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首页> 外文学位 >Developpement d'un systeme de tomographie par coherence optique pour la mesure de la compliance vasculaire cerebrale in-vivo.
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Developpement d'un systeme de tomographie par coherence optique pour la mesure de la compliance vasculaire cerebrale in-vivo.

机译：光学相干断层扫描系统的开发，用于测量体内脑血管顺应性。

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摘要

Optical imaging of the neurovascular network has been recently evolving at a rapid pace. Optical Coherence Tomography (OCT) has been used to produce high quality angiograms of cortical microvasculature in mice and rat. Through this technique, precise measurements of blood speed can be made without the use of invasive markers opening the door for studies of blood flow and neurovascular function. The current aim of research in the field is to develop imaging protocols and methods for studying specific neurovascular function.;OCT through it's ability to image the neurovascular network could offer an alternative way of measuring arteriolar compliance in-vivo. The aim of this work was therefore to develop and validate a technique for measuring compliance based on OCT measurements.;The OCT system developed in this work is based on a superluminescent diode emitting light in the near-infrared range at 870 nm. The system produces structural and flow images of the cerebral microvasculature in mice and rats. It has a maximum axial resolution of 9 mum, a penetration depth of 600 mum and a sensibility of 105 dB. The system was also able to produce accurate flow measurements between ∼ 10 and ∼ 100 nL/s when tested on a fantom and produced accurate volumetric maps of blood vessels with arterioles as small as 30 mum being imaged.;Along with the standard protocols for imaging volumes and slices through the vasculature, a novel reconstruction technique was developed. This technique uses electrocardiography information to produce sequences of OCT slices over one cardiac cycle. These sequences reveal the changes in blood speed and vessel area over that cycle. A simple arterial model then uses this novel information to produce an estimate of vessel compliance.;One such vascular function is arteriolar compliance. New hypothesis in the development of neurodegenerative diseases have revealed a link with vascular degeneration. Neurovascular regulation involves the supply of blood flow towards regions of neural activity. Blood supplies oxygen and nutriments to active neurons and improper supply of it can lead to neuronal dysfunction. Compliance is a characteristic of arteries describing their reaction to changes in pressure. It plays a key role in blood flow regulation and as such has been the subject of recent interest. The tools used for compliance evaluation require an extraction of the target vessel for ex-vivo characterization which eliminates any possibility of longitudinal studies on the same animal.;In order to test this new compliance evaluation method, a group study is presented. This study aims to reveal differences in arteriolar compliance between a group of normal mice and another one which spontaneously develops atherosclerotic lesions. Recent ex-vivo measurements have revealed that compliance of larger arteries in the brain is higher in the atherosclerotic group. The OCT study was able to corroborate this result in a non-invasive manner. Furthermore, OCT was able to estimate compliance in vessels that have thus far been too small for ex-vivo preparations. The same trend was observed for these smaller arterioles as that of the larger arteries where vessels of atherosclerotic mice would have a higher compliance then wild type vessels.;Following the group study, success in reaching the objectives of this work is evaluated. The system was found to offer satisfactory performance in terms of resolution, sensitivity and depth of field. Hardware and software improvements are suggested in order to achieve higher imaging quality. However, volumetric and cardiac reconstructions provide satisfactory results for compliance evaluation. Overall, every objective of this work is reached and OCT was successfully demonstrated to be a viable tool for evaluating cerebral arteriolar compliance in-vivo..
机译：最近，神经血管网络的光学成像发展迅速。光学相干断层扫描（OCT）已用于在小鼠和大鼠中产生皮质微脉管系统的高质量血管造影照片。通过这种技术，无需使用侵入性标记就可以研究血流和神经血管功能，就可以精确测量血流速度。该领域当前的研究目标是开发用于研究特定神经血管功能的成像方案和方法。OCT通过其对神经血管网络成像的能力可以提供一种测量体内小动脉顺应性的替代方法。因此，这项工作的目的是开发和验证一种基于OCT测量的合规性测量技术。该工作中开发的OCT系统基于在870 nm处发射近红外光的超发光二极管。该系统可在小鼠和大鼠中产生大脑微脉管系统的结构和流动图像。它的最大轴向分辨率为9微米，穿透深度为600微米，灵敏度为105 dB。当在扇形体上进行测试时，该系统还能够在约10至约100 nL / s之间产生准确的流量测量结果，并能生成精确的血管体积图，其中要成像的小动脉小至30毫米。通过血管的体积和切片，开发了一种新颖的重建技术。该技术使用心电图信息在一个心动周期内产生OCT切片序列。这些序列揭示了该周期内血流速度和血管面积的变化。然后，一个简单的动脉模型使用这一新颖的信息来估计血管的顺应性。;这样的血管功能之一就是小动脉的顺应性。神经退行性疾病发展的新假说揭示了与血管变性的联系。神经血管调节涉及向神经活动区域的血流供应。血液为活动的神经元提供氧气和营养，血液供应不当会导致神经元功能障碍。顺应性是描述动脉对压力变化反应的动脉特征。它在血流调节中起着关键作用，因此一直是最近的关注主题。用于依从性评估的工具需要提取目标血管以进行离体表征，从而消除了对同一只动物进行纵向研究的任何可能性。为了测试这种新的依从性评估方法，我们进行了小组研究。这项研究旨在揭示一组正常小鼠与另一只自发形成动脉粥样硬化病变的小鼠之间的小动脉顺应性差异。最近的离体测量显示，动脉粥样硬化组的大脑较大动脉的顺应性更高。 OCT研究能够以非侵入性的方式证实这一结果。此外，OCT能够估算迄今为止对于离体准备工作而言太小的船只的顺应性。对于这些较小的小动脉，与在动脉粥样硬化小鼠的血管中具有比野生型血管更高的顺应性的较大动脉相同的趋势被观察到。；在小组研究之后，评估了达到这项工作目标的成功率。发现该系统在分辨率，灵敏度和景深方面均提供令人满意的性能。为了获得更高的成像质量，建议对硬件和软件进行改进。但是，容积重建和心脏重建为依从性评估提供了令人满意的结果。总体而言，这项工作的每个目标均已实现，OCT已被成功证明是评估体内脑小动脉顺应性的可行工具。

著录项

  • 作者

    Baraghis, Edward.;

  • 作者单位

    Ecole Polytechnique, Montreal (Canada).;

  • 授予单位 Ecole Polytechnique, Montreal (Canada).;
  • 学科 Engineering Biomedical.;Physics Optics.
  • 学位 M.Appl.Sc.
  • 年度 2011
  • 页码 103 p.
  • 总页数 103
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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