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Sensitivity improvement of a nuclear magnetic resonance method to monitor a bioartificial pancreas.

机译：改善核磁共振方法以监测生物人工胰腺的敏感性。

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摘要

Non-invasive monitoring of implanted devices is becoming key in developing tissue-engineered structures intended to provide alternative or complementary treatment to people with organ or tissue impairment and/or loss. Bioartificial pancreases for the treatment of Type I diabetes are an example of such structures under development. Nuclear magnetic resonance (NMR) imaging and spectroscopy have already shown their potential for monitoring of these pancreatic substitutes and detecting their early marker of failure. However, the sensitivity of these NMR methods was limited. The studies presented in this dissertation investigate sensitivity improvement by developing inductively-coupled implantable RF coil systems at high magnetic field strength not only for 1H detection, but also for the detection of other informative, but less sensitive nuclei, such as 19F and 31P. An inductively-coupled implantable coil system was first developed for 1H detection to demonstrate the use on inductively-coupled implantable coil system at 11.1 T. Secondly, a development of a receive-only inductively-coupled implanted coil system was investigated to further improve 1H detection and increase localized spectroscopy performance. The feasibility of double frequency inductively-coupled implantable coil systems for simultaneous detection of 1H-31P and 1H- 19F were explored next, toward the development of a multiple frequency system. The requirements of these coil systems for a complete monitoring of a bioartificial construct were discussed. In parallel to the coil system developments, the inclusion of an RF coil within the implanted pancreatic construct was also studied to address the restrictions it imposed on the construct design. The results for 1H detection establish that large gains in signal-to-noise can be obtained with the use of inductively-coupled implanted coil systems when compared to the use of standard surface coils. This improvement provides a means to better analyze the structures of implanted bioartificial constructs and their changes over time on NMR images. It can also lower the limit of detection when spectroscopy is performed to detect choline NMR signal and allow for better quantitative analysis of bioartificial organ functions. A receive-only inductively-coupled implanted coil system was also successfully developed to further enhance localized spectroscopy since a more homogeneous NMR excitation magnetic field could be achieved with its use compared to the use of a transmit-receive system. 31P and 19F spectroscopy was also performed using single-frequency inductively-coupled implanted coil system for 31P detection to detect adenosinetriphosphate (ATP) and for 19F detection to detect perfluorocarbons (PFC). These results set the standards for the development of double-frequency inductively-coupled implantable coil systems. The feasibility of double-frequency inductively-coupled implantable coil system was assessed as well. Furthermore, data shows that a coil-construct assembly allowed insulin-producing cells to function and stay viable for extended periods of time in vitro. The return to normoglycemia in diabetic mice after coil-construct assembly implantation was also demonstrated while enhanced non-invasive monitoring of the implanted constructs was made possible using NMR methods.
机译：植入式设备的非侵入式监控正成为开发组织工程结构的关键，该结构旨在为患有器官或组织损伤和/或丧失的人提供替代或补充治疗。用于治疗I型糖尿病的生物人工胰腺是正在开发的这种结构的一个例子。核磁共振（NMR）成像和光谱学已经显示出它们在监测这些胰腺替代物和检测其早期失败标记方面的潜力。然而，这些NMR方法的灵敏度是有限的。本论文提出的研究通过开发感应耦合的可植入射频线圈系统在高磁场强度下的灵敏度提高，该系统不仅用于1H检测，而且还用于检测其他信息性但敏感性较低的核，例如19F和31P。首先开发了用于1H检测的电感耦合可植入线圈系统，以演示在11.1 T下用于电感耦合可植入线圈系统的应用。其次，研究了仅接收的电感耦合植入线圈系统的开发，以进一步改善1H检测。并提高局部光谱性能。接下来探讨了双频感应耦合植入式线圈系统用于同时检测1H-31P和1H-19F的可行性，以开发多频系统。讨论了这些线圈系统对生物人工构造的完整监视的要求。与线圈系统的发展并行，还研究了在植入的胰腺结构中包含RF线圈以解决其对结构设计的限制。 1H检测的结果表明，与使用标准表面线圈相比，使用电感耦合植入线圈系统可以获得较大的信噪比增益。这项改进提供了一种手段，可以在NMR图像上更好地分析植入的生物人工构造的结构及其随时间的变化。当执行光谱法检测胆碱NMR信号时，它还可以降低检测限，并可以对生物人工器官功能进行更好的定量分析。还成功开发了仅接收的电感耦合植入线圈系统，以进一步增强局部光谱，因为与使用发射-接收系统相比，使用它可以实现更均匀的NMR激发磁场。还使用单频感应耦合植入线圈系统执行31P和19F光谱，用于31P检测以检测三磷酸腺苷（ATP）和19F检测以检测全氟化碳（PFC）。这些结果为开发双频电感耦合可植入线圈系统奠定了标准。还评估了双频感应耦合可植入线圈系统的可行性。此外，数据显示，线圈构建体组装体使胰岛素产生细胞能够在体外长时间发挥功能并保持活力。还证实了糖尿病小鼠在线圈-结构组装体植入后恢复正常血糖，同时使用NMR方法可以增强对植入结构的非侵入性监测。

著录项

  • 作者

    Volland, Nelly A.;

  • 作者单位

    University of Florida.;

  • 授予单位 University of Florida.;
  • 学科 Engineering Biomedical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 214 p.
  • 总页数 214
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:25

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