Bio-dynamic monitoring, diagnosis and follow-up of Abdominal Aortic Aneurysms using optical imaging techniques

腹主动脉瘤（AAA）是腹主动脉的局部球囊样扩张。每10万人中至少有45人死于该病，这对老年人构成严重威胁。 目前，腹主动脉瘤腔内修复术（EVAR）是AAA最常见的治疗方法。这是一种微创治疗，其中将可扩张支架移植物（内假体）放置在主动脉内。内假体的主要问题是渗漏（内漏）和移位。由于内漏，动脉瘤囊在体循环血压下返回，这可能导致破裂。囊内的压力几乎无法测量。这种测量与其他指标（超声或CT扫描）一起，将极大地帮助确定是否需要再次干预。在过去，已经表明，由于心跳而在腹部上形成的机械波的测量可以是囊压力的间接指示，并且具有用作腹主动脉瘤腔内修复术之前和之后的诊断和监测信号的潜力。在申请人之一的先前预研究中，使用激光振动计测量腹部表面的振动。这一程序相当繁琐，而且没有对病人进行彻底的检查。在这个项目中，我们想研究几种光学技术来间接监测AAA囊压力的变化。特别是，数字图像相关（DIC）技术似乎很有前途的这种应用。DIC是一种基于立体视频图像的相当简单的技术，用于测量表面的3D运动（现在用于工程应用）。这样的光学技术尚未用于医学成像。诸如DIC的光学技术尚未被尝试用于监测医疗状况，尽管它们有可能为诸如AAA监测和诊断的医疗应用开辟一个全新的领域。该项目是机械工程学院和医学院之间的合作。

Abdominal aortic aneurisms (AAA) is a localized balloon-like dilation of the abdominal aorta. It accounts for the death of at least 45 individuals per 100,000 population and is a serious threat to aging people. Nowadays, endovascular aortic repair (EVAR) is the most common treatment for AAA. It is a minimally invasive treatment in which an expandable stent graft (endoprosthesis) is placed within the aorta. Major problems of endoprostheses are leakage (endoleak) and migration. Due to endoleaks, the aneurysm sac comes back under systemic blood pressure, which can cause rupture. The pressure inside the aneurism sac is nearly impossible to measure. Such a measurement, together with other indicators (ultrasound or CT scan), would greatly help determining the need for a reintervention. In the past, it has been shown that measurement of the mechanical wave forming on the abdomen due to the heart beat can be an indirect indication of the sac pressure and has the potential to be used as a diagnostics and monitoring signal before and after EVAR. In the previous pre-study of one of the applicants, a laser-vibrometer was used to measure the vibration of the abdomen surface. The procedure was rather cumbersome and also no thorough tests on patients were undertaken. In this project, we want to investigate several optical techniques to indirectly monitor the change of the AAA sac pressure. In particular, Digital Image Correlation (DIC) techniques seem promising for this application. DIC is a rather simple technique based on stereo video images to measure 3D motion of a surface (nowadays used in engineering applications). Such optical techniques are not yet used in medical imaging. Optical techniques such as DIC have not yet been tried to monitor medical conditions although they have the potential to open a whole new field for medical applications such as AAA monitoring and diagnosis. The project is a cooperation between the faculty of Mechanical Engineering and the School of medicine of TUM.