Research On The 2D Information Processing And 3D Reconstruction Of Heart Vessel In Angiogram

The heart vessel angiogram is the gold tool for diagnosing the presence of coronary artery disease. The traditional methods suffer from inter- and intra-observer variability, so it is very important to develop an objective and precise system to auto-diagnose coronary disease. The image of the 3-D heart vessel reconstructed from 2-D angiograms with different angles naturally and quantitatively depicts the vessel stenosis, and the 3D reconstruction is helpful to prevent and cure the stenosis. The procedure of the 3-D reconstruction is divided into two steps: one is to get the 2-D heart vessel informations from the angiogram; the other is to reconstruct 3D vessel. The main work of this thesis is carried out about the detection of the vessel skeleton and boundary, auxiliary diagnosis and of the stenosis of the main vessel and 3-D reconstruction. The works can be included in five parts as follows:1,Analysis of the intensity characters of the heart vessel angiogramThe heart vessel angiogram is deeply analyzed on the base of the imaging theory and the vascular shape. Six intensity characteristics are acquired, which are the rules for the detection of the 2-D information in the angiogram.2,Detection of the heart vessel skeletonImage pre-processing technologies are firstly used to eliminate noise and enhance the image, such as Top-Hat transform, the rotated 1-D Gauss template and so on. Then the self-adaptive tracking circle template is addressed to extract the vessel area on the research of the self-adaptive threshold, maximum classes square error, et al. After initialized by manual supervision, it can get the vessel area from the angiogram enhanced by the rotated 1-D Gauss template. At last, the un-direct method that thins the vessel area as the skeleton is adopted on the research of the direct and un-direct methods. The connectivity-number thinning method is presented to skeletonize the vessel area. It possesses virtues of small computation, low time-cost, isotropy, and so on. 3,Detection of the continuous vessel boundaryThe continuous vessel boundary is the base for measuring the diameter of the 3-D reconstruction and diagnosing the vessel stenosis. The Max-Cost(MC) is presented on the base of the studies of the traditional edge detecting methods and Wavelet. It is consisted of two steps: the fist step is that the cost field is built up by the traditional edge detecting method—differential method; The second step is that the boundary, the curve with maximal cost in the segmented area, is detected serially by the dynamic programming (DP). The MC inherits the merits of the traditional method, and its boundary is continuous and one-pixel wide. The minimal diameter of the vessels whose boundary can be detected reaches 1mm. 4,The diameter measurement and auxiliary diagnose of the main vesselThe diameter measurement and auxiliary diagnosis are based on the skeleton and continuous boundary of the heart vessel. The vessel is re-sampled by the skeleton, and the minimal distance of the vessel edge of the re-sampled point is defined as the corresponding vessel diameter. The linear fitting is used to weaken the discrete error of the diameter. Then the vessel diameter information detected by the above method is used to diagnose the vessel stenosis, and its result is well consistent with the diagnoses of experienced doctors. 5,Research on the heart vessel 3-D reconstructionThe model of the 3-D heart vessel and 3-D reconstruction, the measurement of the diameter for 3-D reconstruction and description of the vessel tree are briefly studied. This thesis presents that the binary tree is used to descript the vessel tree, store the data and traverse the information. It makes preparation for the matching of vessel skeleton point in the process of 3-D reconstruction and supplies a good data surface.