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首页> 外文学位 >Etude des parametres physiques en vue d'applications medicales de l'actionnement magnetique de dispositifs medicaux par un systeme d'imagerie par resonance magnetique.
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Etude des parametres physiques en vue d'applications medicales de l'actionnement magnetique de dispositifs medicaux par un systeme d'imagerie par resonance magnetique.

机译：通过磁共振成像系统研究医疗设备的磁驱动医疗设备的物理参数。

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摘要

An actuation and control method for medical devices based on the magnetic gradient coils of a Magnetic Resonance Imaging (MRI) was proposed for the first time in 2002 by NanoRobotics Laboratory [1].;In light of these results, the aim of this thesis is the study of the physical parameters involved in the development of a first medical application: the steering of magnetic particles in MRI in the context of drug targeting. It was demonstrated that an MRI system equipped with a set of magnetic gradient coils with enhanced amplitude was able to apply a high enough actuation force to act upon magnetic microparticles suspended in a liquid.;General rules for MRI actuation were identified. First of all, increasing the amplitude of the main magnetic field of the MRI leads to the increase of the actuation force amplitude only until the ferromagnetic body reaches its saturation magnetization. Moreover, soft ferromagnetic bodies appear to be better candidates for MRI based magnetic actuation because they can reach high saturation magnetizations. Magnetic gradient amplitude appears as a foremost factor to increase the amplitude of the magnetic force. Clinical MRI systems do not provide gradients with high enough amplitude for the applications studied here. Theoretical models developed in this thesis predict that a one order of magnitude increase in gradient amplitude would be required. Implementing actuation dedicated gradient coils is therefore suggested. Finally, a larger ferromagnetic body will lead to higher magnetophoretic velocities for magnetic particles.;In the context of magnetic microparticle targeting for cancer treatment through embolisation, the scaling laws bridging from the preliminary works with millimeter sized beads to magnetic microparticles suspensions were studied. Magnetic microparticles suspensions injected through branching channels were guided in MRI under the influence of magnetic gradients. The goal of these experiments was to maximize the amount of particles flowing through one of the outlets of the channel. The outcome of the experiments was quantified using an optical set-up as well as by analyzing the suspension at each outlet of the channels. The most important parameters that were identified are the magnetic force amplitude, the interactions and aggregation between magnetic particles of the suspension, the size, geometry and density of the particles or aggregates driven, the dimensions of the channel and the intensity of the flow. Mathematical models based on analyses of particle trajectories and on non dimensionalization of the experimental parameters were proposed. The model predicts steering efficiencies in the order of what was recorded experimentally. Nevertheless, some parameters that remain to be quantified more precisely like the effects of magnetic aggregation and friction forces cause discrepancies between theoretical and experimental data. Despite these differences, the knowledge gained in the field of magnetic suspension steering appears to be sufficient to envision in vivo experiments lead in parallel with improving the theoretical predictions. Hence, an experimental set-up and an experimental protocol are being designed to adapt the steering methods to interventional procedures and animal subjects.;The work undertaken in the present thesis began in the context of demonstrating the concept of automatic navigation of a magnetic bead in vivo. From the point of view of actuation, models and experimental data correlate. A maximum velocity of 13cm/s was measured for a 1.5mm diameter chrome steel bead in the carotid artery of a living swine. The bead was under the influence of magnetic gradients applied by a clinical MRI system without any hardware modification.;Finally, the same principles used for microparticle steering can be applied for magnetic catheter navigation. Hence, on the side of the main subject of this thesis, the deflection of magnetic catheters by MRI was also studied as a second medical application. Using magnetic catheter and guide wires could facilitate the placement of medical instruments and accelerate medical procedures. The recorded deflections are lower than the ones measured with other magnetic guidance systems. The parameters and performances obtained are functions of the amplitude of the applied magnetic force and material strength properties of the catheters or guide wires. Hence, deflection could be enhanced by adapting the mechanical properties of the devices, by increasing the amplitude of the magnetic gradient or the volume and magnetization of the magnetic tip. These latter results are the object of an upcoming patent application. Hence, the paper relating them could not be submitted prior to the submission date of this thesis. For this reason, this paper's manuscript is presented as an annex of the present document.
机译：NanoRobotics Laboratory [1]于2002年首次提出了一种基于磁共振成像（MRI）磁梯度线圈的医疗设备致动和控制方法[1]。鉴于这些结果，本论文的目的是：第一个医学应用开发过程中涉及的物理参数的研究：在靶向药物的情况下在MRI中控制磁性粒子。事实证明，配备有一组振幅增大的磁性梯度线圈的MRI系统能够施加足够高的致动力，以作用于悬浮在液体中的磁性微粒。;确定了MRI致动的一般规则。首先，仅在铁磁性体达到其饱和磁化强度之前，增大MRI主磁场的振幅会导致致动力振幅的增大。而且，软铁磁体似乎更适合用于基于MRI的磁驱动，因为它们可以达到高饱和磁化强度。磁性梯度振幅是增加磁力振幅的最重要因素。临床MRI系统无法为此处研究的应用提供足够高幅度的梯度。本文开发的理论模型预测，梯度振幅将需要增加一个数量级。因此建议实施致动专用梯度线圈。最后，更大的铁磁体将导致更高的磁性粒子磁泳速度。在通过栓塞法将磁性微粒靶向用于癌症治疗的背景下，研究了将定标规律从毫米大小的磁珠的初步工作桥接到磁性微粒悬浮液的过程。通过分支通道注入的磁性微粒悬浮液在磁梯度的影响下在MRI中被引导。这些实验的目的是使流过通道出口之一的颗粒量最大化。使用光学装置以及通过分析通道的每个出口处的悬浮液来量化实验的结果。确定的最重要的参数是磁力振幅，悬浮液磁性颗粒之间的相互作用和聚集，所驱动的颗粒或聚集体的大小，几何形状和密度，通道的尺寸以及流动强度。提出了基于粒子轨迹分析和实验参数无量纲化的数学模型。该模型以实验记录的顺序预测转向效率。尽管如此，某些参数还有待更精确地量化，例如磁聚集和摩擦力的影响，导致理论数据与实验数据之间出现差异。尽管存在这些差异，但在磁悬浮转向领域获得的知识似乎足以预见体内实验的开展与改进理论预测的同时。因此，正在设计实验装置和实验方案，以使操纵方法适应于介入程序和动物受试者。本论文中的工作是在演示磁珠自动导航概念的背景下开始的。体内。从致动的角度来看，模型和实验数据是相关的。在活猪的颈动脉中测得的直径为1.5mm的铬钢珠的最大速度为13cm / s。磁珠受临床MRI系统施加的磁梯度的影响，无需任何硬件修改。最后，用于微粒操纵的相同原理也可以应用于磁导管导航。因此，在本论文的主要主题方面，还研究了通过MRI对磁性导管的偏转作为第二医学应用。使用磁性导管和导丝可以促进医疗器械的放置并加快医疗程序。记录的挠度低于其他磁导系统测得的挠度。获得的参数和性能是所施加的磁力的振幅和导管或导丝的材料强度特性的函数。因此，可以通过调整装置的机械性能，增加磁梯度的幅度或增大磁头的体积和磁化强度来提高挠度。后一种结果是即将提出的专利申请的目的。因此，与它们相关的论文不能在本论文的提交日期之前提交。因此，本文的稿件作为本文件的附件提供。

著录项

  • 作者

    Mathieu, Jean-Baptiste.;

  • 作者单位

    Ecole Polytechnique, Montreal (Canada).;

  • 授予单位 Ecole Polytechnique, Montreal (Canada).;
  • 学科 Engineering Biomedical.;Physics Electricity and Magnetism.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 184 p.
  • 总页数 184
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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