Feedback Control of the Nuclear Magnetization State (SGER Award)

本研究的目的是提高 现有核磁成像的性能， 光谱学方法应用的概念， 反馈控制 这些方法基于 观察核磁化的波动 由RF脉冲序列产生，并且在 成像，外加磁场梯度。 传统的成像和光谱技术 开环过程中，测量的 磁化状态用于优化脉冲 连续RF脉冲之间的参数。 这个项目特别关注对比度 增强磁共振成像。 一 自动调整脉冲的反馈策略 参数，以增强指定 化学物种正在发展。 控制设计是 在商用成像仪上进行了实验验证， 水和油的样品。 自适应控制算法 调整脉冲参数， 水和油磁化信号之间的关系是 最大化。 这项研究的意义是双重的。 首先介绍了成像和光谱学 社区的优势， 反馈 其次，它提供了一个基础， 考虑反馈概念的进一步应用， 核磁成像和光谱学。

The objective of this research is to improve the performance of existing nuclear magnetic imaging and spectroscopy methods of applying the concepts of feedback control. These methods are based on observing the fluctuations in nuclear magnetization produced by sequences of RF pulses and, in the case of imaging, applied magnetic field gradients. Conventional imaging and spectroscopy techniques are open-loop processes in that measurements of the magnetization state are used to optimize the pulse parameters between successive RF pulses. This project focuses specifically on contrast enhancement in magnetic resonance imaging. A feedback strategy that automatically adjusts pulse parameters to enhance the contrast between specified chemical species is developed. The control design is verified experimentally on a commercial imager using a sample of water and oil. An adaptive control algorithm tunes the pulse parameters so that the difference between the water and oil magnetization signals is maximized. The significance of this research is twofold. First, it introduces the imaging and spectroscopy communities to the advantages afforded by using feedback. Second, it provides a foundation on which to consider further applications of feedback concepts to nuclear magnetic imaging and spectroscopy.