Method for calculating index of microcirculatory resistance based on myocardial blood flow and CT image

A method for calculating an index of microcirculatory resistance based on myocardial blood flow and CT image, comprising the following steps:

• S01:
• segmenting the CT image of heart, obtaining an image of heart via a morphological operation, subjecting the image of heart to a histogram analysis to obtain an image contains ventricular and atrial, obtaining a myocardial image by making a difference between the image of heart and the image contains ventricular and atrial, determining a myocardial volume by the myocardial image;
• S02:
• obtaining a full aortic complementary image by processing an aortic image, obtaining the aortic image containing a coronary artery inlet through regional growth of the full aortic complementary image, and obtaining an image containing the coronary artery inlet according to the aortic image containing the coronary artery inlet and the full aortic complementary image, to determine the coronary artery inlet by the image containing the coronary artery inlet;
• S03:
• extracting a coronary artery through regional growth by taking the coronary artery inlet as a seed point on the myocardial image, calculating an average gray and average variance of the coronary artery, and along a direction of the coronary artery, extracting a coronary artery tree according to a gray distribution of the coronary artery;
• S04:
• binarizing the coronary artery image, drawing an isosurface image to obtain a three-dimensional grid image of the coronary artery;
• S05:
• calculating a total flow at the coronary artery inlet in a maximum hyperemia state, Qtotal=myocardial volume×myocardial blood flow×CFR, and CFR being the coronary flow reserve;
• S06:
• calculating a blood flow velocity V1 in a hyperemia state and an average conduction time Tmn in the maximum hyperemia state;
• S07:
• calculating a pressure drop ΔP from the coronary artery inlet to a distal end of a coronary artery stenosis using V1 as an inlet flow velocity of coronary artery stenosis blood vessel, and using Pd=Pa−ΔP calculating a mean intracoronary pressure Pd at the distal end of the coronary artery stenosis, wherein Pa is a mean aortic pressure, and obtaining the index of microcirculatory resistance using IMR=Pd*Tmn.