CN117174262A - Method for establishing accurate brain stroke computer simulation image model - Google Patents
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Abstract
The invention provides a method for establishing a computer accurate simulation image model of cerebral apoplexy. The method for establishing the accurate brain stroke computer simulation image model comprises the following steps: s1: selecting inclusion patient information: selecting a patient who is involved in acute ischemic stroke, and collecting clinical data, laboratory examinations, clinical function scores and imaging of the patient; s2: imaging analysis: performing head and neck CTP and CTA examinations on the selected patient; s3: imaging three-dimensional reconstruction: adopting three-dimensional reconstruction software MIICS to analyze the infarct core area and ischemic penumbra of a cerebral apoplexy patient, and accurately measuring the corresponding volume and density; s4: based on an imaging hemodynamic assessment. The method for establishing the accurate brain stroke computer simulation image model provides possibility for detailed quantitative evaluation of the illness state of a patient; lays a foundation for the blood flow dynamics change of intracranial arteriosclerosis.
Description
Technical Field
The invention relates to the technical field of medical treatment, in particular to a method for establishing a computer accurate simulation image model for cerebral apoplexy.
Background
Cerebral apoplexy: cerebral stroke is an important disease that is a health hazard. Its high morbidity and high disability rate bring about a heavy burden to society and families. Therefore, the cerebral apoplexy prevention and treatment pressure is huge, and the cerebral apoplexy prevention and treatment method has great economic and social benefits for effective management and control of cerebral apoplexy.
Intracranial atherosclerosis: an important cause of cerebral apoplexy. There is more occurrence of intracranial atherosclerosis in the east asia population than in the western population. Therefore, the structural function and related dangerous factors of the Chinese herbal medicine can be studied, and the occurrence of stroke can be better prevented and treated.
However, in the prior art, the image upgrading of the brain-related functions is realized through biomedical engineering technology and computer technology, and the research is lacking, and the upgradeable analysis is lacking particularly for the important clinical care. Lack of new methods for quantitative diagnosis of disease; the lack of a more intuitive way of observing changes in the imaging architecture, and the lack of a more accurate and efficient method. Accurate measurement of infarct-related areas in stroke patients is lacking.
Therefore, it is necessary to provide a new method for establishing a precise simulated image model of a cerebral apoplexy computer to solve the above technical problems.
Disclosure of Invention
The technical problem solved by the invention is to provide a method for providing possibility for detailed quantitative evaluation of the illness state of a patient; establishes a basic accurate cerebral apoplexy simulation image model establishment method for the blood dynamics change of intracranial arteriosclerosis.
In order to solve the technical problems, the method for establishing the accurate brain stroke computer simulation image model provided by the invention comprises the following steps:
s1: selecting inclusion patient information: selecting a patient who is involved in acute ischemic stroke, and collecting clinical data, laboratory examinations, clinical function scores and imaging of the patient;
s2: imaging analysis: performing head and neck CTA and CTP examinations on the selected patient;
s3: imaging three-dimensional reconstruction: adopting three-dimensional reconstruction software MIICS to analyze the infarct core area and ischemic penumbra of a cerebral apoplexy patient, and accurately measuring the corresponding volume and density;
s4: based on the imaging hemodynamic assessment: hemodynamic measurements were performed using CTA images of the patient to assess the hemodynamic changes in intracranial atherosclerotic stenosis in stroke patients.
Preferably, in the step S1, the clinical data of the patient includes sex, age, contact and other diseases of the patient except for acute ischemic stroke.
Preferably, in the step S3, the three-dimensional imaging reconstruction includes the following steps:
s31: calculating parameters: in the skull CTP, four parameters CBV, CBF, MTT, TTP are respectively analyzed, three-dimensional reconstruction is carried out through MIICS software in the result, and the core density, volume and surface area of different infarcted areas are calculated;
s32: the pretreatment method comprises the following steps: storing the tomographic result in a DICOM format file, then adopting image filtering, image enhancement and image interpolation technology on a preprocessing method, importing the DICOM format file into MIMIICS software, automatically defining left, right, front and back directions in the DICOM format file, and manually defining the top and bottom directions of the tomographic image;
s33: three-dimensional image conversion: in the Mimics3-D function, an original mask is modified by a calculation method through calculation 3D in a dynamic region growth, threshold cut-off and multi-level editing calculation method by means of a 3D interpolation method, contours of all layers are accurately sketched, model operation is started by optimal options, and a two-dimensional image is converted into a 3D model;
s34: image dimension-increasing: and reconstructing a picture by adopting a volume drawing method, automatically forming images of a coronal plane and a sagittal plane by using the cross-sectional picture, and finally exporting the 3D image by using the self-contained export function of the software.
Preferably, in S34, the image dimension-up includes the following steps:
s341: preprocessing an image: preprocessing an image by an image enhancement method, an image filtering method and an image interpolation method;
s342: segmentation of the image: dividing the preprocessed image by a semi-automatic interactive dividing method;
s343: reconstruction display: and drawing the segmented image, including surface drawing and volume drawing.
Preferably, in the step S4, the method further includes the following steps:
s41: three-dimensional reconstruction: three-dimensional reconstruction is carried out through MIICS software, the narrowest position is taken as a comparison group, and stenosis at different positions is artificially constructed through Geomagic studio software; carrying out hydrodynamic calculation on the brain atherosclerosis model by adopting a finite element method;
s42: dividing grids: grid division of the three-dimensional model is completed in an ANSYSTEM workbench, an unstructured tetrahedral grid is adopted, and the overall grid size is set to be 0.5mm after grid dependency verification;
s43: establishing a Carreau model: the Carreau model uses curve fitting to join a newtonian fluid and a shear thinning non-newtonian fluid together;
s44: computational fluid dynamics: computational fluid dynamics analysis was used.
S45: calculating parameters: wall shear stress, time average shear stress, oscillation shear index, relative residence time, average helicity strength.
Preferably, in the step S42, assuming that the vessel wall is not deformed, the blood is an incompressible non-newtonian Carreau fluid, and the power law model of the viscosity of the non-newtonian fluid gives a relationship between the viscosity η and the shear rate γ as follows: when gamma approaches 0, eta approaches eta 0; when γ approaches infinity, η approaches η++.
Preferably, in S43, the specific operation of Carreau model establishment is as follows: and selecting carreau from a pull-down list on the right of the Viscosity, opening the carreau mode panel immediately, inputting a time constant lambda, a power law index n, a reference temperature T0, zero shear Viscosity eta 0 and infinite shear Viscosity eta infinity, and finally calculating the change rule of the hemodynamic parameters under the inlet condition of unsteady speed.
Preferably, in S44, the parameters of the computational fluid dynamics are designed as follows: blood is an incompressible viscous newtonian fluid, density: 1060kg/m3, viscosity 0.0035 Pa.s, and blood flow pattern is laminar.
Compared with the related art, the method for establishing the accurate brain stroke computer simulation image model has the following beneficial effects:
the invention provides a method for establishing a computer accurate simulation image model of cerebral apoplexy, which comprises the steps of simulating and analyzing specific numerical values of density volume and surface area of a core infarction area and an ischemia area of a cerebral arterial thrombosis patient through MIICS software, analyzing differences of different forms, providing more specific numerical values for clinical evaluation thrombolysis and intravascular treatment, guiding clinical practice, and providing more visual data support for prognosis evaluation; visual evaluation of the stenosis of intracranial atherosclerosis of a cerebral apoplexy patient, imaging characteristics and hemodynamic changes are beneficial to evaluating the condition of the patient and assisting clinical diagnosis and treatment; exploring the blood vessel and perfusion related imaging index of cerebral apoplexy patient, providing help for guiding the clinical next practice and prognosis. Can assist in developing new software associated therewith and further provide guidance to the clinician in operation.
Drawings
FIG. 1 is a flow chart of a method for establishing a precise simulation image model of a cerebral apoplexy computer;
fig. 2 is a view of a cta+ctp examination of the head and neck of a patient admitted by a hospital in the method for establishing a computer accurate simulated image model of cerebral apoplexy;
FIG. 3 is a three-dimensional vascular map of a patient reconstructed by using Mimics software according to the method for establishing the accurate brain stroke computer simulation image model;
FIG. 4 is a graph of the common carotid artery, internal carotid artery and external carotid artery remaining after segmentation of the method for establishing a precise simulated image model of a cerebral apoplexy computer provided by the invention;
FIG. 5 is a 3D model diagram of the method for establishing the accurate simulated image model of the cerebral apoplexy computer, which is provided by the invention, wherein the divided blood vessels are calculated to be accurate;
FIG. 6 is a diagram of a vascular model after smoothing in the method for establishing a precise simulated image model of a cerebral apoplexy computer;
FIG. 7 is an optimized view of mesh quality after mesh division of the method for establishing a precise simulation image model of a cerebral apoplexy computer;
FIG. 8 is a wall shear stress diagram of the method for establishing the accurate brain stroke computer simulation image model provided by the invention;
FIG. 9 is a time-averaged shear stress diagram of a method for establishing a computer accurate simulated image model of stroke provided by the invention;
FIG. 10 is a graph of oscillation shear index of the method for establishing a computer accurate simulated image model of cerebral apoplexy provided by the invention;
FIG. 11 is a graph showing the relative residence time of the method for establishing a precise simulated image model of a cerebral apoplexy computer according to the present invention;
fig. 12 is an average helicity intensity diagram of a method for establishing a computer accurate simulation image model of cerebral apoplexy provided by the invention.
Detailed Description
The invention will be further described with reference to the drawings and embodiments.
Referring to fig. 1-12 in combination, fig. 1 is a flowchart of a method for establishing a precise simulation image model of a cerebral apoplexy computer according to the present invention; fig. 2 is a view of a cta+ctp examination of the head and neck of a patient admitted by a hospital in the method for establishing a computer accurate simulated image model of cerebral apoplexy; FIG. 3 is a three-dimensional vascular map of a patient reconstructed by using Mimics software according to the method for establishing the accurate brain stroke computer simulation image model; FIG. 4 is a graph of the common carotid artery, internal carotid artery and external carotid artery remaining after segmentation of the method for establishing a precise simulated image model of a cerebral apoplexy computer provided by the invention; FIG. 5 is a 3D model diagram of the method for establishing the accurate simulated image model of the cerebral apoplexy computer, which is provided by the invention, wherein the divided blood vessels are calculated to be accurate; FIG. 6 is a diagram of a vascular model after smoothing in the method for establishing a precise simulated image model of a cerebral apoplexy computer; FIG. 7 is an optimized view of mesh quality after mesh division of the method for establishing a precise simulation image model of a cerebral apoplexy computer; FIG. 8 is a wall shear stress diagram of the method for establishing the accurate brain stroke computer simulation image model provided by the invention; FIG. 9 is a time-averaged shear stress diagram of a method for establishing a computer accurate simulated image model of stroke provided by the invention; FIG. 10 is a graph of oscillation shear index of the method for establishing a computer accurate simulated image model of cerebral apoplexy provided by the invention; FIG. 11 is a graph showing the relative residence time of the method for establishing a precise simulated image model of a cerebral apoplexy computer according to the present invention;
fig. 12 is an average helicity intensity diagram of a method for establishing a computer accurate simulation image model of cerebral apoplexy provided by the invention. The method for establishing the accurate brain stroke computer simulation image model comprises the following steps:
s1: selecting patients to be taken in: patients who included acute ischemic stroke were selected and relevant clinical data (gender, age, contact, hypertension, diabetes, coronary heart disease, other diseases), laboratory examinations, clinical function scores, imaging data, etc., were collected.
S2: imaging analysis: all patients completed head and neck CTP and CTA examinations,
head and neck CT blood vessel imaging (CTangiography, CTA) is a relatively common blood vessel evaluation tool, and has relatively wide clinical application. It has higher sensitivity and specificity to vascular stenosis, and its main advantage is that imaging is fast, unaffected by motion artefacts [4].
In the occurrence process of cerebral apoplexy, accurate prediction of the dead volume of the infarction and the ischemic penumbra is significant for selecting a proper treatment scheme. At present, in clinic, ischemic penumbra is diagnosed by means of MR perfusion imaging or CT perfusion imaging (CTP) and the like, wherein CTP has the advantages of high resolution, short imaging time, simple operation, low treatment cost and the like, and is favored by clinicians and patients: the brain perfusion condition of the area dominated by the narrow blood vessel can be evaluated in a non-invasive way. The brain CTP can effectively observe the cerebral perfusion condition when the stroke occurs, and can intuitively discover the change of the core area of the infarction and the peripheral ischemic penumbra by means of different sequences.
Parameters of CTP are Cerebral Blood Flow (CBF), cerebral Blood Volume (CBV), mean Transit Time (MTT), and Time To Peak (TTP). CTP functions to reflect intracranial blood perfusion and also to identify reversible ischemia (ischemic penumbra) and irreversibly damaging infarct cores. CTP may show lesions 30min after the onset of acute stroke. The method can accurately detect the infarct core distributed in the range of acute cerebral middle arterial infarction of patients. The "infarct core+penumbra" has higher accuracy, sensitivity and negative predictive value in evaluating cerebral infarction than the infarct core region. There are studies that suggest that CTA and CTP measurements can effectively predict clinical outcome in patients with acute ischemic stroke.
S3: imaging three-dimensional reconstruction, namely, analyzing imaging data by adopting three-dimensional reconstruction software MIICS, analyzing the infarct core area and ischemic penumbra of a cerebral apoplexy patient, and accurately measuring the corresponding volume and density.
As precision treatment goes deeper into the heart, it is particularly important to conduct personalized analysis for each patient. Among image information, images such as CT and MRI are basically a combination of various information, and these are called analog-digital images. Typically, clinical staff rely on layer-by-layer two-dimensional images to assess lesion morphology and size, sometimes making diagnosis and treatment difficult. The advent of new three-dimensional imaging techniques has included more comprehensive information than the original two-dimensional tomographic plane. The 3D image can realize personalized and accurate processing, and the accurate measurement mode is particularly important in modern clinical work.
The method provides more digital objective information for clinical work, adopts a digital method to explore three-dimensional images of the head CTP and the head and neck CTA of a patient, analyzes the changes of the volume, the surface area and the like of related lesion areas, provides an accurate evaluation scheme for each patient, and realizes automatic high-accuracy measurement. The innovation point is mainly that the clinical relevant parameters are obtained through further quantitative analysis, and compared with the conventional image parameters, the clinical prognosis and prognosis conditions of patients can be more intuitively analyzed.
The MIMICS software (materiale' sInteractiveMedicalImageControl Systern, MIMICS) can better handle three-dimensional images. The software is a set of digital medical image software developed by the Material company of Belgium in Europe, and can be highly integrated and edited for three-dimensional images, and is simple and easy to use. The MIICS software can better process the tomographic images, reconstruct the three-dimensional form of the corresponding structure, and has the outstanding function of realizing the evaluation of various parameters, and is simple and direct. The main application process comprises the following steps: first, a three-dimensional finite element model is built, and then an image is converted by a format such as Computer Aided Design (CAD), finite Element Analysis (FEA), and rapid prototyping (Rapid prototyping, RP). At present, MIICS software is mainly applied to orthopedics in the medical field, performs preoperative three-dimensional analysis on orthopedic operations, and is not widely applied to the field of cerebrovascular diseases.
The main advantages of MIMICS software are as follows: DICOM data can be read directly; is simple and practical; the modeling speed is high, and the accuracy is good; simplifying the contour line extraction process; the current animal model cannot completely, accurately and objectively express the pathophysiological process of cerebral apoplexy. Therefore, the novel imaging technology is of great value. In this way, the clinician can more objectively locate, qualitatively and quantitatively analyze the lesion part, and then accurately evaluate the change of the disease by adopting a relevant diagnosis and treatment method and a technology simulation.
S31: calculating parameters: in the skull CTP, four parameters such as CBV, CBF, MTT, TTP and the like are respectively analyzed, three-dimensional reconstruction is carried out through MIICS software in the result, and the core density, volume and surface area of different infarcted areas are calculated.
S32: the pretreatment method comprises the following steps: the tomographic result is stored in a DICOM format file, then the DICOM format file is imported into MIICS software by adopting technologies such as image filtering, image enhancement and image interpolation on a preprocessing method, four orientations such as Left (Left), right (Right), front (Anterior), rear (Posterior) and the like are automatically defined, and two orientations of the Top (Top) and Bottom (Bottom) of the tomographic image are manually defined.
S33: three-dimensional image conversion: in the hybrid 3-D function, by means of a 3D interpolation method, through calculation 3D, an original mask is modified in a dynamic region growing (dynamic region), a threshold cut-off (threshold holding), a multi-level editing (Multiple-slicefit) and other calculation methods, the outline of each layer is accurately sketched, model operation is started through an Optimal option, and the model operation is converted into a 3D model through a two-dimensional image.
S34: image dimension-increasing: and reconstructing the picture by adopting a volume rendering method, wherein the cross-sectional picture can automatically form images of a coronal plane and a sagittal plane. And finally, the 3D image is exported through the export function of the software. We realize the upscaling of the image mainly by the following reconstruction method: A. preprocessing an image: there are methods such as image enhancement, image filtering, image interpolation, etc. B. Segmentation of the image: the accurate reconstructed three-dimensional model can be conveniently and rapidly obtained through a semi-automatic interactive segmentation method. C. Reconstruction display: including surface rendering and volume rendering.
S4: based on the imaging hemodynamic assessment: we used CTA images of patients for hemodynamic measurements to assess the hemodynamic changes in intracranial atherosclerotic stenosis in stroke patients.
S41: three-dimensional reconstruction: three-dimensional reconstruction is carried out through MIICS software, the narrowest position is taken as a comparison group, and stenosis at different positions is artificially constructed through Geomagic studio software; the method is characterized in that a finite element method is adopted to carry out hydrodynamic calculation on a cerebral atherosclerosis model, the three-dimensional structure of intracranial atherosclerosis stenosis of a cerebral apoplexy patient is simulated and analyzed through MIICS software, and the common carotid artery, the internal carotid artery and the external carotid artery which remain after segmentation are obtained. The segmented vessels are computed as an accurate 3D model. And optimizing the grid quality after grid division.
S42: dividing grids: the grid division of the three-dimensional model is completed in an ANSYSTEM workbench, an unstructured tetrahedral grid is adopted, and the global grid size is set to be 0.5mm after grid dependency verification. Assuming that the vessel wall does not deform, the blood is an incompressible non-newtonian Carreau fluid, and the power law model of the viscosity of the non-newtonian fluid gives a viscosity η as a function of shear rate γ: when gamma approaches 0, eta approaches eta 0; when γ approaches infinity, η approaches η++.
S43: establishing a Carreau model: the Carreau model uses curve fitting to combine Newtonian and shear thinning (n < 1) non-Newtonian fluids together to achieve the goal of simulating a wider range of fluid viscosities. The Carreau is selected in a drop down list to the right of the viscocity and the Carreau mode panel is then opened. At this time, a time constant λ, a power law exponent n, a reference temperature T0, a zero shear viscosity η0, and an infinite shear viscosity η+. And finally calculating the change rule of the hemodynamic parameters under the inlet condition of the unsteady speed.
S44: computational fluid dynamics: computational fluid dynamics (Computationalfluid dynamics, CFD) analysis was used: the parameters are designed as follows: blood is an incompressible viscous newtonian fluid, density: 1060kg/m3, viscosity 0.0035 Pa.s, and blood flow pattern is laminar.
S45: calculating parameters: wall Shear Stress (WSS): WSS refers to the shear forces that blood flow produces on the vessel wall, i.e. the frictional forces that blood flow exerts on the vessel wall. Time average shear stress (TAWSS): and the time average shear stress is obtained by integrating the shear stress at each time point in a single cardiac cycle. The distribution characteristics of the average shear stress on the vessel wall over a single cardiac cycle can be analyzed. Oscillation shear index (oscillatory shearindex, OSI): OSI reflects the degree of oscillation of the WSS, i.e. the change in direction of shear stress, in a single cardiac cycle, and the magnitude of OSI may represent the magnitude of the oscillation level of blood flow, i.e. the level of a drastic change in direction of shear stress in a certain cardiac cycle, with values between 0 and 0.5, where a larger value may prove that the WSS changes more severely, and even that reflux occurs. Relative Retention Time (RRT): the relative blocking time represents the dead time of blood around the vessel wall, and the higher the relative blocking time, the longer the blood flow blocking time, the slower the flow rate, and the lower the WSS, which is an indicator of blood flow disturbance. Average helicity intensity (LNH): the temporal and volumetric averages of the inner product norms of the velocity and vorticity vectors at each vessel segment are calculated to quantify the spiral flow and are believed to be important factors in inhibiting blood flow disorders.
The application of Computational Fluid Dynamics (CFD) method in combination with blood vessel imaging to study the hemodynamic state of human blood vessels has been increasingly applied to scientific research and clinic. Computational fluid dynamics is a science of solving a control equation of fluid mechanics by adopting a computer numerical method to simulate and analyze fluid mechanics problems, and comprises a finite element analysis method. Finite element analysis has shown its unique advantages as a new biomechanical research method, which is to solve a mathematical describable physical problem according to the variational principle, and can solve some more complex situations (structure, material properties, load, etc.). Combines finite element analysis method with medical biomechanics or can better solve clinical problems. In the present invention, the corresponding vessels are analyzed and three-dimensional reconstruction is performed by MIMICS software. The non-Newtonian Carreau fluid is adopted, and the power law model of the viscosity of the non-Newtonian fluid is used for giving the change relation of the viscosity eta with the shear rate gamma: gamma tends to 0, eta tends to eta 0; gamma tends to infinity and eta tends to eta infinity. The Carreau model adopts curve fitting to combine Newtonian fluid and shear thinning (n < 1) non-Newtonian fluid to simulate the viscosity of fluid in a larger range, and finally a specific numerical value is obtained through a mathematical calculation formula to guide clinical application.
At present, a mathematical model is developed clinically, the previous research is often developed in the fields of aneurysms, coronary arteries and the like, the method is mature, the operation is simple, and the feasibility is high. The invention aims to study the mathematical model of the blood vessel, provides reference for clinical medicine and has very important practical significance.
Compared with the related art, the method for establishing the accurate brain stroke computer simulation image model has the following beneficial effects:
the invention provides a method for establishing a computer accurate simulation image model of cerebral apoplexy, which comprises the steps of simulating and analyzing specific numerical values of density volume and surface area of a core infarction area and an ischemia area of a cerebral arterial thrombosis patient through MIICS software, analyzing differences of different forms, providing more specific numerical values for clinical evaluation thrombolysis and intravascular treatment, guiding clinical practice, and providing more visual data support for prognosis evaluation; visual evaluation of the stenosis of intracranial atherosclerosis of a cerebral apoplexy patient, imaging characteristics and hemodynamic changes are beneficial to evaluating the condition of the patient and assisting clinical diagnosis and treatment; exploring the blood vessel and perfusion related imaging index of cerebral apoplexy patient, providing help for guiding the clinical next practice and prognosis. Can assist in developing new software associated therewith and further provide guidance to the clinician in operation.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.
Claims (8)
1. The method for establishing the accurate brain stroke computer simulation image model is characterized by comprising the following steps of:
s1: selecting inclusion patient information: selecting a patient who is involved in acute ischemic stroke, and collecting clinical data, laboratory examinations, clinical function scores and imaging of the patient;
s2: imaging analysis: performing head and neck CTP and CTA examinations on the selected patient;
s3: imaging three-dimensional reconstruction: adopting three-dimensional reconstruction software MIICS to analyze the infarct core area and ischemic penumbra of a cerebral apoplexy patient, and accurately measuring the corresponding volume and density;
s4: based on the imaging hemodynamic assessment: hemodynamic measurements were performed using CTA images of the patient to assess the hemodynamic changes in intracranial atherosclerotic stenosis in stroke patients.
2. The method for establishing a computer accurate simulation image model of cerebral apoplexy according to claim 1, wherein in S1, clinical data of the patient includes gender, age, contact information and other diseases of the patient except for acute ischemic cerebral apoplexy.
3. The method for establishing a computer accurate simulation image model for cerebral apoplexy according to claim 1, wherein in S3, the imaging three-dimensional reconstruction comprises the following steps:
s31: calculating parameters: in the skull CTP, four parameters CBV, CBF, MTT, TTP are respectively analyzed, three-dimensional reconstruction is carried out through MIICS software in the result, and the core density, volume and surface area of different infarcted areas are calculated;
s32: the pretreatment method comprises the following steps: storing the tomographic result in a DICOM format file, then adopting image filtering, image enhancement and image interpolation technology on a preprocessing method, importing the DICOM format file into MIMIICS software, automatically defining left, right, front and back directions in the DICOM format file, and manually defining the top and bottom directions of the tomographic image;
s33: three-dimensional image conversion: in the Mimics3-D function, an original mask is modified by a calculation method through calculation 3D in a dynamic region growth, threshold cut-off and multi-level editing calculation method by means of a 3D interpolation method, contours of all layers are accurately sketched, model operation is started by optimal options, and a two-dimensional image is converted into a 3D model;
s34: image dimension-increasing: and reconstructing a picture by adopting a volume drawing method, automatically forming images of a coronal plane and a sagittal plane by using the cross-sectional picture, and finally exporting the 3D image by using the self-contained export function of the software.
4. The method for building a computer accurate simulation image model for cerebral apoplexy according to claim 3, wherein in S34, the image dimension-up comprises the following steps:
s341: preprocessing an image: preprocessing an image by an image enhancement method, an image filtering method and an image interpolation method;
s342: segmentation of the image: dividing the preprocessed image by a semi-automatic interactive dividing method;
s343: reconstruction display: and drawing the segmented image, including surface drawing and volume drawing.
5. The method for establishing a computer accurate simulation image model for cerebral apoplexy according to claim 1, wherein in S4, based on the evaluation of the imaging hemodynamic performance, the method comprises the following steps:
s41: three-dimensional reconstruction: three-dimensional reconstruction is carried out through MIICS software, the narrowest position is taken as a comparison group, and stenosis at different positions is artificially constructed through Geomagic studio software; carrying out hydrodynamic calculation on the brain atherosclerosis model by adopting a finite element method;
s42: dividing grids: grid division of the three-dimensional model is completed in an ANSYSTEM workbench, an unstructured tetrahedral grid is adopted, and the overall grid size is set to be 0.5mm after grid dependency verification;
s43: establishing a Carreau model: the Carreau model uses curve fitting to join a newtonian fluid and a shear thinning non-newtonian fluid together;
s44: computational fluid dynamics: computational fluid dynamics analysis was used.
S45: calculating parameters: wall shear stress, time average shear stress, oscillation shear index, relative residence time, average helicity strength.
6. The method for establishing a computer accurate simulation image model for cerebral apoplexy according to claim 5, wherein in S42, it is assumed that the vessel wall is not deformed, the blood is incompressible non-newton Carreau fluid, and a power law model of viscosity of the non-newton fluid gives a change relation of viscosity η with shear rate γ: when gamma approaches 0, eta approaches eta 0; when γ approaches infinity, η approaches η++.
7. The method for building a computer accurate simulation image model for cerebral apoplexy according to claim 5, wherein in S43, the specific operation of building the Carreau model is: and selecting carreau from a pull-down list on the right of the Viscosity, opening the carreau mode panel immediately, inputting a time constant lambda, a power law index n, a reference temperature T0, zero shear Viscosity eta 0 and infinite shear Viscosity eta infinity, and finally calculating the change rule of the hemodynamic parameters under the inlet condition of unsteady speed.
8. The method for establishing a precise computer simulation image model for cerebral apoplexy according to claim 5, wherein in S44, the parameters of computational fluid mechanics are designed as follows: blood is an incompressible viscous newtonian fluid, density: 1060kg/m3, viscosity 0.0035 Pa.s, and blood flow pattern is laminar.
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