Spectral Spatial RF Pulses for Gradient Echo fMRI

用于梯度回波 fMRI 的频谱空间射频脉冲

• 批准号: 8055365
• 负责人: Victor Andrew Stenger
• 金额: $ 26.61万
• 依托单位: UNIVERSITY OF HAWAII AT MANOA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8055365
• 关键词: Address; Algorithms; Anatomy; Brain; Brain region; Data; Development; Four-dimensional; Frequencies; Functional Magnetic Resonance Imaging; Generations; Goals; Health Services Research; Human; Human body; Image; Imaging technology; Inferior; Lipids; Magnetic Resonance Imaging; Magnetism; Maps; Methods; Morphologic artifacts; Physiologic pulse; Plague; Predisposition; Process; Radio; Recovery; Research; Scanning; Signal Transduction; Slice; Spatial Distribution; Speed; Structure; System; Techniques; Testing; Time; Translating; Validation; Variant; Weight; blood oxygen level dependent; clinical application; cost; design; diagnostic accuracy; improved; novel; programs; prototype; public health relevance; research study; simulation; success; technology development; transmission process; two-dimensional

DESCRIPTION (provided by applicant): This proposal "Spectral-Spatial RF Pulses for Gradient Echo MRI" is an MRI technology development project to design spectral-spatial Radio Frequency (RF) excitations using single and multiple transmitters at 3T. These pulses will be designed with the goal of suppressing unwanted lipid signal, reducing susceptibility artifacts, and improving slice profile (B1+) uniformity in gradient echo MRI. Gradient echo applications such as blood oxygen level dependent (BOLD) brain functional MRI (fMRI) are plagued by large signal voids in the inferior brain regions due to magnetic susceptibility variations. Furthermore, the high fields required for good gradient echo contrast make the images prone to intensity variations from B1+ inhomogeneity. Methods that address these limitations are important to exploit the full benefits of MRI for improved health care and research. We first propose 2D spectral spatial pulses for slice and frequency selectivity on one or multiple transmitters. These pulses can be used for both lipid suppression and the cancellation of the through-plane susceptibility gradient. The susceptibility artifact correction assumes that the through-plane gradient is a function of off- resonance frequency. Acquiring field maps to determine the spatial distribution of through-plane gradients and off-resonance will test this assumption. The spatial variations of the maps will then be exploited using parallel transmission methods. The next approach will be to design 4D spectral-spatial pulses for parallel transmitters to develop excitations that simultaneously correct for through-plane susceptibility artifact, in-plane transmitter (B1+) inhomogeneity, and provide lipid suppression. The pulse generation algorithms will then be ported for use on graphics programming units (GPUs) for increased speed. The pulses will be tested and characterized with simulations and phantom and human control gradient echo imaging studies. Final validation of the pulses will use human control scanning with susceptibility weighted imaging (SWI), T2* mapping, and breath-holding BOLD fMRI experiments. Success in developing the methods described in this proposal will overcome major limitations in gradient echo MRI, making feasible a broad range of clinical applications not previously possible. Furthermore, the application spectral-spatial pulses and parallel transmitters is novel to this proposal and represent a big step forward in multi-dimensional RF pulse design. PUBLIC HEALTH RELEVANCE: Magnetic resonance imaging (MRI) is a powerful and non-invasive technique for observing anatomy, structure, and function in the human body. In particular gradient echo MRI is useful for a number of applications including brain functional and structural imaging. However, the high fields required for adequate gradient echo contrast also produce challenges and obstacles in the form of image artifacts. The goal of this project is to develop and validate a system of techniques to correct for these field related MRI artifacts. The proposed research will ultimately aid in reducing the cost and duration of MRI examinations and provide improved diagnostic accuracy.

描述（由申请人提供）：本提案“用于梯度回波 MRI 的频谱空间 RF 脉冲”是一个 MRI 技术开发项目，旨在使用 3T 的单个和多个发射器设计频谱空间射频 (RF) 激励。这些脉冲的设计目标是抑制不需要的脂质信号、减少磁化率伪影并改善梯度回波 MRI 中的切片剖面 (B1+) 均匀性。由于磁化率变化，血氧水平依赖 (BOLD) 脑功能 MRI (fMRI) 等梯度回波应用受到下脑区域大信号空洞的困扰。此外，良好的梯度回波对比度所需的高场使得图像容易因 B1+ 不均匀性而发生强度变化。解决这些局限性的方法对于充分利用 MRI 的优势来改善医疗保健和研究非常重要。我们首先提出了二维频谱空间脉冲，用于一个或多个发射器上的切片和频率选择性。这些脉冲可用于脂质抑制和穿过平面磁化率梯度的消除。磁化率伪影校正假设穿过平面的梯度是非共振频率的函数。获取场图以确定平面梯度和失共振的空间分布将测试这一假设。然后将使用并行传输方法来利用地图的空间变化。下一个方法是为并行发射器设计 4D 光谱空间脉冲，以开发同时校正平面磁化率伪影、面内发射器 (B1+) 不均匀性的激励，并提供脂质抑制。然后，脉冲生成算法将被移植到图形编程单元 (GPU) 上使用，以提高速度。将通过模拟、体模和人类控制梯度回波成像研究来测试和表征脉冲。脉冲的最终验证将使用具有磁敏感加权成像 (SWI)、T2* 映射和屏气 BOLD fMRI 实验的人体控制扫描。成功开发本提案中描述的方法将克服梯度回波 MRI 的主要限制，使以前不可能的广泛临床应用变得可行。此外，频谱空间脉冲和并行发射器的应用对于该提案来说是新颖的，代表着多维射频脉冲设计向前迈出了一大步。 公共健康相关性：磁共振成像 (MRI) 是一种强大的非侵入性技术，用于观察人体的解剖结构、结构和功能。特别是梯度回波 MRI 可用于许多应用，包括脑功能和结构成像。然而，足够的梯度回波对比度所需的高场也会以图像伪影的形式产生挑战和障碍。该项目的目标是开发和验证一个技术系统来纠正这些与现场相关的 MRI 伪影。拟议的研究最终将有助于降低 MRI 检查的成本和持续时间，并提高诊断准确性。