Evaluation method and system for postural cerebral blood flow change, terminal and storage medium

Abstract

The invention discloses a postural cerebral blood flow change assessment method and system, a terminal and a storage medium. The method comprises the steps that cerebrovascular images under different postums are collected, high-precision segmentation is conducted on the cerebrovascular images, three-dimensional cerebrovascular models under the different postums are constructed, and geometric feature information is extracted; according to the geometric feature information, solving a hemodynamic equation in the brain blood vessel by utilizing a computational fluid mechanics method, and calculating to obtain cerebral hemodynamic parameters under different body position conditions in combination with physiological boundary condition changes; the body position related numerical results are compared, blood vessel morphological parameter comparison and hemodynamic parameter comparison are included, and a body position change influence analysis result is obtained. According to the method, the cerebral blood flow characteristics under the lying position and the standing position are compared and analyzed from the two dimensions of morphology and hemodynamics, the influence rule of the position change on the cerebral blood vessel form and blood flow distribution is disclosed, and the understanding of the position-related cerebral hemodynamics change mechanism can be deepened.

Description

Technical Field

[0001] The present invention relates to the technical field of cerebral blood flow simulation, and in particular to a method, system, terminal and computer-readable storage medium for evaluating positional cerebral blood flow changes. Background Art

[0002] The risk of many brain diseases (such as orthostatic hypotension (OH)) is significantly associated with changes in cerebral hemodynamics in patients in different body positions and postures.

[0003] Brain disease is one of the important factors threatening human health, and the occurrence and development of many diseases are closely related to body position. For example, the risk of stroke and orthostatic hypotension is significantly associated with changes in cerebral hemodynamics in individuals under different body positions. Existing clinical studies have shown that orthostatic hypotension is significantly associated with all-cause mortality, coronary heart disease, heart failure and stroke risks. Posture-related brain diseases not only seriously affect the quality of life of patients, but also bring huge medical burdens. Therefore, in-depth research on the impact of body position changes on cerebral blood flow is of great significance to revealing the pathogenesis of these diseases.

[0004] The combination of body position changes and cerebral hemodynamics in existing research is still in the development stage. Direct measurement technology has problems such as complex operation, insufficient data dynamics and accuracy. Although the numerical simulation method based on computational fluid dynamics has potential, it needs to be further expanded and improved in many aspects such as cerebrovascular morphological changes, physiological models and numerical solutions. Therefore, it is impossible to obtain a comprehensive and accurate understanding of the impact of body position on cerebral hemodynamic parameters.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] The main purpose of the present invention is to provide a method, system, terminal and computer-readable storage medium for evaluating positional cerebral blood flow changes, aiming to solve the problem in the prior art that it is impossible to fully and accurately obtain the influence of body position on cerebral hemodynamic parameters.

[0007] To achieve the above object, the present invention provides a method for evaluating positional cerebral blood flow changes, the method comprising the following steps:

[0008] Collecting cerebral vascular images in different body positions, performing high-precision segmentation on the cerebral vascular images in different body positions, constructing three-dimensional cerebral vascular models in different body positions, and extracting geometric feature information;

[0009] Based on the geometric feature information, the hemodynamic equations in the cerebral blood vessels are solved using computational fluid dynamics methods, and the cerebral hemodynamic parameters are calculated under different body position conditions in combination with changes in physiological boundary conditions;

[0010] According to the cerebral hemodynamic parameters, the numerical results related to body position are compared, including the comparison of vascular morphological parameters and hemodynamic parameters, to obtain the analysis results of the influence of body position changes.

[0011] Optionally, the method for evaluating positional cerebral blood flow changes, wherein the steps of collecting cerebral vascular images in different body positions, performing high-precision segmentation on the cerebral vascular images in different body positions, constructing three-dimensional cerebral vascular models in different body positions, and extracting geometric feature information, specifically include:

[0012] Use rotatable magnetic resonance imaging technology to obtain high-resolution cerebral vascular images in different body positions;

[0013] Performing high-precision segmentation of the entire cerebral blood vessels in the cerebral blood vessel images in different body positions by using an image segmentation method, and constructing three-dimensional cerebral blood vessel models in different body positions;

[0014] Based on the three-dimensional cerebral vascular model in different body positions, geometric feature information is extracted.

[0015] Optionally, in the method for evaluating postural cerebral blood flow changes, the body position includes lying down and standing up.

[0016] Optionally, in the method for evaluating postural cerebral blood flow changes, the geometric feature information includes the diameter, curvature and branching structure of the blood vessels.

[0017] Optionally, the method for evaluating the positional cerebral blood flow changes, wherein the hemodynamic equations in the cerebral blood vessels are solved by computational fluid dynamics methods according to the geometric feature information, and the cerebral hemodynamic parameters are calculated under different body position conditions in combination with changes in physiological boundary conditions, specifically includes:

[0018] If blood flow is assumed to be a Newtonian fluid, it is modeled using the three-dimensional unsteady incompressible Navier-Stokes equations:

[0019]

[0020] Where Ω represents the entire three-dimensional computational domain surrounded by the blood vessel geometry, μ represents the blood viscosity coefficient, ρ represents the blood density, u and P represent the velocity vector and pressure to be solved respectively, t represents the time variable, and its value range is in the interval (0, T], T represents the termination time, represents the gradient operator;

[0021] The boundaries of the cerebral blood flow control equation include the inlet, wall, and outlet;

[0022] The inlets include the left carotid artery, the right carotid artery, the left vertebral artery and the right vertebral artery. Indicates that the wall uses Γ W Indicates that the cerebral vascular outlet is the truncation of the distal small blood vessels visible in the image. It is represented by, where m represents the total number of exports;

[0023] For three different boundaries, different boundary conditions are used to meet clinical individual characteristics. Dirichlet boundary conditions and no-slip boundary conditions are set for the inlet and wall respectively:

[0024]

[0025] Among them, v I represents the inlet velocity derived from transcranial Doppler ultrasound measurements, Γ I represents the entrance, Γ W Represents a wall;

[0026] For each outlet, the three-dimensional Windkessel model was selected to obtain the physiological pressure wave;

[0027] The i-th outlet is connected by a capacitor C that reflects the elasticity of the container. i and two resistors representing characteristic resistance and peripheral resistance respectively and composition;

[0028] Among them, the ternary Windkessel model satisfies the following relationship:

[0029]

[0030] Among them, P i (t) and Q i (t) represent the pressure and flow rate of the ith outlet, Indicates the pressure at which flow to the microcirculation ceases;

[0031] In the computational domain of cerebral vessels, the control equations are discretized in space and time using the unstructured finite element method and implicit scheme, respectively, and the control equations are converted into discrete equations that are solved using numerical methods.

[0032] Optionally, the method for evaluating the positional cerebral blood flow changes, wherein the comparison of the numerical results related to the body position is performed according to the cerebral hemodynamic parameters, including the comparison of vascular morphological parameters and the comparison of hemodynamic parameters, to obtain the analysis results of the influence of the body position changes, specifically includes:

[0033] When comparing vascular morphological parameters, the changes in diameter, length, and curvature are considered and analyzed to obtain the comparison results of vascular morphological parameters;

[0034] When comparing hemodynamic parameters, consider analyzing the distribution changes of blood flow pressure, velocity and wall shear force to obtain the hemodynamic parameter comparison results;

[0035] According to the comparison results of the vascular morphological parameters and the comparison results of the hemodynamic parameters, the influence of body position change on hemodynamic characteristics is summarized to obtain the analysis results of the influence of body position change.

[0036] Optionally, the method for evaluating changes in postural cerebral blood flow, wherein when comparing vascular morphological parameters, changes in diameter, length and curvature are considered and analyzed to obtain vascular morphological parameter comparison results, specifically includes:

[0037] In terms of vascular morphology, the reconstructed three-dimensional cerebrovascular model was divided into nine vascular segments, located at the left carotid artery, right carotid artery, left anterior artery, right anterior artery, left middle artery, right middle artery, left posterior artery, right posterior artery and basilar artery;

[0038] For the same vascular segment, the center line of the vascular segment was extracted to obtain the diameter data corresponding to each sampling point along the center line. After processing, the changes in the diameter, length and curvature of the cerebral blood vessels when lying and standing were compared to obtain the comparison results of vascular morphological parameters.

[0039] In addition, to achieve the above-mentioned purpose, the present invention further provides a system for evaluating changes in postural cerebral blood flow, wherein the system for evaluating changes in postural cerebral blood flow comprises:

[0040] An image processing module is used to collect cerebrovascular images in different body positions, perform high-precision segmentation on the cerebrovascular images in different body positions, construct three-dimensional cerebrovascular models in different body positions, and extract geometric feature information;

[0041] A parameter calculation module, for solving the hemodynamic equations in the cerebral blood vessels using a computational fluid dynamics method according to the geometric feature information, and calculating the cerebral hemodynamic parameters under different body position conditions in combination with changes in physiological boundary conditions;

[0042] The parameter comparison module is used to compare the numerical results related to body position according to the cerebral hemodynamic parameters, including the comparison of vascular morphological parameters and hemodynamic parameters, to obtain the analysis results of the impact of body position changes.

[0043] In addition, to achieve the above-mentioned purpose, the present invention also provides a terminal, wherein the terminal includes: a memory, a processor, and an evaluation program for postural cerebral blood flow changes stored in the memory and executable on the processor, wherein the evaluation program for postural cerebral blood flow changes, when executed by the processor, implements the steps of the method for evaluating postural cerebral blood flow changes as described above.

[0044] In addition, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores an evaluation program for postural cerebral blood flow changes, and when the evaluation program for postural cerebral blood flow changes is executed by a processor, the steps of the method for evaluating postural cerebral blood flow changes as described above are implemented.

[0045] In the present invention, cerebrovascular images in different body positions are collected, the cerebrovascular images in different body positions are segmented with high precision, three-dimensional cerebrovascular models in different body positions are constructed, and geometric feature information is extracted; based on the geometric feature information, the hemodynamic equations in the cerebral blood vessels are solved using computational fluid dynamics methods, and combined with changes in physiological boundary conditions, cerebral hemodynamic parameters are calculated under different body position conditions; based on the cerebral hemodynamic parameters, the body position-related numerical results are compared, including vascular morphology parameter comparison and hemodynamic parameter comparison, to obtain the analysis results of the impact of body position changes. The present invention compares and analyzes the cerebral blood flow characteristics in lying and standing positions from the two dimensions of morphology and hemodynamics, reveals the influence of body position changes on cerebrovascular morphology and blood flow distribution, can deepen the understanding of the mechanism of body position-related cerebral hemodynamic changes, and provide data support for further analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of a preferred embodiment of the method for evaluating the change of postural cerebral blood flow of the present invention;

[0047] Figure 2 It is a schematic diagram of a standing medical image and a 3D cerebral vascular model reconstructed in a standing position in a preferred embodiment of the method for evaluating positional cerebral blood flow changes of the present invention;

[0048] Figure 3 It is a schematic diagram of a supine medical image and a 3D cerebral vascular model reconstructed in a supine position in a preferred embodiment of the method for evaluating positional cerebral blood flow changes of the present invention;

[0049] Figure 4 is a schematic diagram of an unstructured grid of cerebral blood vessels and a local part of the grid in a preferred embodiment of the method for evaluating positional cerebral blood flow changes of the present invention;

[0050] Figure 5 It is a structural diagram of a preferred embodiment of the evaluation system of postural cerebral blood flow changes of the present invention;

[0051] Figure 6 It is a structural diagram of a preferred embodiment of the terminal of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] At present, the main technical solutions for studying the effect of body position on individualized cerebral blood flow include:

[0054] (1) Tilt bed test combined with clinical direct measurement technology: This method uses a tilt bed test to place the subject in different body positions, and then uses existing medical equipment to continuously monitor hemodynamic parameters such as cerebral blood flow velocity and blood pressure. The tilt bed test is complex and time-consuming, and the experimental results may be affected by differences in the subject's body position tolerance. In addition, direct measurement technology has limitations in various aspects. As follows:

[0055] 1) Transcranial Doppler ultrasound technology (TCD) is an ultrasound method that uses the naturally weak parts of the human skull as detection windows to detect Doppler signals of intracranial blood flow and obtain hemodynamic parameters of intracranial arteries. Its disadvantage is that it can only measure velocity parameters at a single point, and the operation is highly dependent on the proficiency of the technician.

[0056] 2) Positron Emission Computed Tomography (PET) is a relatively advanced clinical examination imaging technology in the field of nuclear medicine. After glucose or other substances are labeled with short-lived radionuclides and injected into the human body, the accumulation of the substance in metabolism is used to reflect the metabolic activities of life, thereby achieving the purpose of diagnosis. Its disadvantages are high cost, limited image resolution, and insufficient dynamic monitoring capabilities.

[0057] (2) Cardiovascular blood flow model combined with brain autonomic regulation model: The vascular model in this method consists of 11 closed chambers, and the vascular segment is assumed to be an idealized cylinder. It includes two sub-models: the blood flow model, which can predict blood pressure and blood flow velocity when sitting; and the brain autonomic regulation model, which can predict the autonomic nerve and brain regulation mechanism during the posture change from sitting to standing. It can predict the dynamic changes of arterial blood pressure and cerebral blood flow velocity during the transition from sitting to standing. Compared with the direct measurement method, this method can more accurately obtain the hemodynamic parameters in the blood vessels through numerical calculation. However, its simplified vascular geometry is difficult to fully reflect the actual complex physiological structure and dynamic changes.

[0058] (3) Fluid-solid coupling model combined with single-position medical images: The blood flow model in this method is used to simulate the blood flow characteristics in cerebral blood vessels, and the vascular wall model is used to simulate the changes in cerebral vascular morphology under different gravity conditions. Then, numerical calculations are performed based on the vascular model reconstructed from the same medical image. However, it relies on the assumptions of the theoretical model on vascular wall deformation and gravity effects, and may not be able to fully capture the true geometric shape and complex deformation of the blood vessels when the actual body position changes, and the model calculation is complex.

[0059] Although existing technical solutions can obtain the impact of body position changes on cerebral blood flow to varying degrees, they all have certain limitations and it is difficult to fully and accurately explore how body position changes affect individualized cerebral blood flow. Therefore, there is an urgent need for a high-resolution method that can capture the individual characteristics of patients, reveal the influence of body position changes on individualized cerebral vascular morphology and blood flow distribution, and provide reliable quantitative data support for the early diagnosis and personalized treatment of body position-related brain diseases.

[0060] The disadvantages of the prior art mainly include:

[0061] (1) Tilt bed test: The test is complex and time-consuming, and the test results may be affected by differences in the subjects' body position tolerance.

[0062] (2) Transcranial Doppler ultrasound technology: It can only measure velocity parameters at a single point, and the operation is highly dependent on the proficiency of the technician.

[0063] (3) Positron emission tomography technology: high cost, limited image resolution, and insufficient dynamic monitoring capabilities.

[0064] (4) Mathematical model based on simplified vascular geometry: It does not take into account the cerebral vasodilation and contraction caused by changes in body position and the resulting changes in vascular morphology, such as vascular diameter. It ignores the complex geometric characteristics of real blood vessels, such as bifurcation points, curvature changes, local stenosis or dilation, etc. It is difficult to accurately obtain hemodynamic parameters, and it is impossible to formulate individualized and accurate treatment plans.

[0065] (5) Fluid-structure interaction model based on single-position blood vessels: It is impossible to fully capture the true geometric shape and complex deformation of blood vessels when the actual position changes, and it is also impossible to formulate individualized and accurate treatment plans.

[0066] When numerically simulating cerebral hemodynamics based on computational fluid dynamics (CFD) technology, magnetic resonance images are used to reconstruct the three-dimensional cerebral blood vessels of individual patients. Due to technical limitations, magnetic resonance images are usually acquired in the supine position, so the reconstructed cerebral vascular geometry reflects the morphology in the supine position. However, studies have shown that when the human body changes position, the geometric morphology of cerebral blood vessels, such as the diameter, will change. Therefore, if only the image data of the supine position is used for cerebral vascular reconstruction and multi-position cerebral hemodynamic simulation is performed, the simulation accuracy will be affected.

[0067] Existing technical solutions have multiple limitations when studying the effects of changes in body position on cerebral blood flow. First, direct measurement technology has problems such as complex operation, insufficient data dynamics and accuracy, and lacks direct quantification of specific hemodynamic conditions. Secondly, although the numerical simulation method based on computational fluid dynamics has potential, it needs to be further expanded and improved in many aspects such as cerebrovascular morphological changes, physiological models and numerical solutions, and it is impossible to obtain a comprehensive and accurate understanding of the effects of body position on cerebral hemodynamic parameters.

[0068] The present invention combines high-precision anatomical imaging data to construct a cerebral vascular model that can reflect changes in body position. On this basis, from the two dimensions of morphology and hemodynamics, the cerebral blood flow characteristics in lying and standing positions are compared and analyzed to reveal the influence of body position changes on cerebral vascular morphology and blood flow distribution. The present invention can not only deepen the understanding of the mechanism of body position-related cerebral hemodynamic changes, but also provide accurate numerical analysis methods and data support for individualized diagnosis and treatment, and further promote the precision medical research and clinical application of body position-related brain diseases.

[0069] The purpose of the present invention is to solve the above-mentioned shortcomings of the prior art, and specific objectives include:

[0070] (1) Quantification of hemodynamic parameters: Based on computational fluid dynamics methods, the effects of changes in body position on dynamic parameters such as blood flow velocity, pressure distribution, and wall shear stress are quantitatively analyzed, providing a unique perspective for revealing the body position-related cerebral blood flow regulation mechanism.

[0071] (2) Individualized research: Based on rotatable magnetic resonance imaging technology, the key geometric information of cerebral blood vessels in different body postures can be accurately obtained. Through numerical simulation technology, the cerebral blood flow characteristics under changes in body position can be comprehensively and accurately obtained, providing accurate numerical analysis methods and data support for individualized diagnosis and treatment, and further promoting precision medical research and clinical application of brain diseases related to body position.

[0072] The method for evaluating the postural cerebral blood flow changes described in the preferred embodiment of the present invention is as follows: Figure 1As shown, the method for evaluating changes in postural cerebral blood flow comprises the following steps:

[0073] Step S10: collecting cerebral vascular images in different body positions, performing high-precision segmentation on the cerebral vascular images in different body positions, constructing three-dimensional cerebral vascular models in different body positions, and extracting geometric feature information.

[0074] Specifically, rotatable magnetic resonance imaging technology is used to obtain high-resolution cerebral vascular images in different body positions (such as lying and standing, and various other body positions); the entire cerebral blood vessels in the cerebral vascular images in different body positions are segmented with high precision through an image segmentation method to construct a three-dimensional cerebral vascular model in different body positions; based on the three-dimensional cerebral vascular model in different body positions, geometric feature information (such as the diameter, curvature, and branch structure of the blood vessels) is extracted.

[0075] The cerebral vascular models in different positions not only reflect the physiological anatomical structure, but also serve as the calculation domain for hemodynamic calculations, providing necessary geometric information for subsequent CFD analysis. Figure 2 As shown, Figure 2 The left side of the figure shows the standing position medical image. Figure 2 The right side of the figure shows the 3D cerebrovascular model reconstructed in the standing position (i.e., the 3D cerebrovascular model corresponding to standing); Figure 3 As shown, Figure 3 The left side of the figure shows a medical image in a supine position. Figure 3 The right side of the figure shows the 3D cerebrovascular model reconstructed in the supine position (ie, the 3D cerebrovascular model corresponding to the supine position).

[0076] Step S20: according to the geometric feature information, the hemodynamic equations in the cerebral blood vessels are solved by using computational fluid dynamics methods, and the cerebral hemodynamic parameters are calculated under different body positions in combination with changes in physiological boundary conditions.

[0077] Specifically, if the blood flow is assumed to be a Newtonian fluid, the following three-dimensional unsteady incompressible Navier-Stokes equations are used for modeling:

[0078]

[0079] Among them, Ω represents the entire three-dimensional computational domain surrounded by the vascular geometry, μ represents the blood viscosity coefficient, ρ represents the blood density, u and P represent the velocity vector and pressure to be solved respectively, t represents the time variable, and its value range is in the interval (0, T], T represents the termination time, which is usually selected as a multiple of the cardiac cycle. Represents the gradient operator.

[0080] Modeling refers to the use of control equations to simulate blood flow, so as to subsequently solve the control equations to obtain the pressure and velocity of blood flow, while boundary conditions refer to the conditions that need to be met at the boundaries of the computational domain (inlet, outlet, and wall) when solving the control equations.

[0081] The boundary of the above cerebral blood flow control equation is divided into three parts, that is, the boundary of the cerebral blood flow control equation includes the inlet, wall and outlet; after the blood is pumped by the heart, it passes through the ascending aortic arch through four main branches: the left carotid artery, the right carotid artery, the left vertebral artery and the right vertebral artery to supply blood to the brain, that is, the inlet includes the left carotid artery, the right carotid artery, the left vertebral artery and the right vertebral artery. In the control equation, the four inlets are used Indicates that the wall uses Γ W It indicates that due to the limited image accuracy, the cerebral vascular outlet is the truncation of the distal small blood vessels visible in the image. Indicates, where m represents the total number of exports.

[0082] For three different boundaries, different boundary conditions are used to meet clinical individual characteristics. Dirichlet boundary conditions and no-slip boundary conditions are set for the inlet and wall respectively:

[0083]

[0084] Among them, v I represents the inlet velocity derived from transcranial Doppler ultrasound measurements, Γ I represents the entrance, Γ W Represents the wall.

[0085] When simulating blood flow in the cerebral vessels in both lying and standing postures, inlet flow settings that conform to physiological characteristics will be used respectively, and the influence of gravity in different directions will be considered to obtain accurate numerical results.

[0086] For each outlet, the three-element Windkessel model is selected to obtain the physiological pressure wave. The physiological pressure wave is the pressure condition satisfied by the outlet, that is, the outlet boundary condition.

[0087] For example, the i-th outlet is represented by a capacitor C that reflects the elasticity of the container. i and two resistors representing characteristic resistance and peripheral resistance respectively and Composition, parameters of different exports C i , and The settings are made based on their respective geometric characteristics, namely the outlet vessel diameter.

[0088] Among them, the ternary Windkessel model satisfies the following relationship:

[0089]

[0090] Among them, P i (t) and Q i (t) represent the pressure and flow rate of the ith outlet, represents the pressure when the flow to the microcirculation stops. To solve this equation to obtain the boundary conditions of the outlet, it is necessary to give the initial conditions of velocity and pressure, which are assumed to be 0.

[0091] In the computational domain of cerebral blood vessels, the control equations are discretized in space and time using the unstructured finite element method and implicit scheme, respectively. The discretization is to transform the control equations that are difficult to solve analytically into discrete equations that can be solved using numerical methods.

[0092] Since the anatomical structure of cerebral blood vessels is very complex, traditional structured grids (such as rectangular or cubic grids) are difficult to adapt to irregular vascular morphology. Therefore, the use of unstructured grids (in three dimensions, unstructured grids are composed of arbitrary polyhedral units, which are suitable for complex and irregular geometric domains and can accurately describe the geometric characteristics of cerebral blood vessels; these units are the basic units of numerical calculations, and the nodes of each unit are the distribution positions of the spatial variables after discretization) can more flexibly adapt to complex geometric shapes, especially in vascular systems such as cerebral blood vessels that have twists and branches. In terms of time discretization, considering the overall timeliness of cerebral blood flow simulation, it is proposed to use an implicit format for discretization. For example Figure 4 As shown, Figure 4 The left side of the figure shows an unstructured mesh of cerebral blood vessels. Figure 4 The right side of represents the local grid.

[0093] Step S30: comparing the numerical results related to body position according to the cerebral hemodynamic parameters, including the comparison of vascular morphological parameters and hemodynamic parameters, to obtain the analysis results of the influence of body position changes.

[0094] Specifically, the comparison of body position-related numerical results can be divided into two parts: vascular morphology and hemodynamic parameter comparison. When comparing vascular morphology parameters, the changes in diameter, length and curvature are considered to be analyzed to obtain the vascular morphology parameter comparison results; when comparing hemodynamic parameters, the distribution changes in blood flow pressure, velocity and wall shear force are considered to be analyzed to obtain the hemodynamic parameter comparison results; based on the vascular morphology parameter comparison results and the hemodynamic parameter comparison results, the effects of body position changes on hemodynamic characteristics are summarized to obtain the analysis results of the effects of body position changes, providing a basis for further research and clinical application.

[0095] Among them, in terms of vascular morphology, the reconstructed three-dimensional cerebral vascular model is divided into 9 vascular segments, which are located at the left carotid artery, right carotid artery, left anterior artery, right anterior artery, left middle artery, right middle artery, left posterior artery, right posterior artery and basilar artery; for the same vascular segment, the center line of the vascular segment is extracted to obtain the diameter data corresponding to each sampling point along the center line. After processing, the changes in the diameter, length and curvature of the cerebral blood vessels when lying and standing are compared to obtain the comparison results of vascular morphology parameters. For hemodynamic parameters, the present invention intends to compare representative parameters such as pressure, flow velocity, wall shear force, etc. at each point in the vascular calculation domain, so as to obtain the comparison results of hemodynamic parameters.

[0096] The present invention can realize high-precision cerebral hemodynamic analysis, obtain high-resolution, multi-modal cerebral vascular images through rotatable magnetic resonance imaging technology, support repeated scanning in different body positions such as standing and lying, extract the geometric characteristics of cerebral blood vessels (such as arterial diameter, curvature, branch structure) from the image data, and convert these geometric information into a hemodynamic model through computational fluid dynamics methods, and perform numerical solution, thereby providing more comprehensive and accurate cerebral hemodynamic information.

[0097] The present invention sets individualized boundary conditions in combination with clinical measurement data to ensure the physiological fit of the simulation. At the same time, the influence of body position changes on cerebral vascular morphology and gravity is considered, and the boundary conditions are dynamically adjusted to reflect the influence of actual body position on blood flow distribution. The regulation mechanism of individualized cerebral blood flow in dynamic body position changes is deeply analyzed.

[0098] The key points of the present invention are as follows:

[0099] (1) The key geometric information of cerebral blood vessels in different body positions can be accurately obtained by using rotatable magnetic resonance imaging technology. Based on this, the three-dimensional model of cerebral blood vessels in different body positions can be reconstructed to ensure the comprehensiveness and accuracy of the geometric information.

[0100] (2) Combined with computational fluid dynamics methods, it is possible to quantitatively analyze the impact of changes in body position on dynamic parameters such as blood flow velocity, pressure distribution, and wall shear stress.

[0101] (3) The inlet boundary conditions are set based on clinical measurement data to ensure that the simulated physiological process is highly consistent with the actual physiological state, thereby improving the accuracy and reliability of the simulation results.

[0102] (4) Consider the impact of body position changes on cerebral vascular morphology and gravity, and dynamically adjust the boundary conditions during the simulation process accordingly. Accurately simulate and analyze the changes in cerebral blood flow in different body positions, thereby revealing the complex mechanism of cerebral blood flow regulation and providing strong support for clinical diagnosis and treatment.

[0103] Compared with the existing method based on computational fluid dynamics to explore the effect of body position change on cerebral blood flow, the present invention has significant advantages in many aspects. The following are the main advantages of the present invention over the prior art:

[0104] (1) Reconstruction of multi-position cerebrovascular model:

[0105] The simplified vascular geometry or vascular models based on a single body position in the prior art cannot accurately reflect the morphological changes of actual blood vessels, and cannot fully capture the dynamic effects of body position changes on blood flow. The present invention uses rotatable magnetic resonance imaging technology to obtain high-resolution cerebral vascular imaging data, and uses advanced image segmentation methods to perform high-precision segmentation of the entire cerebral blood vessels, extract key geometric features, and construct a three-dimensional cerebral vascular model in different body positions. This step ensures that the model can accurately reflect the individualized cerebral vascular characteristics of the patient, providing a solid foundation for subsequent hemodynamic simulation.

[0106] Effect: It can accurately obtain the key geometric information of cerebral blood vessels in different body positions, improve the resolution and accuracy of the cerebral vascular model, make the simulation results closer to the actual situation, and provide a reliable basis for individualized medical diagnosis or treatment planning.

[0107] (2) Individualized cerebral hemodynamic simulation consistent with physiological characteristics:

[0108] Existing technologies are difficult to use for individualized medical diagnosis or treatment planning. The present invention uses computational fluid dynamics methods to solve the hemodynamic equations (such as the Navier-Stokes equations) in cerebral blood vessels. During the simulation process, the changes in physiological boundary conditions, such as the effects of changes in body position on parameters such as blood pressure and heart rate, are fully considered. This allows the simulation results to accurately reflect the changes in cerebral hemodynamic parameters under different body positions.

[0109] Effect: The accurate calculation of cerebral hemodynamic parameters is achieved, which provides strong support for revealing the influence of body position changes on individualized cerebral vascular morphology and blood flow distribution. At the same time, it also provides reliable quantitative data for the early diagnosis and personalized treatment of body position-related brain diseases.

[0110] The present invention has been preliminarily verified in actual clinical environments. For example, in cooperation with a certain hospital, a real patient was selected and the cerebral hemodynamic simulation calculations were performed when standing and lying down through brain magnetic resonance imaging and the corresponding physiological data of blood pressure and heart rate. The morphological parameters and hemodynamic parameters were effectively compared, showing good feasibility and practicality.

[0111] Furthermore, the present invention also provides a variety of alternatives as follows:

[0112] (1) Alternative 1: Geometric data acquisition combining multimodal images.

[0113] In addition to the three-dimensional model constructed based on the rotatable magnetic resonance data of cerebral blood vessels, the present invention can also be combined with other types of imaging data for multimodal comprehensive analysis. For example, imaging data such as computed tomography angiography (CTA) and echocardiography can further supplement the anatomical structure and functional information of cerebral blood vessels. Combining multimodal medical images can provide more comprehensive vascular information and further improve accuracy. Design change: Combine rotatable magnetic resonance imaging with multimodal images such as CTA and echocardiography to enhance the detail capture capability of the cerebral vascular model and comprehensively establish an individualized cerebral vascular model.

[0114] (2) Alternative 2: Automated modeling based on deep learning.

[0115] The present invention currently uses an image segmentation algorithm to process the rotatable magnetic resonance imaging data of cerebral blood vessels to construct a three-dimensional geometric model. In order to further improve the efficiency and accuracy of model construction, the present invention can automatically process the image data and automatically generate a cerebral vascular model by integrating deep learning technology, such as a deep convolutional neural network. This method can reduce manual intervention and improve the accuracy of image segmentation. Design change: Use a deep learning model to automatically process the rotatable magnetic resonance data of cerebral blood vessels, automatically segment the vascular area, and generate a personalized three-dimensional model, thereby optimizing the current manual operation process and further improving the efficiency and accuracy of the evaluation.

[0116] (3) Alternative 3: Replace and optimize boundary conditions.

[0117] The present invention currently uses a ternary Windkessel model to simulate the outlet boundary conditions. In order to be able to more accurately simulate the characteristics of a complex microcirculatory system. The present invention can further use a higher-order Windkessel model to describe the dynamic changes and nonlinear characteristics of the vascular system, so as to better simulate the outlet boundary conditions. In addition, the present invention can also use a machine learning algorithm to learn the pressure-flow relationship at the outlet from a large amount of physiological data to establish a more accurate individualized boundary condition model. Design change: For the outlet boundary conditions, a higher-order Windkessel model is used for simulation. Or use a machine learning algorithm to learn the pressure-flow relationship at the outlet from a large amount of physiological data to establish a more accurate individualized boundary condition model.

[0118] (4) Alternative 4: Multidimensional data analysis and personalized risk assessment.

[0119] In the result comparison and analysis stage, the present invention adopts a direct comparison of vascular morphological parameters and hemodynamic parameters. In order to more deeply explore the complex pattern of the impact of body position changes on cerebral blood flow. The present invention can introduce multidimensional data analysis methods, such as principal component analysis, cluster analysis or machine learning algorithms. At the same time, based on the simulation results, personalized risk assessment tools can be developed to provide more specific suggestions for early warning and personalized treatment of body position-related brain diseases. Design changes: Introduce multidimensional data analysis methods to explore the complex pattern of the impact of body position changes on cerebral blood flow; develop personalized risk assessment tools to provide guidance for early warning and treatment of body position-related brain diseases.

[0120] (5) Alternative 5: Cerebrovascular risk assessment for different types of surgery.

[0121] The present invention is currently used to explore the effects of changes in body position on cerebral blood flow. However, its technical principles are also applicable to simulating and comparing the effects of different surgical plans on cerebral blood flow, providing doctors with more intuitive and accurate surgical planning and simulation tools. Design changes: Construct a patient-specific cerebrovascular model to simulate the effects of different surgical plans on cerebral blood flow. By adjusting parameters such as the surgical path and resection range, observe changes in cerebral blood flow, including key parameters such as blood flow velocity and pressure distribution.

[0122] Furthermore, if Figure 5 As shown, based on the above-mentioned method for evaluating positional cerebral blood flow changes, the present invention also provides a system for evaluating positional cerebral blood flow changes, wherein the system for evaluating positional cerebral blood flow changes comprises:

[0123] An image processing module 51 is used to collect cerebrovascular images in different body positions, perform high-precision segmentation on the cerebrovascular images in different body positions, construct three-dimensional cerebrovascular models in different body positions, and extract geometric feature information;

[0124] A parameter calculation module 52 is used to solve the hemodynamic equations in the cerebral blood vessels using a computational fluid dynamics method according to the geometric feature information, and calculate the cerebral hemodynamic parameters under different body position conditions in combination with changes in physiological boundary conditions;

[0125] The parameter comparison module 53 is used to compare the numerical results related to body position according to the cerebral hemodynamic parameters, including the comparison of vascular morphological parameters and hemodynamic parameters, to obtain the analysis results of the influence of body position changes.

[0126] Furthermore, if Figure 6 As shown, based on the above-mentioned method and system for evaluating postural cerebral blood flow changes, the present invention also provides a terminal accordingly, and the terminal includes a processor 10, a memory 20 and a display 30. Figure 6Only some components of the terminal are shown, but it should be understood that it is not required to implement all of the components shown, and more or fewer components may be implemented instead.

[0127] In some embodiments, the memory 20 may be an internal storage unit of the terminal, such as a hard disk or memory of the terminal. In other embodiments, the memory 20 may also be an external storage device of the terminal, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), etc. equipped on the terminal. Further, the memory 20 may also include both an internal storage unit of the terminal and an external storage device. The memory 20 is used to store application software and various types of data installed in the terminal, such as the program code of the installation terminal. The memory 20 may also be used to temporarily store data that has been output or is to be output. In one embodiment, the memory 20 stores an evaluation program 40 for changes in postural cerebral blood flow, which may be executed by the processor 10, thereby realizing the evaluation method for changes in postural cerebral blood flow in the present application.

[0128] In some embodiments, the processor 10 may be a central processing unit (CPU), a microprocessor or other data processing chip, used to run the program code or process data stored in the memory 20, such as executing the method for evaluating postural cerebral blood flow changes.

[0129] In some embodiments, the display 30 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch device, etc. The display 30 is used to display information on the terminal and to display a visual user interface. The components 10-30 of the terminal communicate with each other via a system bus.

[0130] In one embodiment, when the processor 10 executes the postural cerebral blood flow change assessment program 40 in the memory 20 , the steps of the postural cerebral blood flow change assessment method as described above are implemented.

[0131] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a program for evaluating postural cerebral blood flow changes, and when the program for evaluating postural cerebral blood flow changes is executed by a processor, the steps of the method for evaluating postural cerebral blood flow changes as described above are implemented.

[0132] In summary, the present invention provides an evaluation method, system, terminal and storage medium for positional cerebral blood flow changes, the method comprising: collecting cerebral vascular images in different body positions, performing high-precision segmentation on the cerebral vascular images in different body positions, constructing three-dimensional cerebral vascular models in different body positions, and extracting geometric feature information; according to the geometric feature information, using computational fluid dynamics to solve the hemodynamic equations in the cerebral blood vessels, combining the changes in physiological boundary conditions, and calculating the cerebral hemodynamic parameters under different body position conditions; according to the cerebral hemodynamic parameters, comparing the body position-related numerical results, including the comparison of vascular morphological parameters and the comparison of hemodynamic parameters, to obtain the analysis results of the impact of body position changes. The present invention compares and analyzes the cerebral blood flow characteristics in lying and standing positions from the two dimensions of morphology and hemodynamics, reveals the influence of body position changes on cerebral vascular morphology and blood flow distribution, can deepen the understanding of the mechanism of body position-related cerebral hemodynamic changes, and provide data support for further analysis.

[0133] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or terminal including the element.

[0134] Of course, those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware (such as a processor, a controller, etc.) through a computer program, and the program can be stored in a computer-readable storage medium that can be read by a computer, and the program can include the processes of the above-mentioned method embodiments when executed. The computer-readable storage medium can be a memory, a disk, an optical disk, etc.

[0135] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for evaluating postural cerebral blood flow changes, characterized in that: The method for evaluating the postural cerebral blood flow changes includes: Collecting cerebral vascular images in different body positions, performing high-precision segmentation on the cerebral vascular images in different body positions, constructing three-dimensional cerebral vascular models in different body positions, and extracting geometric feature information; Based on the geometric feature information, the hemodynamic equations in the cerebral blood vessels are solved by using computational fluid dynamics methods, and the cerebral hemodynamic parameters are calculated under different body position conditions in combination with changes in physiological boundary conditions; According to the cerebral hemodynamic parameters, the numerical results related to body position are compared, including the comparison of vascular morphological parameters and hemodynamic parameters, to obtain the analysis results of the influence of body position changes.

2. The method for evaluating postural cerebral blood flow changes according to claim 1, characterized in that: The collecting of cerebral vascular images in different body positions, performing high-precision segmentation on the cerebral vascular images in different body positions, constructing three-dimensional cerebral vascular models in different body positions, and extracting geometric feature information specifically includes: Use rotatable magnetic resonance imaging technology to obtain high-resolution cerebral vascular images in different body positions; Performing high-precision segmentation of the entire cerebral blood vessels in the cerebral blood vessel images in different body positions by using an image segmentation method, and constructing three-dimensional cerebral blood vessel models in different body positions; Based on the three-dimensional cerebral vascular model in different body positions, geometric feature information is extracted.

3. The method for evaluating postural cerebral blood flow changes according to claim 2, characterized in that: The body positions include lying down and standing.

4. The method for evaluating postural cerebral blood flow changes according to claim 2, characterized in that: The geometric feature information includes the diameter, curvature and branch structure of the blood vessel.

5. The method for evaluating postural cerebral blood flow changes according to claim 1, characterized in that: The hemodynamic equations in the cerebral blood vessels are solved by using computational fluid dynamics methods according to the geometric feature information, and the cerebral hemodynamic parameters are calculated under different body positions in combination with changes in physiological boundary conditions. Specifically, the following are included: If blood flow is assumed to be a Newtonian fluid, it is modeled using the three-dimensional unsteady incompressible Navier-Stokes equations: Where Ω represents the entire three-dimensional computational domain surrounded by the blood vessel geometry, μ represents the blood viscosity coefficient, ρ represents the blood density, u and P represent the velocity vector and pressure to be solved respectively, t represents the time variable, and its value range is in the interval (0, T], T represents the termination time, represents the gradient operator; The boundaries of the cerebral blood flow control equation include the inlet, wall, and outlet; The inlets include the left carotid artery, the right carotid artery, the left vertebral artery and the right vertebral artery. Indicates that the wall uses Γ W Indicates that the cerebral vascular outlet is the truncation of the distal small blood vessels visible in the image. It is represented by, where m represents the total number of exports; For three different boundaries, different boundary conditions are used to meet clinical individual characteristics. Dirichlet boundary conditions and no-slip boundary conditions are set for the inlet and wall respectively: Among them, v I represents the inlet velocity derived from transcranial Doppler ultrasound measurements, Γ I represents the entrance, Γ W Represents a wall; For each outlet, the three-dimensional Windkessel model was selected to obtain the physiological pressure wave; The i-th outlet is connected by a capacitor C that reflects the elasticity of the container. i and two resistors representing characteristic resistance and peripheral resistance respectively and composition; Among them, the ternary Windkessel model satisfies the following relationship: Among them, P i (t) and Q i (t) represent the pressure and flow rate of the ith outlet, Indicates the pressure at which flow to the microcirculation ceases; In the computational domain of cerebral vessels, the control equations are discretized in space and time using the unstructured finite element method and implicit scheme, respectively, and the control equations are converted into discrete equations that are solved using numerical methods.

6. The method for evaluating postural cerebral blood flow changes according to claim 1, characterized in that: The comparison of the body position related numerical results based on the cerebral hemodynamic parameters, including the comparison of vascular morphological parameters and hemodynamic parameters, to obtain the analysis results of the impact of body position changes, specifically includes: When comparing vascular morphological parameters, the changes in diameter, length, and curvature are considered and analyzed to obtain the comparison results of vascular morphological parameters; When comparing hemodynamic parameters, consider analyzing the distribution changes of blood flow pressure, velocity and wall shear force to obtain the hemodynamic parameter comparison results; According to the comparison results of the vascular morphological parameters and the comparison results of the hemodynamic parameters, the influence of body position change on hemodynamic characteristics is summarized to obtain the analysis results of the influence of body position change.

7. The method for evaluating postural cerebral blood flow changes according to claim 6, characterized in that: When comparing the vascular morphological parameters, the changes in diameter, length and curvature are considered and analyzed to obtain the vascular morphological parameter comparison results, which specifically include: In terms of vascular morphology, the reconstructed three-dimensional cerebrovascular model was divided into nine vascular segments, located at the left carotid artery, right carotid artery, left anterior artery, right anterior artery, left middle artery, right middle artery, left posterior artery, right posterior artery and basilar artery; For the same vascular segment, the center line of the vascular segment was extracted to obtain the diameter data corresponding to each sampling point along the center line. After processing, the changes in the diameter, length and curvature of the cerebral blood vessels when lying down and standing were compared to obtain the comparison results of vascular morphological parameters.

8. A system for evaluating postural cerebral blood flow changes, characterized in that: The evaluation system of postural cerebral blood flow changes includes: An image processing module is used to collect cerebrovascular images in different body positions, perform high-precision segmentation on the cerebrovascular images in different body positions, construct three-dimensional cerebrovascular models in different body positions, and extract geometric feature information; A parameter calculation module, for solving the hemodynamic equations in the cerebral blood vessels using a computational fluid dynamics method according to the geometric feature information, and calculating the cerebral hemodynamic parameters under different body position conditions in combination with changes in physiological boundary conditions; The parameter comparison module is used to compare the numerical results related to body position according to the cerebral hemodynamic parameters, including the comparison of vascular morphological parameters and hemodynamic parameters, to obtain the analysis results of the impact of body position changes.

9. A terminal, characterized in that: The terminal includes: a memory, a processor, and a program for evaluating postural cerebral blood flow changes stored in the memory and executable on the processor. When the program for evaluating postural cerebral blood flow changes is executed by the processor, the steps of the method for evaluating postural cerebral blood flow changes as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program for evaluating postural cerebral blood flow changes, and when the program for evaluating postural cerebral blood flow changes is executed by a processor, the steps of the method for evaluating postural cerebral blood flow changes as described in any one of claims 1 to 7 are implemented.

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