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首页> 外文学位 >From surface loop coil to dipole antenna: Radiofrequency coil designs inspired by Ideal Current Patterns for high-sensitivity MRI at high magnetic field strength.
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From surface loop coil to dipole antenna: Radiofrequency coil designs inspired by Ideal Current Patterns for high-sensitivity MRI at high magnetic field strength.

机译：从表面环形线圈到偶极天线：受理想电流模式启发的射频线圈设计，可在高磁场强度下实现高灵敏度MRI。

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摘要

Remarkable progress in radiofrequency (RF) coil design has been achieved over the last two decades, improving the performance of many magnetic resonance imaging (MRI) techniques, and facilitating numerous clinical and scientific applications. However, a rational general framework for optimizing RF coil design is still missing, especially at ultra-high field strength (UHF), where optimal coil configurations have yet to be determined. Recent studies on ultimate intrinsic signal-to-noise ratio (UISNR) -- that is, the maximum signal-to-noise ratio compatible with electrodynamic principles -- have established stepping stones towards such a framework. In particular, the ideal current patterns that achieve UISNR in a particular geometry may be used as a guide to optimize the pattern of conductors in a prospective RF coil design.;As an alternative to loop coils, electric dipole antennas have recently been introduced for use in MR signal generation and reception, and they have seen increasing use in UHF applications. As the field strength, and the corresponding operating frequency, of MR scanners increases, contributions of axially-directed currents to UISNR in the center of cylindrical objects become increasingly dominant, which suggests that properly configured dipole antennas should be strong performers at UHF. However, while various particular dipole antenna configurations have been proposed in the literature, optimality has yet to be demonstrated. Additionally, connections between potentially complex ideal current patterns and practical coil designs are only beginning to emerge.;The contributions presented in this dissertation demonstrate the utility of dipole antennas and explore their optimization in practice. A coil design framework for SNR optimization is introduced, which provides useful interpretations of the ideal current patterns for UISNR. Although most simulations and experiments described in the dissertation were carried out at 7 Tesla, the underlying design philosophy can be applied to any field strength, and could be especially relevant for even higher field strengths and operating frequencies.
机译：在过去的二十年中，射频（RF）线圈设计取得了显着进展，改善了许多磁共振成像（MRI）技术的性能，并促进了许多临床和科学应用。但是，仍然缺少用于优化RF线圈设计的合理通用框架，特别是在超高场强（UHF）领域，尚未确定最佳的线圈配置。最近对最终固有固有信噪比（UISNR）的研究-即与电动原理兼容的最大信噪比-为建立这样的框架奠定了基础。特别是，在特定几何形状中实现UISNR的理想电流模式可以用作指导，以优化预期RF线圈设计中的导体模式。;作为环形线圈的替代方法，最近引入了电偶极天线以供使用在MR信号的产生和接收中，它们已经在UHF应用中得到越来越多的使用。随着MR扫描仪的场强和相应的工作频率的增加，轴向电流对圆柱形物体中心的UISNR的贡献变得越来越占主导地位，这表明正确配置的偶极天线在UHF上应表现出色。然而，尽管在文献中已经提出了各种特定的偶极天线配置，但是尚未证明最优性。此外，潜在的复杂理想电流模式与实际线圈设计之间的联系才刚刚开始出现。本文的贡献证明了偶极天线的实用性，并在实践中对其进行了优化。介绍了用于SNR优化的线圈设计框架，该框架为UISNR的理想电流模式提供了有用的解释。尽管论文中描述的大多数模拟和实验都是在7 Tesla上进行的，但其基本的设计理念仍可应用于任何磁场强度，甚至对于更高的磁场强度和工作频率也可能特别重要。

著录项

  • 作者

    Chen, Gang.;

  • 作者单位

    New York University.;

  • 授予单位 New York University.;
  • 学科 Medical imaging.
  • 学位 Ph.D.
  • 年度 2017
  • 页码 193 p.
  • 总页数 193
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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