OPTIMIZATION OF PULSE ENVELOPES FOR MRI APPLICATIONS

MRI 应用的脉冲包络优化

• 批准号: 2654113
• 负责人: STEPHEN B PICKUP
• 金额: $ 9.04万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-02-01 至 1999-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2654113
• 关键词: clinical biomedical equipment; diagnosis design /evaluation; diagnostic tests; magnetic resonance imaging; technology /technique development

The application of magnetic resonance as a clinical diagnostic tool has become common place in recent years. The large majority of these applications are in diagnostic imaging techniques. The great advantage of magnetic resonance imaging is that the contrast can be made to depend on a wide variety of parameters such as flow, relaxation, proton density, or diffusion. New imaging techniques continue to develop at an astonishing rate. High resolution magnetic resonance spectroscopy is also finding applications in the clinical environment. High resolution spectra of tissue extracts, bulk tissue samples and bodily fluids have been used as screening tests for disease as well as drug abuse. The arena which shows the greatest unrealized potential is the combination of spectroscopic and imaging techniques. In vivo spectroscopy could provide concentration information for a variety metabolites in a non destructive, non invasive manner. This potential has gone largely un realized due to a variety of technical difficulties. All of these techniques rely heavily on the implementation of a variety of composite and shaped RF pulses. The response characteristic of the nuclear spin system to these pulses ultimately determines the quality of the data attained in these studies. Recent studies suggest that considerable improvements in the quality of clinical magnetic resonance data can be attained by proper pulse envelope design. Optimized pulse envelopes could reduce signal loss due to incomplete refocusing on spin echis and poor phase dispersion as well as shorten echo times, improves spatial location, and frequency selectivity. Here we propose implementing numerical optimization in pulse envelop design. The optimization techniques will be studied in detail in order to provide a most efficient algorithm. Several relatively simple target pulse profiles will be investigated during the algorithm development. These early investigations will involve the design of composite and magnitude shaped pulses. Upon full optimization of the pulse design method, more complex pulses will be investigated. The fully optimized codes will be used to design a variety of pulses in which both the magnitude and the phase of the pulse are shaped. The pulse envelopes will be implemented in the particular applications for which they were designed. A comparison of the quality of the data attained with the optimized and standard pulse envelopes will be performed.

磁共振作为一种临床诊断工具的应用 近年来变得司空见惯。其中的绝大多数 应用领域是诊断成像技术。最大的优势 磁共振成像的一个特点是，对比度可以依赖于 基于各种各样的参数，例如流动、松弛、质子密度、 或者扩散。新的成像技术继续以惊人的速度发展 惊人的速度。高分辨率磁共振波谱是 在临床环境中也找到了应用。高分辨率 组织提取物、大块组织样本和体液的光谱 被用作疾病和药物滥用的筛查测试。这个 显示出最大未实现潜力的竞技场是组合 光谱和成像技术。体内光谱学可以 提供各种代谢物的浓度信息 破坏性的、非侵入性的方式。这种潜力在很大程度上已经消失了 由于各种技术困难而实现。 所有这些技术在很大程度上依赖于各种 复合和整形的射频脉冲。的响应特性。 核自旋系统对这些脉冲的质量最终决定 在这些研究中获得的数据。最近的研究表明 临床磁共振质量的显著提高 通过适当的脉冲包络设计可以获得数据。优化脉冲 包络可以减少因自旋未完全重聚焦而造成的信号损失 Echis和较差的相位色散以及缩短的回声时间，改进了 空间位置和频率选择性。 在这里，我们提出在脉冲包络中实现数值优化 设计。优化技术将按顺序进行详细的研究 以提供最高效的算法。几个相对简单的目标 脉冲分布将在算法开发期间进行调查。 这些早期调查将涉及复合材料的设计和 大小形状的脉冲。在充分优化脉冲设计的基础上 方法，将研究更复杂的脉冲。全面优化的 代码将被用来设计各种脉冲，其中 对脉冲的幅度和相位进行整形。脉搏包络 将在它们所针对的特定应用程序中实现 都是设计好的。将所获得的数据质量与 将执行优化的和标准的脉冲包络。