OPTIMIZATION OF PULSE ENVELOPES FOR MRI APPLICATIONS

MRI 应用的脉冲包络优化

• 批准号: 2100538
• 负责人: STEPHEN B PICKUP
• 金额: $ 11.07万
• 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 1999-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2100538
• 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.

磁共振作为临床诊断工具的应用， 近年来成为常见的地方。 其中绝大多数 应用于诊断成像技术。 的巨大优势 磁共振成像的最大优势在于， 在各种各样的参数，如流量，弛豫，质子密度， 或扩散。 新的成像技术不断发展， 惊人的速度。 高分辨率磁共振波谱是 也在临床环境中找到应用。 高分辨率 组织提取物、大量组织样品和体液的光谱具有 被用作疾病和药物滥用的筛查测试。 的 最具潜力的竞技场是 光谱学和成像技术。 体内光谱学可以 提供非代谢物中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没有发挥出来。 由于各种技术困难而实现。 所有这些技术都严重依赖于各种 合成和整形的射频脉冲 的响应特性 核自旋系统对这些脉冲的影响最终决定了 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改善 可以通过适当的脉冲包络设计来获得数据。 优化脉冲 包络线可以减少由于不完全重新聚焦在自旋上而造成的信号损失 回声和差的相位分散以及缩短回声时间， 空间位置和频率选择性。 在这里，我们建议实施脉冲包络的数值优化 设计 将详细研究优化技术， 以提供最有效的算法。 几个相对简单的目标 将在算法开发期间研究脉冲轮廓。 这些早期研究将涉及复合材料的设计， 幅度整形脉冲。 在脉冲设计完全优化后， 方法，将研究更复杂的脉冲。 完全优化 代码将被用来设计各种脉冲， 对脉冲的幅度和相位进行整形。 脉冲包络 将在特定的应用程序中实现， 设计了 将获得的数据质量与 将执行优化的和标准的脉冲包络。