Method for evaluating lower limb artery stenosis degree

Abstract

The invention discloses a method for evaluating the stenosis degree of lower limb arteries, which comprises the following steps: S1, acquiring clinical data, including a DSA image of the lower limb arteries, brachial artery blood pressure, blood routine, and a CTA image or MRA image of the lower limb arteries; s2, establishing a geometric model, and establishing a narrow artery three-dimensional model and a non-narrow artery three-dimensional model; s3, calculating the blood flow of each outlet of the narrow lower limb artery and the resistance value of each outlet of the lower limb artery; s4, calculating the blood flow of each outlet of the non-narrow lower limb artery; s5, the fractional flow reserve of each outlet of the lower limb artery is calculated, and the stenosis degree of the lower limb artery is evaluated. Definition of the fractional flow reserve of the lower limb artery is introduced, and the stenosis degree of the lower limb artery is evaluated according to the ratio of the blood supply condition of the stenosis lower limb artery to the healthy blood supply condition.

Description

Technical Field

[0001] The invention relates to the field of medical technology, and in particular to a method for evaluating the degree of lower limb artery stenosis. Background Art

[0002] Lower extremity arterial stenosis is the main cause of lower extremity arterial disease. An epidemiological survey of 56,000 people aged ≥35 years found that the prevalence of lower extremity arterial stenosis in this population was 6.6%, of which only 4.9% were aware of their condition. Severe lower extremity arterial stenosis may lead to serious consequences such as claudication and lower extremity necrosis. Therefore, it is of great clinical value to accurately assess the degree of lower extremity arterial stenosis and develop patient-specific surgical plans.

[0003] Currently, the degree of lower limb artery stenosis is assessed clinically based on CTA images. However, this can only reflect the geometric degree of stenosis in the lower limb arteries and cannot directly reflect the impact of stenosis on the blood supply capacity of the lower limb arteries.

[0004] Patent application CN116458867A proposes a method for indirectly evaluating the health status of lower limb arteries based on the impedance volume waves of the user's legs. The problem with this method is that it cannot accurately reflect the degree of functional stenosis of the lower limb arteries and cannot achieve clinical surgical planning for lower limb artery stenosis.

[0005] Patent application CN114259256A proposes a method for measuring blood pressure in lower limb arteries and evaluating the stenosis of lower limb arteries. The problem with this method is that it cannot directly reflect the blood flow in the lower limb arteries, and it is also difficult to evaluate the effect of the surgical plan before surgery. Therefore, clinical surgical planning for lower limb artery stenosis cannot be achieved.

[0006] Currently, there is a lack of methods and indicators to evaluate the degree of functional stenosis of lower extremity arteries. Therefore, it is difficult to accurately plan surgical plans from a hemodynamic perspective.

[0007] Therefore, those skilled in the art are committed to developing a method for evaluating the degree of functional stenosis of lower extremity arteries.

[0008] In order to accurately assess the degree of lower extremity arterial stenosis and develop patient-specific surgical plans, the present invention will introduce the definition of lower extremity arterial blood flow reserve fraction for the first time, creating a new method. That is, based on clinical data such as arterial CTA images (or MRA images), DSA images, brachial artery blood pressure, and blood routine tests, the ratio of blood flow after lower extremity arterial stenosis to blood flow in a healthy state is obtained non-invasively, thereby assessing the degree of loss of lower extremity arterial blood supply capacity caused by stenosis. Summary of the invention

[0009] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is the lack of methods and indicators for evaluating the degree of functional stenosis of lower limb arteries, making it difficult to accurately plan surgical plans from a hemodynamic perspective.

[0010] In a first aspect, the present invention provides a method for evaluating the degree of lower extremity arterial stenosis, comprising:

[0011] Step S1: Obtain clinical data,

[0012] The clinical data include DSA images of lower limb arteries, brachial artery blood pressure, blood routine, CTA images or MRA images of lower limb arteries;

[0013] Step S2: Establishing geometric model,

[0014] A three-dimensional model of a stenotic artery is established, which is recorded as model A, and a three-dimensional model of a non-stenotic artery is established, which is recorded as model B;

[0015] Step S3: Calculate the blood flow A at each outlet of the lower limb artery of model A i , i = 1...N, N is the number of lower limb artery outlets, calculate the resistance value R of each lower limb artery outlet i , i=1…N;

[0016] Step S4: Calculate the numerical model of model B to obtain the blood flow B at each outlet of the lower limb artery of model B i , i=1…N;

[0017] Step S5: Calculate the blood flow reserve fraction of each outlet of the lower limb artery to assess the degree of lower limb artery stenosis.

[0018] Calculate the blood flow reserve fraction E at each outlet of the lower limb artery i , E i =A i / B i , i=1…N,

[0019] When the blood flow reserve fraction E of any outlet i When the value is ≤ the threshold, the degree of lower limb artery stenosis is assessed as high, otherwise it is assessed as low.

[0020] Further, step S2 may be specifically configured as follows:

[0021] The CTA image or MRA image of the lower limb artery is imported into SimVascular software to establish a three-dimensional model of the stenotic artery, which is recorded as model A. Model A is imported into SimVascular software to establish a three-dimensional model of the artery without stenosis, which is recorded as model B.

[0022] Further, in step S3, the blood flow A of each outlet of the lower limb artery of model Ai The method for obtaining can be based on DSA images.

[0023] Further, the resistance value R of each outlet of the lower limb artery in step S3 i The method of obtaining can be specifically as follows:

[0024] In the OpenFoam software, the blood flow A of each outlet of the lower limb artery of model A is i As the boundary condition of the outlet, the brachial artery blood pressure is used as the inlet boundary condition. It is assumed that the blood is an incompressible Newtonian fluid. The viscosity and density of the blood are derived from the blood routine data.

[0025] Divide the mesh of model A and determine the calculation domain.

[0026] The NS equation is solved by the steady-state numerical simulation method to obtain the blood pressure P at each outlet of the lower limb artery. i , i=1…N,

[0027] Calculate the resistance value R of each outlet of the lower limb artery i =P i / A i , i=1…N.

[0028] Further, step S4 may specifically be:

[0029] In the OpenFoam software, the resistance value R of each outlet of the lower limb artery is i As the boundary condition of the outlet, the brachial artery blood pressure is used as the inlet boundary condition. It is assumed that the blood is an incompressible Newtonian fluid. The viscosity and density of the blood are derived from the blood routine data.

[0030] Divide the mesh of model B and determine the calculation domain.

[0031] The NS equations were solved by the steady-state numerical simulation method to obtain the blood flow B at each outlet of the lower limb artery of model B. i , i=1…N.

[0032] Further, the threshold value range in step S5 may be: 0.6≤threshold≤0.9.

[0033] Furthermore, threshold = 0.8.

[0034] In a second aspect, the present invention provides a method for assisting lower limb artery stenosis surgery planning based on the method described in the first aspect, comprising:

[0035] Step 1: Preoperative assessment,

[0036] Use steps S1-S5 to evaluate the degree of lower extremity artery stenosis. If the degree of lower extremity artery stenosis is high, proceed to step 2: surgical planning. Otherwise, step 2: surgical planning is not required.

[0037] Step 2: Surgical planning,

[0038] When there is only one outlet, the blood flow reserve fraction E i When the value is less than or equal to the threshold, a simulated operation is performed on the stenotic artery based on SimVascular software or a finite element simulated operation is performed to obtain a model after the simulated operation. The model after the simulated operation is used as model A, and steps S1-S5 are used to evaluate the degree of lower limb artery stenosis after the simulated operation. If the degree of lower limb artery stenosis after the simulated operation is low, it meets the clinical needs. Otherwise, the surgical plan is modified.

[0039] When there are 2 or more outlets, the blood flow reserve fraction E i When the value is less than or equal to the threshold, a single site of the stenotic artery is subjected to a simulated surgery based on SimVascular or finite element simulation to obtain a model after the simulated surgery, and the model after the simulated surgery is used in steps S1-S5 to obtain the blood flow reserve scores of each outlet after the simulated surgery, so as to evaluate which part of the simulated surgery can achieve a better effect;

[0040] Step 3: Postoperative evaluation,

[0041] Steps S1-S5 were used to evaluate the degree of lower extremity artery stenosis after surgery and to assess the postoperative effect.

[0042] In a third aspect, the present invention provides a computer device, comprising:

[0043] Memory;

[0044] One or more processors coupled to the memory;

[0045] One or more applications, wherein the one or more applications are stored in the memory and configured to be executed by one or more processors, and the one or more applications are configured to execute the method for assessing the degree of lower extremity artery stenosis according to the first aspect.

[0046] In a fourth aspect, the present invention provides a computer-readable storage medium having program code stored therein, and the program code can be called by a processor to execute the method for assessing the degree of lower extremity artery stenosis described in the first aspect.

[0047] Technical effect:

[0048] The present invention introduces the definition of lower extremity artery blood flow reserve fraction, creating a new method. Starting from the definition of blood flow reserve fraction, the degree of lower extremity artery stenosis is assessed by the ratio of the blood supply status of the lower extremity artery after stenosis to the blood supply status when healthy. This method can be used to accurately assess the degree of lower extremity artery stenosis and formulate patient-specific surgical plans, thereby reducing medical costs and reducing the burden on national medical insurance.

[0049] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a flowchart of a method for evaluating the degree of lower extremity arterial stenosis according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0051] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0052] In the drawings, components with the same structure are denoted by the same numerical numerals, and components with similar structure or function are denoted by similar numerical numerals.

[0053] like Figure 1 As shown, the first embodiment of the present invention provides a method for evaluating the degree of lower extremity arterial stenosis, comprising:

[0054] Step S1: Obtain clinical data,

[0055] The clinical data include DSA images of lower limb arteries, brachial artery blood pressure, blood routine, CTA images or MRA images of lower limb arteries;

[0056] Step S2: Establishing geometric model,

[0057] Importing the CTA image or MRA image of the lower limb artery into SimVascular software to establish a three-dimensional model of the stenotic artery, which is recorded as model A; importing model A into SimVascular software to establish a three-dimensional model of the artery without stenosis, which is recorded as model B;

[0058] Step S3: Calculate the blood flow and resistance values ​​of each outlet of the lower limb artery of model A.

[0059] The blood flow A of each outlet of the lower limb artery of model A was obtained based on DSA images i , i = 1...N, N is the number of lower limb arterial outlets,

[0060] For exit i, the number of frames in which the contrast agent reaches observation point 1 is K S , the number of frames when the contrast agent reaches observation point 2 is set to K E , the distance between the two observation points is L, the number of contrast frames per second is N, and the flow velocity at outlet i is V i It is expressed as:

[0061] V i =L×N / (K E -K S )

[0062] The blood vessel area is S i , the flow rate A at exit i i It is expressed as:

[0063] A i =S i ×V i

[0064] In the OpenFoam software, the blood flow A of each outlet of the lower limb artery of model A is i As the boundary condition of the outlet, the brachial artery blood pressure is used as the inlet boundary condition. It is assumed that the blood is an incompressible Newtonian fluid. The viscosity and density of the blood are derived from the blood routine data.

[0065] Divide the mesh of model A and determine the calculation domain.

[0066] The NS equation is solved by the steady-state numerical simulation method to obtain the blood pressure P at each outlet of the lower limb artery. i , i=1…N,

[0067] Calculate the resistance value R of each outlet of the lower limb artery i =P i / A i , i=1…N;

[0068] Step S4: Calculate the numerical model of model B,

[0069] In the OpenFoam software, the resistance value R of each outlet of the lower limb artery is i As the boundary condition of the outlet, the brachial artery blood pressure is used as the inlet boundary condition. It is assumed that the blood is an incompressible Newtonian fluid. The viscosity and density of the blood are derived from the blood routine data.

[0070] Divide the mesh of model B and determine the calculation domain.

[0071] The NS equations were solved by the steady-state numerical simulation method to obtain the blood flow B at each outlet of the lower limb artery of model B. i , i=1…N;

[0072] Step S5: Calculate the blood flow reserve fraction of each outlet of the lower limb artery to assess the degree of lower limb artery stenosis.

[0073] Calculate the blood flow reserve fraction E at each outlet of the lower limb artery i , E i =A i / B i , i=1…N,

[0074] When the blood flow reserve fraction E of any outlet i When the stenosis level of lower extremity arteries is less than or equal to the threshold, the stenosis level is assessed as high; otherwise, it is assessed as low.

[0075] The threshold value range can be: 0.6≤threshold≤0.9,

[0076] Preferably, threshold = 0.8.

[0077] The second embodiment of the present invention provides a method for assisting lower limb artery stenosis surgery planning based on the method described in the first embodiment, comprising:

[0078] Step 1: Preoperative assessment,

[0079] Use steps S1-S5 to evaluate the degree of lower extremity artery stenosis. If the degree of lower extremity artery stenosis is high, proceed to step 2: surgical planning. Otherwise, step 2: surgical planning is not required.

[0080] Step 2: Surgical planning,

[0081] When there is only one outlet, the blood flow reserve fraction E i When the value is less than or equal to the threshold, a simulated operation is performed on the stenotic artery based on SimVascular software or a finite element simulated operation is performed to obtain a model after the simulated operation. The model after the simulated operation is used as model A, and steps S1-S5 are used to evaluate the degree of lower limb artery stenosis after the simulated operation. If the degree of lower limb artery stenosis after the simulated operation is low, it meets the clinical needs. Otherwise, the surgical plan is modified.

[0082] When there are 2 or more outlets, the blood flow reserve fraction E i When the value is less than or equal to the threshold, a single site of the stenotic artery is subjected to a simulated surgery based on SimVascular or finite element simulation to obtain a model after the simulated surgery, and the model after the simulated surgery is used in steps S1-S5 to obtain the blood flow reserve scores of each outlet after the simulated surgery, so as to evaluate which part of the simulated surgery can achieve a better effect;

[0083] Step 3: Postoperative evaluation,

[0084] Steps S1-S5 were used to evaluate the degree of lower extremity artery stenosis after surgery and to assess the postoperative effect.

[0085] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for evaluating the degree of lower extremity arterial stenosis, characterized in that: include, Step S1: Obtain clinical data, The clinical data include DSA images of lower limb arteries, brachial artery blood pressure, blood routine, CTA images or MRA images of lower limb arteries; Step S2: Establishing geometric model, A three-dimensional model of the narrowed artery is established, denoted as model A. A three-dimensional model of an artery without stenosis was established, which was recorded as model B; Step S3: Calculate the blood flow A at each outlet of the lower limb artery of model A i , i = 1...N, N is the number of lower limb artery outlets, calculate the resistance value R of each lower limb artery outlet i , i=1…N; Step S4: Calculate the numerical model of model B to obtain the blood flow B at each outlet of the lower limb artery of model B i , i=1…N; Step S5: Calculate the blood flow reserve fraction of each outlet of the lower limb artery to assess the degree of lower limb artery stenosis. Calculate the blood flow reserve fraction E at each outlet of the lower limb artery i , E i =A i / B i , i=1…N, When the blood flow reserve fraction E of any outlet i When the value is ≤ the threshold, the degree of lower limb artery stenosis is assessed as high, otherwise it is assessed as low.

2. The method for evaluating the degree of lower extremity arterial stenosis according to claim 1, characterized in that: Step S2 is: The CTA image or MRA image of the lower limb artery is imported into SimVascular software to establish a three-dimensional model of the stenotic artery, which is recorded as model A. Model A is imported into SimVascular software to establish a three-dimensional model of the artery without stenosis, which is recorded as model B.

3. The method for evaluating the degree of lower extremity arterial stenosis according to claim 1, characterized in that: The blood flow A of each outlet of the lower limb artery of model A in step S3 i The method for obtaining is based on DSA images.

4. The method for evaluating the degree of lower extremity arterial stenosis according to claim 1, characterized in that: The resistance value R of each outlet of the lower limb artery in step S3 i The method to obtain is: In the OpenFoam software, the blood flow A of each outlet of the lower limb artery of model A is i As the boundary condition of the outlet, the brachial artery blood pressure is used as the inlet boundary condition. It is assumed that the blood is an incompressible Newtonian fluid. The viscosity and density of the blood are derived from the blood routine data. Divide the mesh of model A and determine the calculation domain. The NS equation is solved by the steady-state numerical simulation method to obtain the blood pressure P at each outlet of the lower limb artery. i , i=1…N, Calculate the resistance value R of each outlet of the lower limb artery i =P i / A i , i=1…N.

5. The method for evaluating the degree of lower extremity arterial stenosis according to claim 1, characterized in that: Step S4 is: In the OpenFoam software, the resistance value R of each outlet of the lower limb artery is i As the boundary condition of the outlet, the brachial artery blood pressure is used as the inlet boundary condition. It is assumed that the blood is an incompressible Newtonian fluid. The viscosity and density of the blood are derived from the blood routine data. Divide the mesh of model B and determine the calculation domain. The NS equations were solved by the steady-state numerical simulation method to obtain the blood flow B at each outlet of the lower limb artery of model B. i , i=1…N.

6. The method for evaluating the degree of lower extremity arterial stenosis according to claim 1, characterized in that: 0.6≤Threshold≤0.

9.

7. The method for evaluating the degree of lower extremity arterial stenosis according to claim 6, characterized in that: Threshold = 0.

8.

8. A method for assisting lower limb artery stenosis surgery planning based on any one of claims 1 to 7, characterized in that: include, Step 1: Preoperative assessment, Use steps S1-S5 to evaluate the degree of lower extremity artery stenosis. If the degree of lower extremity artery stenosis is high, proceed to step 2: surgical planning. Otherwise, step 2: surgical planning is not required. Step 2: Surgical planning, When there is only one outlet, the blood flow reserve fraction E i When the value is less than or equal to the threshold, a simulated operation is performed on the stenotic artery based on SimVascular software or a finite element simulated operation is performed to obtain a model after the simulated operation. The model after the simulated operation is used as model A, and steps S1-S5 are used to evaluate the degree of lower limb artery stenosis after the simulated operation. If the degree of lower limb artery stenosis after the simulated operation is low, it meets the clinical needs. Otherwise, the surgical plan is modified. When there are 2 or more outlets, the blood flow reserve fraction E i When the value is less than or equal to the threshold, a single site of the stenotic artery is subjected to a simulated surgery based on SimVascular or finite element simulation to obtain a model after the simulated surgery, and the model after the simulated surgery is used in steps S1-S5 to obtain the blood flow reserve scores of each outlet after the simulated surgery, so as to evaluate which part of the simulated surgery can achieve a better effect; Step 3: Postoperative evaluation, Steps S1-S5 were used to evaluate the degree of lower extremity artery stenosis after surgery and to assess the postoperative effect.

9. A computer device, characterized in that: include: Memory; One or more processors coupled to the memory; One or more applications, wherein the one or more applications are stored in the memory and are configured to be executed by one or more processors, and the one or more applications are configured to execute the method for assessing the degree of lower extremity artery stenosis as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program codes, which can be called by a processor to execute the method for assessing the degree of lower extremity artery stenosis as described in any one of claims 1-7.

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