WO2020215442A2 - 一种通过常规造影图像测量出血流储备分数的方法 - Google Patents

一种通过常规造影图像测量出血流储备分数的方法 Download PDF

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WO2020215442A2
WO2020215442A2 PCT/CN2019/089200 CN2019089200W WO2020215442A2 WO 2020215442 A2 WO2020215442 A2 WO 2020215442A2 CN 2019089200 W CN2019089200 W CN 2019089200W WO 2020215442 A2 WO2020215442 A2 WO 2020215442A2
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blood flow
flow velocity
coronary
heart
measuring
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刘广志
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苏州润迈德医疗科技有限公司
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • A61B5/029—Measuring or recording blood output from the heart, e.g. minute volume
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/02028—Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal

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  • the invention relates to the field of coronary artery imaging evaluation, in particular to a method for measuring the bleeding flow reserve fraction through conventional angiography images.
  • Coronary angiography and intravascular ultrasound are considered to be the "gold standard" for the diagnosis of coronary heart disease, but they can only be used to evaluate the degree of stenosis of the lesion. However, it is not known how much the stenosis has on the distal blood flow; Fractional flow reserve (FFR) has now become a recognized indicator for functional evaluation of coronary artery stenosis. Its most important function is to accurately evaluate the functional consequences of an unknown impact of coronary artery stenosis.
  • FFR Fractional flow reserve
  • Fractional flow reserve refers to the ratio of the maximum blood flow that can be obtained in the myocardial area supplied by the target measurement vessel to the maximum blood flow that can be obtained in the same area under normal conditions in theory in the case of coronary artery stenosis.
  • pressure (P) flow (Q) * resistance (R)
  • vasodilators can be used to induce maximum congestion of myocardial microcirculation, which can make the myocardial microcirculation resistance (R) so small that it is negligible and constant Therefore, the definition of FFR can be transformed into the ratio of the mean pressure (P d ) in the coronary artery distal to the stenosis and the mean pressure (P a ) of the aorta of the coronary ostium in the state of maximum myocardial hyperemia, as shown in Figure 3.
  • the pressure at the aortic root can be obtained by a pressure sensor, while the pressure at the distal end of the stenosis needs to be measured at the maximum perfusion blood flow (by intracoronary or intravenous injection of papaverine or adenosine or ATP) through a pressure guide wire.
  • vasodilators such as adenosine or ATP
  • adenosine or ATP vasodilators
  • the technical scheme of the present invention is: a method for measuring bleeding flow reserve fraction through conventional contrast images, the conventional steps include:
  • vasodilator adenosine or ATP
  • vasodilator adenosine or ATP
  • the pressure decreases by 10%-15%
  • the microcirculation reaches the maximum congestion after 30-60s
  • the dilatation drug is continuously instilled while performing the same angiography in step 4
  • Contrast agent is injected by body position, and the blood flow velocity V h under the maximum hyperemia state can be calculated according to the contrast image;
  • ⁇ P is the pressure difference between the mean pressure of the coronary artery at the distal end of the stenosis and the mean pressure of the aorta at the orifice of the coronary artery in the state of maximum myocardial hyperemia.
  • the calculation method of ⁇ P is based on the coronal three-dimensional model to solve, and the continuity and Navier-Stokes equation are solved by numerical method:
  • P, ⁇ , ⁇ are flow velocity, pressure, blood flow density, blood flow viscosity, respectively.
  • u r and u z represent the flow velocity in z direction and r direction respectively.
  • the three-dimensional model For various types of coronary artery curvatures, use the three-dimensional model to calculate the pressure difference from the inlet to the outlet, and compare the results calculated by the two-dimensional axisymmetric model to establish a correction coefficient for storing the two-dimensional axisymmetric results of various types of curvature Data; use the calculation result of the three-dimensional model to correct the calculation result of the two-dimensional model to obtain the ⁇ P value.
  • the blood flow reserve score can be calculated.
  • the main purpose of the present invention is to not inject a vasodilator into the patient, and to calculate the blood flow velocity of the maximum hyperemia state only through conventional contrast images becomes a method based on the contrast blood flow reserve fraction.
  • the constant blood flow change value is based on clinical data Statistics, using the above routine steps to classify and count clinical trial subjects.
  • the conventional classification criteria include subject age, subject gender, subject health status, subject life habits, and so on.
  • two groups of characteristic categories can be formed, namely, strong cardiac function and weak cardiac function.
  • the blood flow velocity V′ h of the coronary artery of the heart when the microcirculation resistance is eliminated can be simulated based on the patient's conventional blood flow velocity. Then the simulated blood flow velocity V h is the blood flow velocity at the maximum congestion state of the myocardium, so the mean coronary artery pressure P d at the distal end of the stenosis at the maximum congestion state of the myocardium can be calculated.
  • the aortic pressure P a of the coronary ostium in the target area is acquired by the need for a sensor
  • the mean pressure P d of the coronary artery at the distal end of the stenosis at the blood flow velocity V h is calculated through a hydrodynamic algorithm.
  • the advantages of the present invention are: there is no need to use a vasodilator for the patient, and the patient is prevented from being unable to perform the FFR test due to intolerance or side effects. Moreover, it can shorten the operation time and save the operation cost and achieve the same effect as the pressure guide wire FFR, which becomes a good FFR detection method.
  • Figure 1 is a graph of the linear pressure change of the coronary artery of the heart
  • Figure 2A is an angiogram of the entire coronary artery circulation of the heart
  • Figure 2B is an angiogram of the branches of the coronary circulation vascular unit.
  • Figure 3 is a schematic diagram of FFR.
  • the main purpose of the present invention is to not inject a vasodilator into the patient, and to calculate the blood flow velocity of the maximum hyperemia state only through conventional contrast images, which becomes a method based on the contrast blood flow reserve fraction.
  • a blood flow change constant value ⁇ V to reflect the change between the conventional blood flow velocity of the coronary arteries of the heart and the blood flow velocity of the congested state of the coronary arteries of the heart; for example: analysis of the same person and the same blood vessel in the routine angiography state
  • the V c flow rate value is in the interval of 100mm/s ⁇ 200mm/s.
  • V h is distributed between 200mm/s ⁇ 400mm/s, and the slopes of the trend lines of the two sets of data are very close and have good consistency.
  • ⁇ V equal to the average difference between V h and V c as a constant value, and the range of the constant value is 20-400 mm/s.
  • the blood flow constant value ⁇ V is statistically based on clinical data of 200 cases.
  • the 200 clinical trial subjects include people with various myocardial states.
  • the average value is taken on the statistical data of 200 cases. Therefore, the applicable accuracy rate of the blood flow constant value ⁇ V can be as high as 90%.
  • the method of obtaining the blood flow constant value ⁇ V is still based on the conventional FFR detection step, that is, after injecting the core tube dilator into the clinical subject under coronary angiography.
  • the focus is on how to ensure that the coronary microcirculation is fully expanded, that is, through:
  • angiography is performed first, and the conventional blood flow velocity V c is calculated. Then the patient was given continuous intravenous injection of vasodilator (adenosine or ATP) at a drip rate of 140ug/(min*kg). By observing the change of P a , it first increases and then decreases, the pressure decreases by 10%-15%, the microcirculation reaches the maximum hyperemia state after 30-60s, and the dilatation drug is continuously instilled while the contrast agent is injected again. The angiographic image can calculate the blood flow velocity V h under the maximum hyperemia state.
  • vasodilator adenosine or ATP
  • the standard classification of group characteristics is carried out according to the individual conditions of the clinical trial subjects.
  • the conventional classification criteria include the subject's age, the subject's gender, the subject's health status, the subject's living habits, and so on.
  • two groups of characteristics can be formed according to the quality of the myocardium, namely, strong myocardial function and weak myocardial function.
  • the blood flow velocity V h of the coronary artery of the heart can be simulated and calculated when the microcirculation resistance is eliminated. Then the simulated blood flow velocity V h is the blood flow velocity at the maximum congestion state of the myocardium, so the mean coronary artery pressure P d at the distal end of the stenosis at the maximum congestion state of the myocardium can be calculated.
  • the aortic pressure P a of the coronary ostium in the target area is acquired by the need for a sensor
  • the mean pressure P d of the coronary artery at the distal end of the stenosis at the blood flow velocity V h is calculated through a hydrodynamic algorithm.
  • the feature point P1 is obtained after the catheter is refined, so the position of P1 must be in the catheter; although the position of the catheter in the target image and the reference image will change to some extent, the change must only be within a small range . Therefore, the area of the coronary artery can be determined according to the corresponding positional relationship between P2 and feature point P1;
  • the coronary angiography images taken at the same time point and at different angles in the heartbeat cycle are segmented according to the above steps, and feature points are extracted on the center line. Based on the known camera angle, these feature points are restored in three dimensions, and then the center line is restored in three dimensions.
  • the centerline and diameter of the coronary artery are projected and calculated in the three-dimensional space on the centerline of the coronary artery in multiple directions generated by the above steps to generate a three-dimensional model of the coronary artery to obtain the accurate blood vessel length L and diameter D.
  • the 3D model of coronary artery based on step reconstruction can use standard tracking methods (for example: contrast agent transit time algorithm, contrast agent traversal distance algorithm) to calculate blood flow velocity or use Stewart-Hamilton algorithm, First-pass distribution analysis method, optical flow Method, fluid continuous method to calculate blood flow rate.
  • standard tracking methods for example: contrast agent transit time algorithm, contrast agent traversal distance algorithm
  • Stewart-Hamilton algorithm First-pass distribution analysis method
  • optical flow Method fluid continuous method to calculate blood flow rate.
  • a structural or non-structural 3D mesh is created; and based on the reconstructed coronary artery centerline and diameter, the blood vessel is straightened and cut along the axis of symmetry to generate an axisymmetric 2D plane model. Then create structured or unstructured two-dimensional axisymmetric grids.
  • the standard sweep method is used for meshing to generate a structural three-dimensional hexahedral mesh; or other methods (for example: segmentation method, hybrid method) are used for meshing to generate structural Three-dimensional hexahedral mesh;
  • a triangular surface mesh is generated on the blood vessel wall and then grown into a tetrahedral mesh to generate an unstructured three-dimensional tetrahedral mesh in the blood vessel;
  • P, ⁇ , ⁇ are flow velocity, pressure, blood flow density, blood flow viscosity, respectively.
  • the inlet boundary condition is the blood flow velocity
  • the outlet boundary condition is the out-flow boundary condition;
  • u r and u z represent the flow velocity in z direction and r direction respectively.
  • the inlet boundary condition is the blood flow velocity
  • the outlet boundary condition is the out-flow boundary condition.
  • use a three-dimensional model to calculate the pressure difference from the inlet to the outlet, and compare the results calculated by the two-dimensional axisymmetric model.
  • a database used to store the correction coefficients of various types of bending to the two-dimensional axisymmetric results; use the three-dimensional model calculation results to correct the two-dimensional model calculation results to obtain ⁇ P;

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Description

一种通过常规造影图像测量出血流储备分数的方法 技术领域
本发明涉及冠状动脉影像学评价领域,特别是一种通过常规造影图像测量出血流储备分数的方法。
背景技术
冠状动脉造影及血管内超声均被认为是诊断冠心病的“金标准”，但它们只能对病变狭窄程度进行影像学评价，而狭窄到底对远端血流产生了多大影响却不得而知；血流储备分数(FFR)现已经成为冠脉狭窄功能性评价的公认指标，其最重要的功能是对一个未知影响的冠脉狭窄的功能后果进行准确评价。
血流储备分数(FFR)是指在冠状动脉存在狭窄病变的情况下，目标测量血管所供心肌区域能获得的最大血流量与同一区域理论上正常情况下所能获得的最大血流量之比。根据流体力学公式，压力(P)＝流量(Q)*阻力(R)，临床上可采用血管扩张剂诱发心肌微循环最大程度充血，可使心肌微循环阻力(R)小到忽略不计并恒定，因此FFR的定义可转化为心肌最大充血状态下的狭窄远端冠状动脉内平均压(P d)与冠状动脉口部主动脉平均压(P a)的比值，如图3所示。主动脉根部压力可以通过压力传感器获取，而狭窄远端压力则需要通过压力导丝在最大灌注血流(通过冠脉内或静脉内注射罂粟碱或腺苷或ATP)时测得。
但血管扩张药(如腺苷或ATP)对部分患者不耐受或有副作用，限制了FFR临床应用。因此对于这些不适用人群，FFR临床检测就无法正常实施。
发明内容
本发明的技术方案是：一种通过常规造影图像测量出血流储备分数的方法，常规步骤包括：
一、通过需要传感器获取患者目标区的冠状动脉口部主动脉压P a；
二、通过造影图像获取患者目标区的被测血管直径D及被测血管长度L；基于冠脉造影图像，并通过分析定义时间序列的造影不同帧，去除动静态噪声，对冠状动脉进行分割；并对不同角度拍摄的冠脉造影图像进行分割，分别得到冠脉中心线及直径。根据造影图像生成冠脉三维模型；在三维空间进行投影计算，生成冠脉三维模型，获取被测血管直径D及被测血 管长度L。
三、通过血流计帧法计算心脏冠状动脉的常规血流速度V c；对冠脉造影图像按时序帧进行扫描计算出造影剂从血管入口流到血管末端需要的时间，从而进一步得到常规血流速度V c。
四、给患者从静脉持续注射血管扩张剂(腺苷或ATP)，滴注速率为140ug/(min*kg)。通过观察P a的变化先升高再降低，压力降低幅度达到10％-15％，滴注时间在30-60s后微循环达到最大充血状态，持续滴注扩张药物同时再根据步骤四相同的造影体位推注造影剂，根据造影图像即可计算出最大充血态下的血流速度V h；
基于血流速度V h、冠状动脉口部主动脉压P a，通过流体力学算法计算血流速度V′ h下狭窄远端冠状动脉平均压P d＝P a-ΔP。ΔP即为心肌最大充血状态时狭窄远端冠状动脉平均压与冠状动脉口部主动脉平均压的压差。ΔP的计算方式是基于冠状三维模型进行求解，用数值法求解连续性和Navier-Stokes方程：
Figure PCTCN2019089200-appb-000001
其中
Figure PCTCN2019089200-appb-000002
P，ρ，μ分别为流速、压力、血流密度、血流粘性。
以入口边界条件为血流速度，出口边界条件为out-flow边界条件，用数值法求解连续性和Navier-Stokes方程：
Figure PCTCN2019089200-appb-000003
其中u r、u z分别表示z向、r方向的流速。
针对各种类型的冠脉弯曲，用三维模型计算从入口到出口的压力差，对照二维轴对称模型计算的结果，建立用于存储各种类型的弯曲对二维轴对称结果的修正系数的数据；利用三维模型计算结果修正二维模型计算结果得到ΔP值。
五、根据公式
Figure PCTCN2019089200-appb-000004
即可计算血流储备分数。
但本发明的主旨在于不对患者注射血管扩张剂，只通过常规造影图像来计算最大充血态的血流速度成为基于造影血流储备分数方法。
因此，需要定义一个血流变化常量值ΔV用于反映心脏冠状动脉的常规血流速度与心脏冠状动脉的充血状态血流速度之间的变化量；该血流变化常量值是基于对临床数据的统计，利用上述常规步骤对临床试验对象进行分类统计。根据临床试验对象的个体情况进行群体特征的标准分类，常规的分类标准包括对象年龄、对象性别、对象健康状况、对象生活习惯等等。最终可以形成两个群体特征类别，即心肌功能偏强、心肌功能偏弱。
当血流变化常量值ΔV具有相对较高的适用率时，就可以基于患者的常规血流速度模拟计算其心脏冠状动脉在消除微循环阻力时的血流速度V′ h。那么模拟出的血流速度V h即为心肌最大充血状态时的血流速度，因此可以计算出心肌最大充血状态时狭窄远端冠状动脉平均压P d。
基于血流变化常量值ΔV的模拟计算，患者的心脏冠状动脉在消除微循环阻力时的血流速度V h就可以快速推断出。那么上述常规方法可以改进为：
第一、通过需要传感器获取目标区的冠状动脉口部主动脉压P a；
第二、通过造影图像获取目标区的被测血管直径D及被测血管长度L；通过血流计帧法得到造影剂在目标区的被测血管中流动的时间t，常规血流速度
Figure PCTCN2019089200-appb-000005
第三、通过血流计帧法计算心脏冠状动脉的常规血流速度V c；
第四、基于常规血流速度V c、血流变化常量值ΔV，模拟计算目标区域的心脏冠状动脉在消除微循环阻力时的血流速度V h＝V c+ΔV；
第五、基于血流速度V h、冠状动脉口部主动脉压P a，通过流体力学算法计算血流速度V h下狭窄远端冠状动脉平均压P d。
第六、根据公式
Figure PCTCN2019089200-appb-000006
计算血流储备分数。
本发明的优点是：不需要对患者使用血管扩张剂，避免患者因为不耐受或副作用而无法进行FFR测试。而且能够缩短手术时间和节约手术费用并达到与压力导丝FFR同等的效果， 成为一种良好的FFR检测方法。
附图说明
下面结合附图及实施例对本发明作进一步描述：
图1是心脏冠状动脉的压力线性变化图；
图2A是整个心脏冠状动脉循环血管的造影图；图2B是冠状动脉循环血管单元分支的造影图。
图3是FFR的原理图。
具体实施方式
实施例：
本发明的主旨在于不对患者注射血管扩张剂，只通过常规造影图像来计算最大充血态的血流速度成为基于造影血流储备分数方法。
因此，需要定义一个血流变化常量值ΔV用于反映心脏冠状动脉的常规血流速度与心脏冠状动脉的充血状态血流速度之间的变化量；例如：分析同一个人同一根血管在常规造影状态下计算的血流速度V c和最大充血状态的血流速度V h的相关性，推导出由于微循环扩张引起的血流速度变化ΔV＝V h-V c。统计所有临床数据中V c分布80％的案例，V c流速值在100mm/s～200mm/s区间。对应的V h分布在200mm/s～400mm/s之间，并且两组数据趋势线斜率非常接近有良好的一致性。计算ΔV等于V h和V c的平均差为一个常量值，常量值的范围为20-400mm/s。
基于上述的基础理论，该血流变化常量值ΔV是基于200例的临床数据统计所得。这200例的临床试验对象包括多种心肌状态的人群，在200例的统计数据上取均值，因此该血流变化常量值ΔV的适用准确率可以高达90％以上。
该血流变化常量值ΔV的获取方式还是基于常规的FFR检测步骤，即在冠状动脉造影下对临床对象注射芯管扩张剂后所实现的。其重点在于如何确保冠状动脉的微循环处于充分扩张状态，即通过：
通过临床试验，先做造影手术，计算出常规血流速度V c。然后给患者从静脉持续注射血管扩张剂(腺苷或ATP)，滴注速率为140ug/(min*kg)。通过观察P a的变化先升 高再降低，压力降低幅度达到10％-15％，滴注时间在30-60s后微循环达到最大充血状态，持续滴注扩张药物同时再推注造影剂，根据造影图像即可计算出最大充血态下的血流速度V h。
具体的，根据临床试验对象的个体情况进行群体特征的标准分类，常规的分类标准包括对象年龄、对象性别、对象健康状况、对象生活习惯等等。最终可以根据心肌质量形成两个群体特征类别，即心肌功能偏强、心肌功能偏弱。
序号 心肌质量 血流变化常量值ΔV
1 心肌功能偏强 100-400mm/s
2 心肌功能偏弱 20-300mm/s
基于该血流变化常量值ΔV值，就可以模拟计算其心脏冠状动脉在消除微循环阻力时的血流速度V h。那么模拟出的血流速度V h即为心肌最大充血状态时的血流速度，因此可以计算出心肌最大充血状态时狭窄远端冠状动脉平均压P d。
基于血流变化常量值ΔV的模拟计算，患者的心脏冠状动脉在消除微循环阻力时的血流速度V h就可以快速推断出。那么上述常规方法可以改进为：
第一、通过需要传感器获取目标区的冠状动脉口部主动脉压P a；
第二、通过造影图像获取目标区的被测血管直径D及被测血管长度L；通过血流计帧法得到造影剂在目标区的被测血管中流动的时间t，常规血流速度
Figure PCTCN2019089200-appb-000007
第三、通过血流计帧法计算心脏冠状动脉的常规血流速度V c；
第四、基于常规血流速度V c、血流变化常量值ΔV，模拟计算目标区域的心脏冠状动脉在消除微循环阻力时的血流速度V h＝V c+ΔV；
第五、基于血流速度V h、冠状动脉口部主动脉压P a，通过流体力学算法计算血流速度V h下狭窄远端冠状动脉平均压P d。
第六、根据公式
Figure PCTCN2019089200-appb-000008
计算血流储备分数。
上述方法步骤中涉及到的具体操作内容包括：
1：提取冠脉造影图像：
首先对造影图像中的导管进行图像增强：
a)定位导管区域，除去部分静态噪声；
b)做均值滤波，除去部分动态噪声；
c)通过灰度直方图分析，利用阈值进一步去噪；
d)将去噪后的图像进行多尺度海森矩阵，对导管进行图像增强，得到增强后的导管图像；
e)二值化图像，将导管对应的像素标记为1，其余像素标记0；
f)对二值化后的图像进行细化，得到导管的特征点P1。
其次，对目标图像中的冠状动脉进行图像增强：
g)定位冠状动脉区域，除去部分静态噪声；
h)均值滤波，除去部分动态噪声；
i)通过灰度直方图分析，利用阈值进一步去噪；
j)将去噪后的图像进行多尺度海森矩阵，对冠状动脉进行图像增强，得到冠状动脉的特征点P2。
通过对冠状动脉区域进行以上操作得到的图像中，除被增强后的冠状动脉之外，还可能有被海森矩阵误认为管状物而进行了增强的噪声。于是需要将该图像中冠状动脉和噪声进行区分。
k)特征点P1是由导管细化后得到的，所以P1的位置一定在导管中；目标图像和参考图像中，导管的位置虽然会有一定变化，但是该变化必定只是在一个小范围内的。所以，可以根据P2与特征点P1的对应位置关系，确定冠状动脉的区域；
l)提取k中冠状动脉的区域，获得图像。最后，以特征点P1为种子点，将该图像进一步处理后进行动态区域生长，获得结果。
m)对l中的图像二值化、形态学运算，并按照对应位置还原到目标图像中，进行动态区域生长，得到结果图像。
2：生成冠脉三维模型：
对心跳周期内相同时间点、不同角度拍摄的冠脉造影图像按照上述步骤进行分割，在中心线上提取特征点，基于已知的拍照角度，三维还原这些特征点，进而三维还原中心线，得到冠脉中心线及直径，将上述步骤生成的多个方向的冠脉中心线在三维空间进行投影计算，生成冠脉三维模型，获取准确的血管长度L和直径D。
3：计算冠脉血流速度：
对冠脉造影图像按时序帧进行扫描计算出造影剂从血管入口流到血管末端需要的时间t，再通过血管长度除以时间得到常规血流速度
Figure PCTCN2019089200-appb-000009
基于步重构的冠脉三维模型，可以用标准的跟踪法(例如：造影剂运输时间算法、造影剂遍历距离算法)计算血液流速或者使用Stewart—Hamilton算法、First—pass分布分析法、光流法、流体连续法计算血液流速。
4：冠脉网格划分：
基于重构的冠脉三维模型，创建结构性或者非结构性三维网格；并基于重构的冠脉中心线及直径，拉直血管，按对称轴切开，生成轴对称二维平面模型，然后创建结构性或者非结构性二维轴对称网格。
基于重构的冠脉三维模型，用标准的扫掠法进行网格划分，生成结构性三维六面体网格；或者用其它方法(例如：切分法、混合法)进行网格划分，生成结构性三维六面体网格；
基于重构的冠脉三维模型，在血管壁上生成三角形面网格，然后长成四面体网格，在血管中生成非结构性三维四面体网格；
基于重构的冠脉三维模型，拉直血管，按对称轴切开，生成轴对称二维平面模型，用切分法或者扫掠法进行网格划分，生成结构性二维四边形网格。
5：冠状动脉FFR计算：
1)三维模型
基于造影图像重构的几何结构，划分三维网格，用数值法(如：有限差分、有限元、有限体积法等)求解连续性和Navier-Stokes方程：
Figure PCTCN2019089200-appb-000010
其中其中
Figure PCTCN2019089200-appb-000011
P，ρ，μ分别为流速、压力、血流密度、血流粘性。入口边界条件为血流速度，出口边界条件为out-flow边界条件；
通过公式
Figure PCTCN2019089200-appb-000012
计算沿着血管中心线从入口到下游各点的血流储备分数，其中，P a是主动脉平均压，ΔP是沿着血管中心线从入口到下游各点的压力降。
2)二维模型
基于线造影重构的几何结构，把有狭窄的血管拉直(二维轴对称模型)，划分二维网格，用数值法(如：有限差分、有限元、有限体积法等)求解连续性和Navier-Stokes方程：
Figure PCTCN2019089200-appb-000013
其中u r、u z分别表示z向、r方向的流速。
入口边界条件为血流速度，出口边界条件为out-flow边界条件；针对各种类型的冠脉弯曲，用三维模型计算从入口到出口的压力差，对照二维轴对称模型计算的结果，建立用于存储各种类型的弯曲对二维轴对称结果的修正系数的数据库；利用三维模型计算结果修正二维模型计算结果得到ΔP；
通过公式
Figure PCTCN2019089200-appb-000014
计算沿着血管中心线从入口到下游各点的血流储备分数。
上述实施例仅例示性说明本发明的原理及其功效，而非用于限制本发明的。任何熟悉此技术的人士皆可在不违背本发明的精神及范畴下，对上述实施例进行修饰或改变。因此，举凡所属技术领域中具有通常知识者在未脱离本发明的所揭示的精神与技术思想下所完成的一切等效修饰或改变，仍应由本发明的权利要求所涵盖。

Claims (9)

  1. 一种通过常规造影图像测量出血流储备分数的方法，由心肌最大充血状态时狭窄远端冠状动脉平均压与冠状动脉口部主动脉平均压求比值；其特征在于：定义一个血流变化常量值用于反映心脏冠状动脉的常规血流速度与心脏冠状动脉的充血状态血流速度之间的变化量；基于目标对象的常规血流速度模拟计算其心脏冠状动脉在消除微循环阻力时的血流速度，且该血流速度下计算心肌最大充血状态时狭窄远端冠状动脉平均压。
  2. 根据权利要求1所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：基于对象群体，所述血流变化常量值至少可按照两个群体特征进行标准分类。
  3. 根据权利要求2所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：形成所述血流变化常量值的两个群体特征的为心肌强度。
  4. 根据权利要求2或3所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：所述血流变化常量值以心脏冠状动脉血管充分扩张状态的临床试验数据为基础。
  5. 根据权利要求4所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：心脏冠状动脉的充血状态血流速度是在临床对象注射血管扩张剂后的实时造影测试结果。
  6. 根据权利要求5所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：心脏冠状动脉血管充分扩张状态是通过对临床对象静脉持续注射腺苷或ATP，且滴注速率为140ug/(min*kg)，观察其冠状动脉口部主动脉压的变化，当冠状动脉口部主动脉压的压力降低幅度达到10％～15％，滴注时间保持30～60s后达到充分扩张状态。
  7. 根据权利要求1或6所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：该方法的具体步骤为：
    第一、通过需要传感器获取目标区的冠状动脉口部主动脉压P a；
    第二、通过造影图像获取目标区的被测血管直径D及被测血管长度L；
    第三、通过血流计帧法计算心脏冠状动脉的常规血流速度V c；
    第四、基于常规血流速度V c、血流变化常量值ΔV，模拟计算目标区域的心脏冠状动脉在消除微循环阻力时的血流速度V h＝V c+ΔV；
    第五、基于血流速度V h、冠状动脉口部主动脉压P a，通过流体力学算法计算血流速度V h下狭窄远端冠状动脉平均压P d。
    第六、根据公式
    Figure PCTCN2019089200-appb-100001
    计算血流储备分数。
  8. 根据权利要求7所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：所述第二步中：基于二维的造影图像，同一区域不同角度体位的造影图像组合成三维血管模型。
  9. 根据权利要求8所述的一种通过常规造影图像测量出血流储备分数的方法，其特征在于：所述第三步中：通过血流计帧法得到造影剂在目标区的被测血管中流动的时间t，常规血流速度
    Figure PCTCN2019089200-appb-100002
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