Schei Thomas R, Barrett Steven, Jones Darrell, Krupski William
Electrical and Computer Engineering Department, University of Wyoming, Laramie, WY 82071, USA.
Biomed Sci Instrum. 2003;39:53-8.
Abdominal Aortic Aneurysms (AAA) are the 10th leading cause of death in older men. It is estimated that about 5% of men over 50 have AAA but the prevalence and risk of death due to rupture increase with age to estimated 10% prevalence and almost 1% of male deaths over the age of 65. AAA is defined as a focal dilation of the artery at least 50% larger than the normal diameter. If the defect is not surgically repaired prior to rupture, the mortality is about 80%. The role of clotted blood (thrombus) lining the walls of the AAA has been speculated to play a role in aneurysm expansion. Although aneurysm diameter is easily measured from a CT scan, accurately measuring the relative amount of clotted blood (thrombus load) cannot be readily done with a ruler. This paper presents a process to segment the relative thrombus area and aneurysmal area from CT images using computer algorithms. We have developed an image processing based technique, using MATLAB, to aid in the detection of a threatening AAA condition. This technique uses segmentation-based techniques to extract the desired data. The process of segmentation involves several steps to obtain desirable results. This algorithm uses primarily thresholding techniques, erosion, and dilation filters to segment the wall and determine the bounds of the aorta; then segmentation is done to enhance and isolate areas of interest.
腹主动脉瘤(AAA)是老年男性的第十大死因。据估计,50岁以上男性中约5%患有腹主动脉瘤,但随着年龄增长,其患病率以及因破裂导致的死亡风险都会增加,65岁以上男性的患病率估计为10%,因腹主动脉瘤破裂导致的死亡占男性死亡总数的近1%。腹主动脉瘤被定义为动脉的局限性扩张,其直径至少比正常直径大50%。如果在破裂前未进行手术修复,死亡率约为80%。有人推测,腹主动脉瘤壁上的凝血(血栓)在动脉瘤扩张中起作用。虽然通过CT扫描很容易测量动脉瘤直径,但用尺子无法轻易准确测量凝血的相对量(血栓负荷)。本文介绍了一种使用计算机算法从CT图像中分割相对血栓面积和动脉瘤面积的方法。我们利用MATLAB开发了一种基于图像处理的技术,以辅助检测具有威胁性的腹主动脉瘤情况。该技术使用基于分割的技术来提取所需数据。分割过程涉及几个步骤以获得理想结果。该算法主要使用阈值处理技术、腐蚀和膨胀滤波器来分割血管壁并确定主动脉边界;然后进行分割以增强和分离感兴趣区域。