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: 8239585
• 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/8239585
• 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）：该提案“用于梯度回声MRI的光谱空间RF脉冲”是一个MRI技术开发项目，用于使用3T时使用单个和多个发射器设计光谱空间射频（RF）激发。这些脉冲的设计旨在抑制不需要的脂质信号，降低敏感性伪像，并改善梯度回声MRI中的切片概况（B1+）均匀性。梯度回声应用，例如血氧水平依赖性（BOLD）大脑功能MRI（fMRI）由于磁敏感性变化而受到下部大脑区域的大信号空隙的困扰。此外，良好的梯度回声对比所需的高场使图像容易出现B1+不均匀性的强度变化。解决这些限制的方法对于利用MRI的全部好处来改善医疗保健和研究很重要。我们首先提出了一个或多个发射器上的频率选择性的2D光谱空间脉冲。这些脉冲可用于脂质抑制和取消平面易感梯度。易感性伪影校正假定平面梯度是异位频​​率的函数。获取场图以确定平面梯度的空间分布和非谐振的空间分布将测试此假设。然后，将使用并行传输方法利用地图的空间变化。下一种方法将是设计4D光谱空间脉冲，以便平行发射器开发激发，以同时校正平面敏感性伪影，面内发射器（B1+）不均匀性，并提供脂质抑制。然后，将将脉冲生成算法移植到图形编程单元（GPU）上以提高速度。脉冲将通过模拟，幻影和人类对照梯度回波成像研究进行测试和表征。脉冲的最终验证将使用易感加权成像（SWI），T2*映射和令人叹为观止的大胆fMRI实验的人类控制扫描。在开发本提案中描述的方法方面的成功将克服梯度回波MRI的主要局限性，这使得以前无法使用多种临床应用。此外，应用频谱空间脉冲和平行发射器对该建议是新颖的，并且代表了多维RF脉冲设计中的一大步。 公共卫生相关性：磁共振成像（MRI）是一种强大而非侵入性的技术，用于观察人体的解剖学，结构和功能。特别是梯度回声MRI对于包括大脑功能和结构成像在内的许多应用都有用。但是，足够的梯度回声对比所需的高场也以图像伪影的形式产生了挑战和障碍。该项目的目的是开发和验证一种技术系统，以纠正这些与现场相关的MRI伪像。拟议的研究最终将有助于降低MRI检查的成本和持续时间，并提供提高的诊断准确性。