| Cardiovascular disease (CAD) is the most dangerous factor threatening the human’s healthy with the characters of highly sickness rate and death. Because of coronary artery’s stenosis which is caused by atherosclerosis or vasospasm, the blood flow decreases, influencing the myocardium’s function. Therefore, it is very important to diagnose the CAD earlier.The traditional diagnostic method is digital subtraction angiography (DSA), which is the "golden standard". However, DSA has the shortages of high expense, harmful, complex diagnose process and so on. It is not a suitable choice of early diagnosis. For the past few years, with the fast development of multi-slice spiral computed tomography (MSCT), coronary artery computed tomography angiography (CTA) has been widely used for CAD diagnosis. It has the advantages of low expense, no harm, simply operating and offering multi-view. Nevertheless, the doctor cannot obtain useful information directly by looking over the CTA slice by slice. So, it is very necessary to process the CTA with the help of computer technology and image processing techniques. How to segment the coronary artery accurately and acquire its parameters is an important task.Because of the coronary artery’s scatter and the interference of other organizations in the CTA images, it is difficult to segment coronary artery. Under the research of image processing and segmentation algorithms, the dissertation proposes a method based on Hessian matrix enhancing filter and region growing to segment the coronary artery automatically. Then we can make a measurement of the coronary artery, obtaining quantitative information. The dissertation carried out the following task:● The automatically segment of ascending aorta. Firstly, based on the information of coronary’s similarity to circle in CT, using the method of image transformation to locate and segment it in the first slice. Then, the upper slice’s barycenter acts helps the under layer’s segmentation, along with the controlling of segmented region, avoiding over-segmentation. Lastly, repeat the segment process in all slices until the region segmented has a sudden arise.● The automatically segment of coronary artery. Firstly, make preprocessing to the images, restraining the lung area. Then, use the hessian matrix enhancing filter to enhance the contrast between the coronary artery and other organizations, making preparation to the integral region grow. Lastly, take the location of ascending aorta as the seed and use region grow method to segment the syncretic data of the segmented ascending aorta and the enhanced images. The coronary artery can be obtained by subtracting the ascending aorta.● The analysis on vascular stenosis degree. The dissertation uses a method based on the tracing of the points in the vascular. Firstly, make an initialization, including the start point, the end point, the length of step and the direction. Then, according the initialization, find the next point in vascular and take the barycenter of the cross section as the valid point we find iteratively. Lastly, calculate the area of every point’s cross section and make an analysis on vascular stenosis degree. |
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