| In recent years, coronary artery disease (also called coronary heart disease) morbidity and mortality all showed a trend of rising in the whole world, is one of the primary diseases that affect human life. Coronary heart disease (CHD) that occurred coronary arterial atherosclerosis lesions caused by vascular cavity stenosis or occlusion, cause myocardial ischemia, hypoxia or necrosis caused by heart disease. The world health organization of coronary heart disease can be divided into five categories:asymptomatic myocardial ischemia (occult) coronary heart disease, angina pectoris, myocardial infarction, ischemic heart failure, ischemic heart disease and sudden death 5 kinds of clinical type.Applied for clinical diagnosis and treatment of Coronary heart disease in the main image means including X-ray Coronary Angiography (Coronary Angiography,) and ultrasonic inside (Intravascular Ultrasound, IVUS) . The CAG is an invasive examination, through special shape of cardiac catheterization percutaneous femoral artery puncture (or brachial artery), along the descending aorta retrograde to ascending aorta root, then explore the left or the right coronary artery is inserted, the injection of contrast agent, by observing the contrast agents in the filling within the blood vessels to observation vascular anatomy structure, can be clearly to the left or right coronary artery trunk and its branches (hereinafter referred to as "coronary") of vascular cavity, can exist know blood vessels have narrow lesions and cardiac function, blood supply and hidden heart throb cycle blood vessels in the deformation, convenient for clinical doctors to the position and size of lesions, severity, and the condition of blood vessel walls make a definite diagnosis, treatment decision. Therefore, is known as the "gold standard" of detection of coronary heart disease diagnosis. IVUS technique is usually based on clinical doctors after selectively the CAG examination, according to the actual needs of patients with a kind of the ct imaging technology. In under the guidance of coronary angiography, the thread will deliver IVUS catheter to target the far side of the lesion site, under the uniform motor traction retracement ultrasound probe, by ultrasonic display screen can be observed in a series of cross-sectional images of blood vessels. IVUS high image resolution, can accurately obtain wall thickness, lumen morphology and composition of atherosclerotic plaque and other information. Quantitative analysis of the sequence of IVUS vascular and lumen area, volume, maximum minimum diameter, narrow lumen area rate, diagnosis indexes such as patch load, to evaluate the coronary angiography is difficult to diagnosis and hidden lesions, guide the interventional treatment scheme and evaluate the effect of the treatment, sequence determination of plaque progression and reverse provides the basis for clinical application,is a clinical doctor for atherosclerosis radiographic assessment of one of the important standard. At present, drug therapy and coronary artery bypass surgery and interventional therapy are three main methods in the treatment of coronary heart disease, of which especially in the interventional treatment of development is rapid, become an important treatment relieve angina. Coronary artery bypass surgery and interventional treatment technology without auxiliary coronary angiography, and the imaging technique of ultrasound as a new inside also has become the important technical means in diagnosing coronary heart disease, both in medical diagnosis, preoperative and postoperative monitoring, medical treatment etc.) plays an important role.The CAG and IVUS image from 2D perspective to observe coronary vascular exist various limitations, coronary vascular reconstruction of 3D visualization of medical image has become a current research hot spot. By the earliest Wahle proposed fusion the CAG and IVUS both coronary artery of the 3D model reconstruction, is based on these two kinds of medical image from different levels reflects the morphological characteristics of coronary blood vessels. On the one hand, although the CAG can display coronary artery lumen of two-dimensional contour, but objectively restricts the detailed analysis of the cross section of the lesion site, not to the degree of pathological changes, the nature of the atheromatous plaque make accurate judgment. IVUS images, on the other hand, to perform well in the artery wall complex anatomical structures, but the lack of the integrity of arterial observation, in addition, ultrasound catheter physical size in severe stenosis and blood vessels may cause vasodilation, limit the accurate measurement of blood vessels. Given the CAG and IVUS images complementary on the function, the fusion of the CAG and IVUS images,3D reconstruction of arteries and blood vessels not only retained the radial information, at the same time provide doctors with intuitive, image, and easy to analyze three-dimensional vascular image, also can reflect the characteristics of the artery blood wall morphology, better assist clinicians to coronary heart disease (CHD) for clinical evaluation .At present, the application of these two kinds of image structures coronary three-dimensional model of the method has a lot, mainly can be divided into four stages :(1) image acquisition:refers to the CAG and IVUS image acquisition (IVUS image preprocessing, including removing noise and depicting the blood vessel edge contour extraction of two parts (3) the CAG vascular image 3D reconstruction: application of the CAG image reflects spatial structure information of coronary vascular reconstruction three-dimensional contours of coronary blood vessels. (4) the CAG IVUS image fusion model in three dimensions:IVUS image fusion after different algorithm to 3D models corresponding to the position.Applied the CAG structure, three-dimensional vascular model Prause et al. pointed out that the catheter path approximation as coronary artery vascular axis, in fact, don't agree with each other to keep on the vascular axis, catheter path for some smaller curvature vascular segment, this approach may seem easy to implement, but for some curvature is bigger, the wall structure of complex vessel segment will directly lead to serious distortion of reconstruction of three-dimensional vascular model in addition, the method also ignores the ultrasonic probe in the endovascular deflection, seriously affected the reconstruction of the authenticity and reliability of the results. Part of literature [6,9,10] using multi-angle projection coronary blood vessels, angiographic images have different, according to the imaging parameters such as distance and Angle, and under different angles of multiple points to identify (vascular branch point, support, etc.), using the SNAKE model complete vascular reconstruction of the model. In practice, however, multi-angle projection, for serious aliasing artifacts more images to choose suitable and reliable identification point is quite time consuming, in two or more image is also very difficult, need to find the same landmark for vascular reconstruction precision of the 3 d model. In addition, also need to make a space reconstruction to the path of the catheter, to assist in the correction of vascular axis, increased the amount of calculation.In the stage of the fusion, and acoustic characteristics based on the characteristics of IVUS image acquisition, the standard of intravascular ultrasound system display for single cross-sectional images geometry of video sequence, the literature think IVUS images should be perpendicular to the contour surface of blood vessels in the process of fusion inserted, including Ma et al. in IVUS image fusion to three-dimensional vascular model in the process, assuming that IVUS image acquisition plane orthogonal to the surface of blood vessels, and directly put to the IVUS images in vascular model. In fact, in the process of clinical acquisition IVUS images, because the heart beat or other physiological and physical factors cause the disturbance of ultrasonic mechanical probe, make IVUS image acquisition plane is not perpendicular to the surface of blood vessels (and blood vessels are long axis vertical), resulting in the phenomenon of IVUS image cant imaging. Especially some circuitous blood vessel distortion is more obvious. Accordingly, this assumption is not correct, for some cant imaging IVUS images, will directly cause the IVUS lumen area is greater than the corresponding real cross-section lumen area of the CAG images, if the vertical Angle to insert to the 3 d model, cause overflow IVUS image three-dimensional model range, on the premise of this 3 d reconstruction can lead to the final result serious distortion.Aiming at the shortcoming, in this paper, on the basis of the CAG, the Quantitative Analysis method of auxiliary in computer (policy Coronary Analysis, QCA), need only two or three in the CAG images corresponding points, can complete 3D visualization of arterial reconstruction. Cant imaging for IVUS images, using IVUS image sequences in the adjacent frame information, before and after comparison of IVUS image in the lumen of blood vessels in the radial difference, IVUS images with vascular cross section deflection Angle, while in judging IVUS frames in coronary blood vessels in the front, in the blood vessels of IVUS image after adjustment for Angle on the 3D model,3D model in coronary IVUS the corresponding position of the fusion image, the vascular model more truly reflect the actual anatomy structure of coronary artery, provided an important reference information for clinical diagnosis.So this article puts forward the key technology and main research contents include:Part1,3D model the CAG image build coronary vessels; Part2, using IVUS images before and after the frame information for IVUS insertion Angle correction model.Part1,3D model, build the CAG image coronary vessels mainly includes the following steps: ? choose two projection Angle for at least 25 ° and the peak of the late diastolic coronary angiography images. ? on the two angiogram choose two or three markers used in projection correction, ?rtificial selection target blood vessels, and identified target contour of the blood vessels, confirm the vessel centerline.? after confirm the corresponding relations between the center of the two images of blood vessels contour reconstruction of vascular centerline and blood vessels. Compared with the traditional fusion method, the reconstruction process doesn't need to analyze the catheter path data. Experiments show that this method not only provides reliable coronary vascular model at the same time it has a simple implementation, fast computing speed, etc.Part2, using IVUS images before and after the frame information for IVUS insert model Angle correction, first of all, the analysis of coronary arteries in the CAG and IVUS images of radial information difference, calculate the IVUS frames in the imaging process of ultrasonic mechanical probe offset Angle. Second, the application of Active Demons algorithm to judge the IVUS frames in fusion toward in the 3D model. Finally, the Angle after the correction of IVUS image data fusion to three-dimensional skeleton model, complete the fusion of two kinds of data. Experiments show that the method can significantly improve because of IVUS angular deviation caused by IVUS image distortion in the 3D model, the coronary artery more meet the needs of the clinical application of 3D reconstruction results.Zhu Jiang hospital, Guangzhou city, Guangdong province, this paper takes real clinical data as the experiment basis for patients with coronary heart disease, coronary artery is realized by using this algorithm of 3D reconstruction of blood vessel and IVUS fusion model of three-dimensional vascular Angle correction. By clinical experts manual segmentation of the accuracy of the results as the result of the experiment, the method for quantitative analysis. Make up the lack of experimental data and simulation experiment, the result of the correction for qualitative analysis. Compared with current methods, the precision of the reconstruction results have greatly improved, to prove the accuracy and authenticity by this method. |
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