereon, which, when executed by the processor, causes the processor to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having executable codes stored thereon, which, when executed by a processor of an electronic device, causes the processor to execute the method according to any one of claims 1 to 7.

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