Research On Sphere Model-based3D Coronary Artery Centerline Extraction Method

Coronary heart disease(CVD) is a global health problem and is one of the major diseasesthat threaten human health, coronary heart disease has become the major lethal disease in allcountries of the world since the1950s, the incidence of CVD continued to show an upwardtrend in n recent years, it has become a major catastrophic illness of humanity today.According to the most recent statistics by the World Health Organization (WHO) on May2014, there are740million people worldwide die from coronary heart disease and in the firstrow of all death causes of the world. Coronary CT angiography(CCTA) is a non-invasivevascular imaging technique, it can not only provide the anatomic structure of the coronaryartery, but also can provide pathological information such as extent and scope of calcification,soft plaque boundary, deformity, stenosis and infarction, and it is a common and effectivemethod of diagnosing coronary artery atherosclerosis heart disease. How to make full use ofthe valuable information in coronary computed tomography angiography image has importantimplications for the clinical diagnosis of coronary atherosclerosis, rating, treatment andoperation planning.Coronary artery segmentation is an important application direction of medical vascularimage segmentation, it is also a research focus of image segmentation, it not only can relievethe doctor out from the tedious and time-consuming work of delineating the coronary arteryby manual, and it is also an essential component of image post processing tools such ascoronary artery visualization, multi planar reformation and curved planar reformation, it is animportant means of correct evaluation,in particular, precise visualization and quantificationof coronary arteries.The coronary artery is a complex network composed of a curved pipelinein the space, combined with coronary artery ct angiography image noise, motion artifacts andfuzzy diseased tissue, all this factors make it is very difficult to extracted accurately andrapidly the center line of the coronary arteries.Although many scholars have done a lot ofresearch work for coronary segmentation and put forward a number of coronarysegmentation methods, but this methods are still not fully up to the task, it is still achallenging task to segment fastly and accurately coronary angiography images withautomatic or Semi-automatic3D segmentation methods.This paper mainly focus on three dimensional coronary artery centerline extractionmethods in coronary artery ct angiography image, and present a novel sphere model basedthree-dimensional coronary artery centerline semi-automatic extraction method.The centerlineextraction results in this paper were analyzed and compared with existing coronary artery centerline extraction methods were, comparison result shows that the proposed algorithm hasfaster extraction speed, strong extractionability and high extraction accuracy. More concretely,the main contributions include:1、Proposing a novel algorithm of sphere model based three dimension coronary arterycenterline extraction(SM3DCACE). Coronary artery is the network which supply blood forheart, originated from the aortic root,and then divided into two branches. Coronary artery is aresilient and scalable pipeline system, and vessel cross section perpendicular to the flowdirection is approximately circle. According to above characteristics of the vascularsystem,animaginary sphere with variable size inaccordance with the pre-specifie dconditions, startingform a specified location of the coronary artery, goes along the direction of blood flow in theprocess of centerline extraction. When the sphere moves to a new position of the coronaryartery,the center and radius of this sphere are continuously adjusted according to the size ofthe inner diameter o fcoronary artery so that this sphere is the maximumin scribed sphere ofall spheres at current position. When the sphere encounters the bifurcation, the sphere is splitinto two spheres, and then the splitting sphere respectively goes along the branches ofcoronary artery according to this method until the sphere to meet the requirements can not befound. Finally, the center of sphere at the respective positions is connected, and thisconnection line constitutes the centerline of the entire coronary artery.The extraction resultpresent this algorithm can extract three main branches of coronary artery.2、Presenting a new algorithm sphere model based3D coronary artery centerlineextraction with branch detection (SM3DCACEBD). Aiming at the lack of SM3DCACEmethod for vascular branch detection, a branch detection algorithm is proposed combinedwith ray casting and cluster. The radius of sphere in a researching position to increasedrespectively by1,2and3, and three new spherical is obtained, and then rays from the centerof original sphere evenly emit to outer sphere,the rays meeting the predefined criteria andreach the outermost sphere is retained, the last remaining ray clustering according topredefined criteria, the number of cluster which is obtained by clustering can determine thewhether there is branch on the position of current sphere,and how many vascular branches inthis position. some branches. Real coronary angiograms are use to verify the presentedalgorithm, the result shows that this algorithm can extract more vascular branch and branchshape more clearly than SM3DCACE.3、Longitude and latitude coordinates sphere model based3D coronary artery centerlineextraction(LLCSM3DCACE) algorithm is proposed. Sphere model used by SM3DCACE and SM3DCACEBD is based on carbon60(C60) molecular model, because there are only60points in the surface of C60, which makes the detection points are too sparse, it is difficult todetect the small branches of the coronary arteries, and small branches which have revelantclinical diagnosis value of coronary artery disease may miss out.With the aid of earthlongitude and latitude coordinates system, a new longtitued and latitude sphere model isproposed in this paper.The number of detection points on sphere can be changed throght theappropriate adjustment of the difference of longitude and latitude between two adjacentlongitude coilor two adjacent latitude coil, so as to enhance the ability of extracting smallcoronary branches.Proposed exatraction algorithm in this paper is tested and evaluated usingRotterdam Coronary Artery Algorithm Evaluation Framework(RCAAEF), the comparisonand evaluated results show proposed algorithm in this paper has good performance.