【作者】 彭维雪；

【导师】 桑农；

【作者基本信息】 华中科技大学 ， 模式识别与智能系统， 2006， 硕士

【摘要】 数字减影血管造影技术(Digital Subtraction Angiography,简称DSA)是一种广泛使用的血管可视化技术,在临床已应用20多年,是血管疾病无创诊断与介入治疗的重要依据,广泛应用于X射线序列成像中的血管的可视化系统中。本文主要研究数字减影血管造影三维重建过程中的血管分割、中轴提取以及血管的三维表达问题。血管分割是DSA三维重建的基础,本文针对减影效果较好的DSA图像提出了知识导引的血管造影图像局部阈值分割方法。在血管直径先验知识的指导下将图像分成适当大小的若干子块,引入血管存在性判据,采用有重叠的图像分块技术对各子块进行局部阈值分割,再融合各子块分割结果。针对脑部和肝部DSA图像进行实验后,结果表明本文所提出的方法可以快速有效的分割出血管结构。中轴提取方面提出了基于多尺度Gabor滤波的方法对血管进行跟踪提取中轴。Gabor滤波器灵活的方位带宽和频率带宽使得血管中轴得到很好的增强,在增强后的响应图上人工选取各分支起点和终点,用最短路径法进行跟踪。对血管进行半自动分支跟踪可以解决血管的交叉,临近血管的区分,重叠等问题,使提取的中轴清晰准确。血管三维表达方面,先简短的介绍了三维表达前所必须的步骤:两个不同视角图的配准和骨架重建,再重点介绍基于广义圆柱模型(Generalized Cylinder)的血管三维表达。其中包括提取血管三维重建半径,对三维血管中轴进行平滑和为了得到血管横截面上圆周的三维坐标所进行的空间直角坐标变换。该方法简单效率高,能很好的显示完整的三维血管。最后是通过血管的表面绘制方法,利用VTK对血管进行三维显示。此方法绘制速度快,显示结果逼真有立体感。更多还原

【Abstract】 Digital subtraction angiography (DSA) is a widely used technique for the visualization of blood vessels in the human body and has been used in clinic for more than 20 years,which has significant values in the diagnosis and therapy of all kinds of vessel diseases.In this paper we mostly research vessel segmentation, vessel centerline extraction and the three dimensional representation of vessels in the three dimensional reconstruction .Vessel segmentation is the base of 3d reconstruction on Digital Subtraction Angiography images. In this paper we propose local thresholding approach of vessel segmentation based on knowledge for DSA images. The original DSA image is divided into several appropriate subimages according to a priori knowledge of the diameter of vessels. Then we apply local thresholding techniques to choose an optimal threshold for every subimage respectively. Finally an overall binarization of the original image is achieved by syncretizing the thresholded subimages. We do experiments on cerebral and hepatic DSA images, showing that our proposed methods yield satisfactory binary results efficiently.In the aspect of vessel centerline extraction, we propose multiscale vessel tracking using Gabor filters to extract and track vessels. The flexible frequency bands and enhancement effects of Gabor filters,are fully utilized to enhance centerlines of the blood vessels in various size. Than we choose a source and a goal in the enhancement response image to track the vessel by minimum cost path .This method should be able to cope with close proximity or crossing of vessels as well as with varying vessel widths including large stenoses and severe imaging artifacts.In the three dimensional representation of vessels, we firstly discuss the registration of two views and the skeleton reconstruction, than mainly introduce three dimensional representation of vessels based on the model of generalized cylinders. The second step includes acquirement of the three dimensional radius of vessels, smoothing centerlines and space orthogonal coordinate transformation. The proposed method is simple and efficient, which can show full three dimensional vessels.Finally, surface rendering is used to show the whole three dimensional vessels by VTK. This method is fast and show living result.更多还原