CN106473731A - FFR based on personalized coronary arterial tree blood flowCTComputational methods - Google Patents

Abstract

FFR based on personalized coronary arterial tree blood flow_CTComputational methods, belong to biomechanicss and hemodynamics field.First from clinically obtaining the physiological parameters such as myocardial mass, heart rate and the blood pressure of patient, set up the empirical equation of coronary flow calculating based on allometry relative growth rule.The 3-D geometric model of arteria coronaria is gone out based on Coronary Artery in patients CT image reconstruction and obtains blood vessel volume and each branch caliber of coronary branches, be then based on branch vessel volume and Poiseuille law obtains the split ratio of each branch.The split ratio of the coronary flow in conjunction with patient and each branch is calculated the blood flow of each branch of arteria coronaria, and the boundary condition calculating in this, as Coronary hemodynamics is to Coronary Artery in patients FFR_CTSolved.The noinvasive that the present invention is capable of human body arteria coronaria FFR calculates, and personalized coronary flow border can make simulation result be more nearly real blood flow state under Coronary Artery in patients maximum congestive state, thus improving arteria coronaria FFR_CTCalculating accuracy rate.

Description

FFR based on personalized coronary arterial tree blood flowCTComputational methods

Technical field

The present invention relates to biomechanicss, hemodynamics field, more particularly to a kind of Hemodynamics Numerical Simulation skill Art, can be used for the personalized boundary condition setting of human coronaries' hemodynamics simulation calculation, and then realizes FFR_CTNumber Value simulation calculates.

Background technology

Arteria coronaria FFR technology is clinically to be used at present diagnosing whether coronary stenosis cause downstream myocardial ischemia " gold mark Accurate ", but because it is invasive, somewhat expensive the problems such as, clinical practice is very limited, and then expedites the emergence of out arteria coronaria FFR_CTSkill Art.Arteria coronaria FFR_CTTechnology is based on Coronary Artery in patients CT image, realizes the hemodynamics emulation of arteria coronaria using method for numerical simulation, By extracting, narrow arteria coronaria upstream and downstream pressure value is noninvasive to obtain its FFR value, i.e. FFR_CTValue.In FFR_CTIn technology, arteria coronaria three Quality that dimension module is rebuild and the setting of hydrodynamics method boundary condition be impact two of result of calculation accuracy main because Element.This research emphasis pays close attention to the latter.

In pressure flow boundary condition, the accuracy of arteria coronaria each rate of discharge setting will directly influence FFR_CTMeter Calculate the accuracy of result.The determination of rate of discharge relies primarily on two aspects：One is the calculating of coronary flow；Two is each point of arteria coronaria The assignment of traffic propped up.Hereinafter two aspects are illustrated respectively.

With regard to coronary flow, mainly there are two kinds of evaluation methods at present.One is to account for cardiac output according to coronary flow 4%～5% estimated.This method is the simplest, directly, but error is also maximum, to cardiac insufficiency, Left Ventricular Global Dysfunction Patient easily causes and underestimates.Two is according to the power law relation that myocardial mass has 0.75 with coronary flow, coronary flow to be entered Row estimation.The method estimates coronary flow from myocardial demand angle, has been improved with respect to first method accuracy.But On the one hand myocardial mass is only, and different patients also have the difference of perfusion level, and therefore single myocardial mass factor is difficult to Realize the estimation of personalized coronary flow.

With regard to the assignment of traffic of each branch of arteria coronaria, two kinds of main stream approach are respectively Blood flow distribution and base based on length of vessel Blood flow distribution in blood vessels caliber.From the theoretical consideration of structure-function relationship, length of vessel and blood vessels caliber all can be to flows Distribution produces certain impact.Equal length may be neglected based on the Blood flow distribution method of branch vessel length but caliber is different Vascular shunt amount difference, and the classification in Calibration position, branch vessel for the Blood flow distribution method based on blood vessels caliber The problems such as on more complicated it is difficult to regularization.Therefore, individually consider that any of which factor is all possible to bring error.

Content of the invention

The invention mainly solves the technical problem of providing a kind of FFR based on personalized coronary arterial tree blood flow_CT Computational methods, can provide for the dynamic (dynamical) numerical simulation of human body coronary flow that one kind is easier, direct boundary condition Method to set up, and its accuracy can be ensured to a certain extent.

For solving above-mentioned technical problem, one aspect of the present invention is：A kind of personalized determination patient is provided The method of coronary flow, and set up the empirical equation that under patient's maximum congestive state, coronary flow calculates.Propose one simultaneously Plant the flow allocation method based on coronary branches blood vessel volume, joint Poiseuille law can get the blood of each branch outlet of arteria coronaria Flow.Numerical simulation is carried out as the boundary condition calculating to Coronary Artery in patients blood flow using the blood flow of each outlet of arteria coronaria, by right The post processing noninvasive acquisition arteria coronaria FFR of result_CTValue.

Described personalization, is to consider the life that patient individual is different from other patients on the basis of universality rule Manage bar part, including myocardial mass, heart rate, blood pressure, makes physiological parameter of interest closer to the actual value of patient.

Described coronary arterial tree blood vessel volume, including left anterior descending branch coronarius（LAD）, left Circumflex branch（LCX） And right coronary artery（RCA）Three big branches.

Described coronary flow, for full coronary flow, is different from the blood flow of localized branches arteria coronaria.

Described maximum congestive state, after being the vasodilation medicines such as patient's injection adenosine, makes Coronary microcirculation resistance drop To minimum, during the maximum groundwater increment of arteria coronaria acquisition state.

Determine comprising the following steps that of arteria coronaria each branch blood flow.

Step one, the empirical equation that under maximum congestive state, coronary flow calculates.This formula has accounted for patient's heart Myoplasm amount, heart rate and diastolic pressure, are carried out to patient's coronary artery blood flow calculating solution in the form of mathematic(al) representation, specifically ask Solution preocess is as follows.

M in above formula_myoFor the full myocardial mass of patient, that is, comprise left and right room myocardial mass and other myocardial cell quality； HR is Heart Rate,Heart rate average for healthy population；DP is patient's diastolic pressure,Equal for the diastolic pressure of healthy population Value；α is a constant value.

This method passes through Left ventricular myocardial mass（M_L）Accounting relation and full myocardial mass between, using Left ventricular myocardial mass Full myocardial mass is calculated.Relevant clinical research shows, Left ventricular myocardial mass accounts for the 75% of full myocardial mass.Medical science is united Meter analysis obtains the heart rate of healthy population and diastolic pressure average be respectively 75 times/min, 85mmHg.Meanwhile, maximum congestive state Under, the average level of human body myocardial flow is 3.3～3.5mL/min/g.Then have

Step 2, the flow allocation method based on coronary branches blood vessel volume.The measurement big arteria coronaria of LAD, LCX and RCA tri- divides The blood vessel volume propped up, obtains the distribution ratio of liquid flow of coronary branches according to the rule between local coronary blood pipe volume and blood flow, Specific derivation process is as follows

Research shows, patient's local myocardial quality is directly proportional with corresponding local coronary blood pipe volume, corresponds to arteria coronaria Three big branches are

M_LAD=kV_{vessel LAD}；M_LCX=kV_{vessel LCX}；M_RCA=kV_{vessel RCA}

Wherein M_LAD、M_LCX、M_RCAIt is respectively the myocardial mass of LAD, LCX, RCA corresponding region；V_{vessel LAD}、V_{vessel LCX}、 V_{vessel RCA}It is respectively the blood vessel volume of LAD, LCX, RCA；K is a proportionality constant.

Meanwhile, there is 0.75 power law relation between local myocardial volume and the coronary flow of corresponding region, that is, have

Q_LAD=lM_LAD ^0.75；Q_LCX=lM_LCX ^0.75；Q_RCA=lM_RCA ^0.75

Wherein Q_LAD、Q_LCX、Q_RCAIt is respectively the blood flow of LAD, LCX, RCA；L is a proportionality constant.

By above two formulas, following formula can be derived from

Q_LAD=lkV_{vessel LAD} ^0.75；Q_LCX=lkV_{vessel LCX} ^0.75；Q_RCA=lkV_{vessel RCA} ^0.75

There is 0.75 power law relation between local coronary flow and corresponding coronary blood pipe volume.

Thus, the split ratio that can draw the big coronary branches of LAD, LCX, RCA tri- is

Q_LAD:Q_LCX:Q_RCA=V_{vessel LAD} ^0.75:V_{vessel LCX} ^0.75:V_{vessel RCA} ^0.75

Step 3, the determination of the blood flow of three big coronary branches.

Full coronary flow is LAD, LCX, RCA branch blood flow sum, that is,

Q_cor=Q_LAD+Q_LCX+Q_RCA

Then LAD, LCX, RCA branch blood flow is respectively

Step 4, the determination of arteria coronaria each branch outlet flow.

From Poiseuille law and blood vessel energy dissipation theory, ideally, an endovascular flow and blood vessel 3 powers of caliber are directly proportional, that is,

Wherein, Q is intravascular flow, and d is blood vessel diameter, and μ is hemodynamicses viscosity coefficient, and λ is a proportionality constant, represents The energy that vascular units volume metabolism is consumed.

If it is a that LAD respectively exports caliber₁,a₂,......,a_n, it is b that LCX respectively exports caliber₁,b₂,......,b_m, RCA respectively goes out Mouth caliber is c₁,c₂,......,c_s, then each rate of discharge of LAD, LCX and RCA be

Arteria coronaria each exit blood flow amount that aforesaid way is determined, as boundary condition, is applied to and is rebuild based on CT picture of patient Arteria coronaria threedimensional model in carry out hemodynamics simulation calculation, extract narrow arteria coronaria upstream and downstream blood from fluid calculation result Pressure（P_aAnd P_d）, using formulaArteria coronaria FFR is tried to achieve in calculating_CTValue.

The invention has the beneficial effects as follows：The noinvasive that the present invention is capable of human body arteria coronaria FFR calculates, the arteria coronaria stream of personalization Amount border can make simulation result be more nearly real blood flow state under Coronary Artery in patients maximum congestive state, thus improving arteria coronaria FFR_CTCalculating accuracy rate.

Brief description

Fig. 1 is human coronaries' three dimensional structure diagram；

Fig. 2 is the schematic flow sheet of the present invention；

Specific embodiment

Referring to the schematic flow sheet of the present invention, one embodiment of the present of invention is described in detail, so that this Bright advantages and features can be easier to be readily appreciated by one skilled in the art, thus make apparent to protection scope of the present invention Clearly define.

Step one, the clinical physiological parameter such as the heart rate of collection patient, diastolic pressure and myocardial mass.

Step 2, based on the 0.75 of coronary flow and myocardial mass power law relation, include heart rate, diastolic pressure because Element, sets up the empirical equation of coronary flow calculating,

Step 3, substitutes into 75 times/min of heart rate average, diastolic pressure average 85mmHg, Left ventricular myocardial mass, and with human body Under big congestive state, heart muscle perfusion average level 3.3～3.5mL/min/g is calculated corrected parameter α=12, and then draws maximum Under congestive state, the empirical equation of coronary flow calculating is

Step 4, is analysed to the physiological parameters such as myocardial mass, heart rate and the diastolic pressure of patient and is updated to maximum hyperemia shape The coronary flow of this patient is calculated in the empirical equation that under state, coronary flow calculates.

Step 5, goes out arteria coronaria threedimensional model based on this Coronary Artery in patients CT image reconstruction, and model is carried out with the pre- place such as smooth Reason.

Step 6, the volume of measurement big branch vessel LAD, LCX of arteria coronaria three and RCA.

Step 7, obtains the split ratio of three big branches based on branch vessel volume.

M_LAD=kV_{vessel LAD}；M_LCX=kV_{vessel LCX}；M_RCA=kV_{vessel RCA}

Q_LAD=lM_LAD ^0.75；Q_LCX=lM_LCX ^0.75；Q_RCA=lM_RCA ^0.75

Then have

Q_LAD=lkV_{vessel LAD} ^0.75；Q_LCX=lkV_{vessel LCX} ^0.75；Q_RCA=lkV_{vessel RCA} ^0.75

Q_LAD:Q_LCX:Q_RCA=V_{vessel LAD} ^0.75:V_{vessel LCX} ^0.75:V_{vessel RCA} ^0.75

Step 8, in conjunction with coronary flow and three big thus bypasses ratios, obtains the blood flow of the big branch of arteria coronaria three.

Step 9, joint Poiseuille law, obtain the blood flow of each branch outlet of arteria coronaria.

Step 10, the boundary condition that each for arteria coronaria rate of discharge is calculated as hemodynamics, simultaneously aortic root enter Mouth applies cardiac output, outlet applies mean arterial pressure, carries out hemodynamics simulation calculation.

Step 11, the post processing of simulation result, extract narrow arteria coronaria upstream and downstream blood pressure（P_aAnd P_d）, using formulaArteria coronaria FFR is tried to achieve in calculating_CTValue.

According to above method step, complete the FFR of 8 patients totally 10 narrow arteria coronaria_CTCalculate, now simulation calculation is tied Fruit is collected in Table 1 with the contrast of clinical actual measurement FFR value.

Table 1 arteria coronaria FFR_CTContrast with clinical actual measurement FFR collects

From table 1, data can be seen that, the FFR being obtained using the method simulation calculation_CTCarry out myocardial ischemia judgement（FFR_CT ≤0.8）Result basically identical with clinical actual measurement FFR.

The foregoing is only embodiments of the invention, not thereby limit the present invention the scope of the claims, every using this Equivalent structure or equivalent flow conversion that bright description and accompanying drawing content are made, or directly or indirectly it is used in other related skills Art field, is included within the scope of the present invention.

Claims (1)

1. a kind of FFR based on personalized coronary arterial tree blood flow_CTComputational methods, coronary arterial tree blood vessel volume, bag Include left anterior descending branch LAD coronarius, left Circumflex branch LCX and the big branch of right coronary artery RCA tri-；

It is characterized in that step is as follows：

Step one, the empirical equation that under maximum congestive state, coronary flow calculates.

$Q_{cor}=\mathrm{\α}\left(\frac{\stackrel{\‾}{HR}}{HR}\right)\left(\frac{DP}{\stackrel{\‾}{DP}}\right){M_{myo}}^{0.75}$

M in above formula_myoFor the full myocardial mass of patient, that is, comprise left and right room myocardial mass and other myocardial cell quality；HR is Heart Rate,Heart rate average for healthy population；DP is patient's diastolic pressure,Diastolic pressure average for healthy population；α is One constant value.

Relevant clinical research shows, Left ventricular myocardial mass M_LAccount for the 75% of full myocardial mass.Medical statistical analysis obtains Healthy People Group heart rate and diastolic pressure average be respectively 75 times/min, 85mmHg.Meanwhile, under maximum congestive state, human body myocardial flow Average level be 3.3～3.5mL/min/g.Then have

$Q_{cor}=12\left(\frac{75}{HR}\right)\left(\frac{DP}{85}\right){\left(\frac{M_L}{0.75}\right)}^{0.75}$

Step 2, the flow allocation method based on coronary branches blood vessel volume.Research shows, patient's local myocardial quality with relative The local coronary blood pipe volume answered is directly proportional, and corresponds to the big branch of arteria coronaria three and is

M_LAD=kV_{vessel LAD}；M_LCX=kV_vesselLCX；M_RCA=kV_vesselRCA

Wherein M_LAD、M_LCX、M_RCAIt is respectively the myocardial mass of LAD, LCX, RCA corresponding region；V_{vessel LAD}、V_{vessel LCX}、 V_{vessel RCA}It is respectively the blood vessel volume of LAD, LCX, RCA；K is a proportionality constant.

Meanwhile, there is 0.75 power law relation between local myocardial volume and the coronary flow of corresponding region, that is, have Q_LAD= lM_LAD ^0.75；Q_LCX=lM_LCX ^0.75；Q_RCA=lM_RCA ^0.75

Wherein Q_LAD、Q_LCX、Q_RCAIt is respectively the blood flow of LAD, LCX, RCA；L is a proportionality constant.

By above two formulas, it is derived from following formula

Q_LAD=lkV_{vessel LAD} ^0.75；Q_LCX=lkV_vesselLCX ^0.75；Q_RCA=lkV_{vessel RCA} ^0.75

There is 0.75 power law relation between local coronary flow and corresponding coronary blood pipe volume.

The split ratio drawing the big coronary branches of LAD, LCX, RCA tri- is

Q_LAD:Q_LCX:Q_RCA=V_{vessel LAD} ^0.75:V_{vessel LCX} ^0.75:V_{vessel RCA} ^0.75

Step 3, the determination of the blood flow of three big coronary branches.

Full coronary flow is LAD, LCX, RCA branch blood flow sum, that is,

Q_cor=Q_LAD+Q_LCX+Q_RCA

Then LAD, LCX, RCA branch blood flow is respectively

$Q_{LAD}=\frac{{V_{vesselLAD}}^{0.75}}{{V_{vesselLAD}}^{0.75}+{V_{vesselLCX}}^{0.75}+{V_{vesselRCA}}^{0.75}}{Q}_{cor}$

$Q_{LCX}=\frac{{V_{vesselLCX}}^{0.75}}{{V_{vesselLAD}}^{0.75}+{V_{vesselLCX}}^{0.75}+{V_{vesselRCA}}^{0.75}}{Q}_{cor}$

$Q_{RCA}=\frac{{V_{vesselRCA}}^{0.75}}{{V_{vesselLAD}}^{0.75}+{V_{vesselLCX}}^{0.75}+{V_{vesselRCA}}^{0.75}}{Q}_{cor}$

Step 4, the determination of arteria coronaria each branch outlet flow.

From Poiseuille law and blood vessel energy dissipation theory, ideally, an endovascular flow and blood vessels caliber 3 powers be directly proportional, that is,

$Q=\frac{{\mathrm{\πd}}^3}{4}\sqrt{\frac{\mathrm{\λ}}{\mathrm{\μ}}}$

Wherein, Q is intravascular flow, and d is blood vessel diameter, and μ is hemodynamicses viscosity coefficient, and λ is a proportionality constant, represents blood vessel The energy that unit volume metabolism is consumed.

If it is a that LAD respectively exports caliber₁,a₂,......,a_n, it is b that LCX respectively exports caliber₁,b₂,......,b_m, each outlet of RCA Footpath is c₁,c₂,......,c_s, then each rate of discharge of LAD, LCX and RCA be

$Q_{LAD-j}=Q_{LAD}\frac{{a_j}^3}{\underset{i=1}{\overset{n}{\Σ}}{a_i}^3}$

$Q_{LCX-j}=Q_{LCX}\frac{{b_j}^3}{\underset{i=1}{\overset{m}{\Σ}}{b_i}^3}$

$Q_{RCA-j}=Q_{RCA}\frac{{c_j}^3}{\underset{i=1}{\overset{s}{\Σ}}{c_i}^3}$

Using the blood flow of each outlet of arteria coronaria as the boundary condition calculating to Coronary Artery in patients FFR_CTSolved.Based on Coronary Artery in patients CT image reconstruction goes out arteria coronaria threedimensional model, using each for arteria coronaria rate of discharge as boundary condition, carries out blood flow to arteria coronaria threedimensional model Dynamics simulation, by extracting narrow arteria coronaria upstream blood pressure P to result post processing_aWith downstream blood pressure P_d, using formulaArteria coronaria FFR is tried to achieve in calculating_CTValue.