CN113033121B - Method for selecting diameter of portal hypertension transjugular intrahepatic portosystemic shunt stent - Google Patents
Method for selecting diameter of portal hypertension transjugular intrahepatic portosystemic shunt stent Download PDFInfo
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Abstract
The invention discloses a method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt bracket, which relates to the technical field of medical instruments and comprises the following steps: reconstructing a hepatic vein-portal vein system three-dimensional solid model through imaging control software, establishing a finite element computing platform comprising a geometric model module, a hydrodynamics computing module and a post-processing module, importing the hepatic vein-portal vein system three-dimensional solid model, adding supports with different diameters into the model to simulate a TIPS (TIPS surgery for surgery) model, dividing blood grids and setting parameters; obtaining pressure distribution and blood flow distribution of the three-dimensional blood vessel model; and obtaining a TIPS postoperative portal vein pressure gradient value of the three-dimensional blood vessel model. The most suitable stent is selected by comparing the blood pressure reduction effects of stents with different diameters, a new idea is provided for the selection of the diameter of the TIPS surgical stent, and the improvement of the life quality of patients and the reduction of the occurrence risk of complications are promoted.
Description
Technical Field
The invention relates to the technical field of medical instruments, in particular to a method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent.
Background
Portal hypertension is an important factor affecting the clinical prognosis of patients with liver cirrhosis, and the severity of portal hypertension determines the occurrence and development of complications of liver cirrhosis (such as bleeding due to esophageal and gastric varices rupture, etc.). Transjugular Intrahepatic Portosystemic Shunt (TIPS) is one of the key measures to reduce portal vein pressure in patients with cirrhosis by establishing a shunt within the hepatic parenchyma between the hepatic vein and the portal vein in a minimally invasive manner, thereby significantly reducing portal vein resistance structurally. Compared with the drug therapy and the endoscopic therapy, TIPS can substantially reduce portal vein pressure and is an effective means for solving esophageal and gastric variceal bleeding.
At present, TIPS has been widely used for treating esophageal and gastric variceal bleeding, refractory hydrothorax and ascites, hepatic sinus obstruction syndrome and the like caused by hepatic cirrhosis portal hypertension. After continuous exploration and development for 30 years, particularly along with clinical application of a special coated stent, china has relatively comprehensive knowledge on the aspects of indications, contraindications, technical operation standards, postoperative complications and the like of TIPS. However, precise planning before TIPS surgery, especially the individual selection of stent diameter, is always a hotspot and difficulty in the field.
After the TIPS portal channel is established, portal vein pressure gradient (PPG) is obtained by measuring portal vein pressure and inferior vena cava pressure at baseline level and calculating the pressure difference between the portal vein and inferior vena cava. Balloon catheter dilatation and endoluminal stenting were then performed, and post-operative PPG was measured and calculated again. The TIPS clinical practice guidelines in China point out: when post-operative PPG is reduced to 12mmHg or below, the risk of varicose reoccurrence is significantly reduced; in addition, a reduction in post-operative PPG by more than 50% from baseline levels may also significantly reduce the risk of variceal rebleeding.
The choice of scaffold diameter (e.g., 6mm, 7mm, 8mm and 10 mm) in clinical practice will significantly affect the size of the post-operative PPG: if the diameter is selected to be smaller, the portal vein pressure cannot be effectively reduced, and the expected effect of the operation cannot be achieved; if the diameter is selected to be larger, the stent is shunted too much, and the occurrence risk of hepatic encephalopathy, even hepatic myelopathy, is obviously increased. Therefore, the choice of TIPS scaffold diameter is directly related to the interventional procedure outcome and the clinical prognosis of the patient.
Currently, 8mm stents are often preferred in clinical practice. However, a single diameter stent is not suitable for all patients with portal hypertension. In addition, some interventionalists still select stents by clinical experience, and the method depends on the subjective experience of operators and has no standardized quality control. This can be a risk for poor prognosis in patients once the stent has not achieved the desired hypotensive effect (post-operative PPG reduction to 12mmHg or less, or post-operative PPG reduction by more than 50% from baseline). If the stent is taken out and is re-placed into stents with different diameters, the operation risk is greatly increased, and huge economic burden is brought to patients. Therefore, the individual selection of the diameter of the stent before the TIPS operation is of great importance, and the stent with the small diameter should be selected as far as possible on the premise of ensuring the blood pressure reduction effect so as to reduce the occurrence risk of the operation complications.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent, and aims to enable the diameter of a TIPS stent to be capable of being individually designed and realize the accurate selection of the diameter of the TIPS stent.
The invention is realized by the following steps:
the embodiment of the invention provides a method for selecting the diameter of a portal vein high-pressure transjugular intrahepatic portosystemic shunt stent, which is characterized in that a hepatic vein-portal vein system three-dimensional model of stents with different diameters is established by using imaging control software and modeling software, portal vein pressure values before and after a simulation operation are simulated by using a finite element computing platform, and the diameter of the stent is selected.
The invention has the following beneficial effects: the accurate hepatic vein-portal vein system three-dimensional models of the stents with different diameters are reconstructed through the imaging control and modeling software, a standardized hydrodynamics simulation analysis process is established by utilizing a finite element computing platform, a new thought is provided for the selection of the diameters of the TIPS operation stents, the life quality of a patient is improved, and the occurrence risk of complications is reduced.
The present invention is not intended for diagnosis and treatment of diseases.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 shows the sequence of the CTA layer in hepatic venous phase introduced in MIMICS, with a layer thickness of 1.25mm and a resolution of 512x 512 pixels;
FIG. 2 is a diagram illustrating the arrangement of the layer sequence in the software;
FIG. 3 is a coronal, sagittal and horizontal images automatically generated by software;
FIG. 4 sets threshold ranges for a threshold algorithm tool;
FIG. 5 targets selected for the Region growing tool;
FIG. 6 is a plot of the size 3D from mask (three dimensional modeling), with medium precision selected;
FIG. 7 is a schematic diagram of the establishment of a preliminary hepatic-portal vein system;
FIG. 8 shows that the Crop mask tool further extracts target structures and rejects some non-target structures;
FIG. 9 is a three-dimensional model remaining after operation of the Crop mask tool;
FIG. 10 is an Edit masks in 3D tool with residual non-target structures removed;
FIG. 11 is the hepatic vein-portal vein system remaining after the operation of the Edit masks in 3D tool;
FIG. 12 is a diagram of a hepatic vein-portal vein solid model after repeated operation using the Edit masks in 3D (three-dimensional editing mask) tool and the Edit masks tool of MIMICS;
FIG. 13 is a selection of a model after smoothing operation, inp format derivation;
FIG. 14 is an open geometric model simulating pre-operative portal venous pressure;
FIG. 15 is a three-dimensional model after the addition of a virtual stent (post-operative);
FIG. 16 is a solid model body for face-based modeling of the hepatic vein-portal vein system (post-operative);
FIG. 17 is an ANSYS Workbench finite element analysis computing platform;
FIG. 18 is a setup platform for setup solution;
FIG. 19 is a solution unit interface;
FIG. 20 is a diagram of setting solution control parameters and the number of iterations;
FIG. 21 is a graph of pressure distribution and blood flow distribution solved to obtain a simulated three-dimensional vessel model;
FIG. 22 is a pre-operative portal pressure simulation and pressure distribution plot;
FIG. 23 is a post-operative portal pressure simulation and pressure distribution plot;
fig. 24 is a hydromechanical simulation calculation result of PPG after virtual TIPS surgery.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The embodiment of the invention provides a method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt bracket, which reconstructs accurate hepatic vein-portal vein system three-dimensional models of brackets with different diameters through imaging control and modeling software and utilizes a finite element computing platform to construct a standardized hydrodynamics simulation analysis process. The method specifically comprises the following steps:
s1, establishing three-dimensional model of hepatic vein-portal vein system
And (3) introducing imaging control software to obtain a hepatic vein-portal vein system three-dimensional model by using a CTA hepatic vein phase layer sequence. A CTA image layer sequence including hepatic venous phase is acquired, and the image layer sequence is derived in the format dicom with a layer thickness of 1.25mm and an image resolution of 512 × 512 pixels, as shown in fig. 1.
In some embodiments, the employed imaging control software is MIMICS software, and the process of establishing the three-dimensional model of the hepatic vein-portal vein system includes:
(1) Importing the obtained CTA data into MIMICS software, selecting a hepatic vein phase layer sequence, and setting the orientation of the image sequence, as shown in FIG. 2; MIMICS software automatically recognizes the image sequence and generates images of the coronal, sagittal and horizontal positions of the hepatic venous phase CTA image sequence, as shown in fig. 3.
(2) Searching in the image by taking the hepatic vein-portal vein system as a target, setting a threshold range extraction target (as shown in figure 4) by utilizing a threshold algorithm tool in MIMICS software, and setting a threshold to take the CT value of the target as far as possible and the CT value of the peripheral liver and other soft tissues close to the target as far as possible as excluded as possible as a principle. Selecting a target by using a Region growing tool in MIMICS software to extract a structure which is only connected with the target in a space structure (as shown in FIG. 5); a preliminary hepatic vein-portal vein three-dimensional model (as shown in FIGS. 6 and 7) is established by using a model 3D from mask tool in MIMICS software.
In some preferred embodiments, the quality is selected as medium in the preliminary hepatic vein-portal vein three-dimensional model established using the model 3D from mask tool;
(3) And further extracting a target structure and removing a non-target structure by using MIMICS software, so that only the hepatic vein-portal vein system is reserved, then a hepatic vein-portal vein system solid three-dimensional model with a closed inner cavity is reconstructed, and the hepatic vein-portal vein system solid three-dimensional model is exported.
In some embodiments, the Crop mask tool of the MIMICS software may be utilized to further extract target structures and cull parts of non-target structures (as shown in fig. 8 and 9); and then, removing the residual non-target structures by using an Edit masks in 3D (three-dimensional editing mask) tool of MIMICS software, and only keeping the hepatic vein-portal vein system (as shown in figures 10 and 11).
Optionally, the process of reconstructing the solid three-dimensional model of the endoluminal closing hepatic vein-portal vein system comprises: and selectively filling the hepatic vein-portal vein system and removing noisy pixels by using an Edit mask in 3D (three-dimensional cutting) tool and an Edit mask tool in MIMICS software for multiple times (as shown in figure 12).
In some preferred embodiments, the solid three-dimensional model of the hepatic vein-portal vein system is surface smoothed using Smoothing in MIMICS software prior to outputting the solid three-dimensional model of the hepatic vein-portal vein system. The geometry model data of the smoothed solid three-dimensional model is exported in Ansys area element format (. Inp) as shown in fig. 13 to match the software in S2.
S2, establishing of open model for simulating surgical front door venous pressure
In the SCDM, the three-dimensional model data obtained in S1 is converted and imported into finite element calculation software (such as ANSYS) through boolean operations, and blood flow inlets and outlets of the hepatic vein-portal vein system model are perpendicularly cut, so as to obtain an open model (shown in fig. 14) for simulating the preoperative portal vein pressure.
Preferably, the established open model simulating pre-operative portal vein pressure is derived in IGS format to match S3. Specifically, the IGS is a three-dimensional numerical model file format, and the ANSYS Workbench module is readable.
S3, establishing of an open model simulating portal vein pressure after operation
The IGS format file is imported into ANSYS SCDM for processing, and stents with different diameters and a curvature of 30 degrees are created between the right model hepatic vein and the right model portal vein to simulate the state after the stents with different diameters are placed, so as to obtain an open model simulating the portal vein pressure after the operation (as shown in fig. 15).
In some embodiments, in the ANSYS classic model, a face file (in. Inp) is imported, the length units are unified into international units m, and a solid model body of the hepatic vein-portal vein system (post-operative) model is built on a face basis (as shown in fig. 16).
S4, establishing of mathematical model for simulating portal vein pressure before and after operation
And (4) carrying out finite element mesh division on the model obtained in the S2 and the S3 to obtain a mathematical model for simulating portal vein pressure before and after the operation. An ANSYS Workbench finite element computing platform (as shown in FIG. 17) is established, and comprises a Geometry geometric model module, a Fluent fluid computing module and Results module (namely a CFD-POST POST-processing module) for processing.
Specifically, the models obtained in S2 and S3 are introduced into a Geometry module, an object is divided into introduced numerical models in a Mesh (grid division) unit, a grid division method is set as Tetrahedrons, CFD (computational fluid dynamics analysis) is selected from Physics Preference (physical setting), and Fluent is selected from solution Preference (flow field is solved by Fluent); in consideration of the operation accuracy and the computer running speed, the size of the divided grid is limited, the max face size (maximum face size) is set to be 1.4-1.6 mm, and the max size (maximum size) is set to be 3.8-4.2 mm; after the above setting is completed, the Mesh division is completed by the generation Mesh (generation Mesh).
S5, calculating the blood flow velocity
Substituting the PPG value before the operation into the three-dimensional model before the operation in the fluid mechanics simulation module to calculate and obtain the blood flow velocity of portal vein blood flow entrance so as to simulate the portal vein pressure after different diameter stent operations. The method comprises the steps of setting material parameters, solving control parameters, boundary conditions, portal vein blood flow Reynolds numbers and operation initialization parameters in the solution of a fluid mechanics calculation module Fluent, then calculating the blood flow velocity at the portal vein model blood flow inlet before the operation according to a PPG value before the operation, and obtaining the pressure distribution of a simulated three-dimensional blood vessel model.
Specifically, material parameters (blood density, blood viscosity and blood vessel wall density) are set in the solution of the fluid mechanics calculation module Fluent, so that the physical properties of the model are close to the biological properties of the human body, and the simulation accuracy is improved. Solving control parameters (calculating step length, iteration times and maximum cycle times) and boundary conditions (naming a blood flow inlet surface, giving a speed value, giving a pressure value after naming an outlet surface, and setting an unnamed blood vessel wall as wall), wherein Reynolds number Re of portal blood flow is less than 2000, so that the simulation fluid is set as laminar flow; the operation initialization is set to start from the inlet face (as shown in fig. 18); after the parameter setting is completed, the pressure distribution and the blood flow distribution of the simulated three-dimensional blood vessel model are calculated and obtained (as shown in fig. 19 and 20).
In some embodiments, the blood density may be set to 1030-1060 kg/m 3 The blood viscosity may be set to 0.0035 to 0.005kg/m . s, the time step is 0.01s, and the total time step is 400 steps.
S6, simulating postoperative pressure distribution and portal vein pressure after different-diameter stent operations.
Substituting the blood flow rate obtained in step (5) into the open model of step (3) that simulates the post-operative portal vein pressure, simulating the post-operative pressure distribution and the post-operative portal vein pressure of stents of different diameters, as shown in fig. 21.
Specifically, the method comprises the following steps: and (3) taking the blood flow velocity obtained by calculation in the step (5) as a boundary condition to be brought into the opening model simulating the portal vein pressure after the operation in the step (3), reading the result in a results post-processing module, displaying a liver-portal vein model pressure distribution diagram through contour operation, and calculating to obtain the portal vein pressure gradient after the virtual transjugular intrahepatic portosystemic shunt.
In the actual operation process, the IGS file is imported into ANSYS SCDM, the supports with different diameters and the same curvature (30 degrees) are created between the right hepatic vein support and the right portal vein support, repeated operation is carried out, the pressure distribution of the portal vein model after the simulation operation is obtained, and the pressure reduction effect of the supports with different diameters is verified.
S7, selection of stent diameter
The stent diameter was selected by simulating the portal vein pressure values before and after surgery, as shown in fig. 22.
Specifically, the criteria for selecting the diameter are: post-operative PPG was reduced to 12mmHg or below, and post-operative PPG was reduced by more than 50% from baseline levels.
It needs to be supplemented that TIPS is taken as an effective means for solving various diseases caused by portal hypertension, the diameter of the surgical stent is too small to effectively reduce blood pressure, and the diameter of the surgical stent is too large to easily cause postoperative complications such as hepatic encephalopathy, and the establishment of a safe and accurate stent diameter selection technology becomes an urgent need for research in the field at home and abroad. The invention utilizes the imaging control and modeling software to reconstruct an accurate hepatic vein-portal vein system three-dimensional model of the stents with different diameters, utilizes a finite element computing platform to construct a standardized hydrodynamics simulation analysis process, is expected to provide a new idea for the selection of the diameters of the TIPS operation stents, promotes the improvement of the life quality of patients and reduces the occurrence risk of complications.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
The present embodiment provides a method for selecting a diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent, which adopts the above selection method, and the specific steps refer to fig. 1 to 24 and the above description, which are not repeated herein. The parameters are set as follows:
in the fluid mechanics simulation module Fluent, the material parameters are set: blood density =1050kg/m 3 And blood viscosity =0.005kg/m · s. Solving control parameters ((time step 0.01s, total time steps 400 steps) and boundary conditions ((blood flow velocity, pressure and wall boundary conditions (rigidity) of inlet and outlet), calculating the blood flow velocity at the inlet to be 0.50m/s through analysis and calculation of a post-processing module, simulating blood streamline distribution and pressure distribution before normal model operation (shown in figures 23A and 23C), substituting the simulated velocity at the inlet of the portal vein before operation as the boundary condition into the stent models with different diameters to simulate the blood streamline distribution and pressure distribution after operation (shown in figures 23B and 23D) and PPG value after the stent with different diameters (shown in figure 24).
The pre-operative PPG values for this case were 24mmHg, 8mm stenting, and 10mmHg post-operatively, whereas the simulated post-operative PPG values obtained with 6, 7, 8, 9, 10mm stenting (30 degree flexion) were 13, 11.1, 9.47, 8.08, 6.92mmHg, respectively (as shown in fig. 24). It is recommended to choose a 7mm or 8mm diameter stent.
Comparative example 1
The present comparative example provides a method for selecting a diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent, and the specific steps are described with reference to fig. 1 to 24 and above, which are not repeated herein. In the geometric model module SCDM, the degree of bending of the added stent is set to 0 degree, and in the fluid mechanics simulation module Fluent, the material parameters are set: blood density =1050kg/m 3 Blood viscosity =0.005kg/m · s. Solving control parameters (time step length is 0.01s, total time steps are 400 steps) and boundary conditions (blood flow velocity of inlet and outlet, wall boundary conditions-rigidity), calculating the blood flow velocity of the inlet to be 0.50m/s through analysis and calculation of a post-processing module, substituting the simulated velocity of the portal vein inlet before the operation as the boundary conditions into the stent models with different diameters to simulate the pressure distribution after the operation and PPG values after the stents with different diameters are operated.
The results show that: the pre-operative PPG value for this case was 24mmHg, whereas the simulated post-operative PPG values obtained with the addition of a 6, 7, 8, 9, 10mm stent (degree of flexion 0 degrees) were 12.7, 10.7, 8.9, 7.56, 6.45mmHg, respectively.
Comparative example 2
This comparative example provides a method of selecting a portal hypertension transjugular intrahepatic portosystemic shunt stent diameter, which differs from example 1 only in that the parameter stent bending degree is set to 60 degrees.
The results show that: the post-operative PPG values obtained by adding stents with diameters of 6, 7, 8, 9 and 10mm are respectively 13.26, 11.43, 9.75, 8.38 and 7.26mmHg.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent is characterized by comprising the following steps:
introducing imaging control software to obtain a hepatic vein-portal vein system three-dimensional model by using a CTA hepatic vein phase layer sequence;
converting the obtained three-dimensional model data and importing the three-dimensional model data into finite element calculation software, and making vertical sections on a blood flow inlet and a blood flow outlet of the hepatic vein-portal vein system model to obtain an open model for simulating the portal vein pressure before the operation;
creating stents with different diameters between the right branch of the hepatic vein and the right branch of the portal vein of the model to simulate the state after the stents with different diameters are placed, and obtaining an open model for simulating the portal vein pressure after operation;
carrying out finite element meshing on the opening model of the portal vein pressure before the simulation operation and the opening model of the portal vein pressure after the simulation operation to obtain a mathematical model for simulating the portal vein pressure before and after the simulation operation;
substituting the portal vein pressure gradient value before the operation into the three-dimensional model before the operation in the fluid mechanics simulation module to calculate the blood flow velocity at the portal vein blood flow inlet;
taking the calculated blood flow velocity as a boundary condition to be brought into the opening model simulating the portal vein pressure after the operation, reading the result in a results post-processing module, displaying a liver-portal vein model pressure distribution diagram through contour operation, and calculating to obtain the portal vein pressure value after the virtual transjugular intrahepatic portosystemic shunt;
selecting a bracket with the most suitable diameter by comparing the simulated portal vein pressure gradient values before and after the operation;
wherein the calculating of the blood flow rate comprises: setting material parameters, solving control parameters, boundary conditions, portal vein blood flow Reynolds numbers and operation initialization parameters in the solution of a fluid mechanics calculation module Fluent, then calculating the blood flow velocity at the portal vein model blood flow inlet before the operation according to the portal vein pressure gradient value before the operation and obtaining the pressure distribution of the simulated three-dimensional blood vessel model;
the material parameters include blood density, blood viscosity, and vessel wall density;
solving the control parameters comprises calculating step length, iteration times and maximum cycle times;
the boundary conditions include: naming a blood flow inlet surface and giving a speed value, naming an outlet surface and giving a pressure value, and setting an unnamed blood vessel wall as wall;
the portal blood flow reynolds number is <2000 and the operational initialization is set to start from the entrance face.
2. The method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent according to claim 1, wherein the employed imaging control software is MIMICS software;
the establishment process of the hepatic vein-portal vein system three-dimensional model comprises the following steps: importing the obtained CTA data into MIMICS software, selecting a hepatic vein phase image layer sequence, setting the orientation of the image sequence, and generating images of the coronal position, the sagittal position and the horizontal position of the hepatic vein phase CTA image sequence;
searching in the image by taking a hepatic vein-portal vein system as a target, setting a threshold range by using a threshold tool in MIMICS software to extract the target, and selecting the target by using a Region growing tool in the MIMICS software to extract a structure connected with the target in a spatial structure; establishing a preliminary hepatic vein-portal vein three-dimensional model by using a Call 3D from mask tool in MIMICS software;
extracting a target structure from MIMICS software and removing a non-target structure, so that only a hepatic vein-portal vein system is reserved, then reconstructing a hepatic vein-portal vein system solid three-dimensional model with a closed inner cavity, and exporting the hepatic vein-portal vein system solid three-dimensional model;
selecting an Ansys area element format when the model is exported;
establishing a preliminary hepatic vein-portal vein three-dimensional model by using a calcium 3D from mask tool, and selecting quality as medium;
and before outputting the solid three-dimensional model of the hepatic vein-portal vein system, performing surface Smoothing treatment on the solid three-dimensional model of the hepatic vein-portal vein system by using a smoothening tool in MIMICS software.
3. The method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent according to claim 2, wherein the process of extracting a target structure and rejecting a non-target structure by using MIMICS software comprises: and extracting a target structure by using a Crop mask tool, primarily removing non-target structures, and removing the rest non-target structures by using an Edit mask in 3D tool.
4. The method for selecting a diameter for a portal hypertension transjugular intrahepatic portosystemic shunt stent of claim 2, wherein the process of reconstructing the solid three-dimensional model of the luminal closed hepatic vein-portal vein system comprises: and selectively filling the hepatic vein-portal vein system and removing noisy pixels by using an Edit masks in 3D tool and an Edit masks tool in MIMICS software for many times.
5. The method of selecting a portal hypertension transjugular intrahepatic portosystemic shunt stent diameter according to claim 1, wherein the finite element calculation software is ANSYS;
and (3) exporting the established opening model of the simulated preoperative portal vein pressure in an IGS format, and importing an IGS format file into ANSYS SCDM for processing in step (3).
6. The method for selecting the diameter of a portal hypertension transjugular intrahepatic portosystemic shunt stent according to claim 1, wherein the finite element meshing is performed by sequentially adopting a Geometry geometric model module, a Fluent fluid calculation module and Results module;
introducing the opening model of portal vein pressure before the simulation and the opening model of portal vein pressure after the simulation into a Geometry module, dividing an object in a Mesh unit into introduced numerical models, setting a meshing method as Tetrahedrons, selecting CFD in a Physics Preference, selecting Fluent in a solution Preference, and completing meshing by using a Generator Mesh;
the mesh size is limited, the max face size is set to be 1.4 to 1.6mm, and the max size is set to be 3.8 to 4.2mm.
7. The method of claim 1, wherein the criteria for selecting a suitable diameter is: the gradient value of the postoperative portal vein pressure is reduced to 12mmHg or below, or the gradient value of the postoperative portal vein pressure is reduced by more than 50 percent compared with the baseline level.
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| CN106535773A (en) * | 2014-07-15 | 2017-03-22 | 皇家飞利浦有限公司 | Devices and methods for intrahepatic shunts |
| CN105825070A (en) * | 2016-04-06 | 2016-08-03 | 南方医科大学南方医院 | Measurement method of virtual hepatic vein pressure gradient |
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