MRI Parallel Excitation for Neuroimaging Applications

生物工程研究伙伴关系（PAR-06-459）提出了发展并行激发 技术，以改善功能性磁共振成像（fMRI）研究在下额叶皮层。 该项目的动机是需要消除大的信号空洞和图像失真所造成的 脑组织和鼻窦中空气之间的磁化率差异。这些文物是 在功能磁共振成像中普遍存在，特别是对于许多下脑结构，包括眶额皮质（OFC）， 下颞叶和中颞叶以及脑干结构。大脑的这些部分与 神经变性疾病、癫痫、精神病和酒精/药物滥用疾病。 去除这些失真的许多当前技术在时间分辨率或分辨率方面具有很大的成本。 检测激活的灵敏度。我们的团队开创了减少这些伪影的方法， 包括多维选择性激发，这是一种很有前途的技术，但目前在 校正程度和激励脉冲的长持续时间。 并行激励是一种新技术，它将允许更大的灵活性，在激发特定的模式或更多 通过使用多个独立的激励通道在MRI中实现均匀的模式。用于多维 激发模式，例如用于消除功能磁共振成像中大脑下部区域的信号丢失伪影的那些， 并行激励应允许更短的脉冲并提供更完全的校正。这个项目是独一无二的 多学科的，因为它涉及并行激励脉冲设计，并行激励硬件， 系统集成和应用于患者研究。该项目将由一个多学科的 研究者组：本项目的首席研究者是道格拉斯诺尔（PI;系统集成和 软件，验证），Jeffrey Fessler（脉冲优化）和Stephen Taylor（患者研究）;均来自 Univ.和Steven Wright（Co-Pi;硬件，系统集成）。 该方案为并联激励脉冲设计提供了新颖的优化策略，独特的电流源 驱动并行发射阵列的技术，以及对 在OFC。总之，这些方法导致有价值的新方法的功能磁共振成像， 探测大脑下部结构的灵敏度与其他结构相同，这将有助于研究 各种神经精神疾病这里开发的并联励磁技术也将向前推进 磁共振成像技术的一般状态，用于校正在高磁场下的激励不均匀性， 多维激励在MRI中的许多其它应用。

A Bioengineering Research Partnership (PAR-06-459) is proposed for the development of parallel excitation technology to improve functional magnetic resonance imaging (fMRI) studies in the inferior frontal cortex. This project is motivated by the need to eliminate large signal voids and image distortions caused by magnetic susceptibility differences between brain tissue and air in the nasal sinuses. These artifacts are ubiquitous in fMRI, especially for many inferior brain structures including the orbitofrontal cortex (OFC), inferior and medial temporal lobes, and brain stem structures. These parts of the brain have been implicated in neurodegenerative disorders, epilepsy, psychiatric conditions and alcohol/substance abuse disorders. Many current techniques to remove these distortions have a large cost in terms of temporal resolution or sensitivity for detection of activation. Our group has pioneered methods for reducing these artifacts, including multidimensional selective excitation, a technique that is promising, but is currently limited in the degree of correction and by the long duration of the excitation pulses. Parallel excitation is a new technology that will allow for greater flexibility in exciting specific patterns or more uniform patterns in MRI through the use of multiple independent excitation channels. For multidimensional excitation patterns, such as those used to eliminate the signal-loss artifacts in inferior brain regions in fMRI, parallel excitation should allow shorter pulses and offer more complete correction. This project is uniquely multidisciplinary in that it involves advances in parallel excitation pulse design, parallel excitation hardware, system integration, and application to studies of patients. This project will be lead by a multidisciplinary group of investigators: the Lead Investigators for this project are Douglas Noll (PI;System Integration and Software, Validation), Jeffrey Fessler (Pulse Optimization), and Stephen Taylor (Patient Studies); all from Univ. of Michigan and Steven Wright (Co-Pi; Hardware, System Integration) from Texas A&M University. This project offers novel optimization strategies to parallel excitation pulse design, unique current source technologies for driving the parallel transmit array, and important scientific investigation into the functioning of the OFC. Together, these approaches lead to valuable new methods for functional MRI that are capable of probing inferior brain structures with sensitivity equal to other structures, which will aid in the study of a variety of neuropsychiatric disorders. The parallel excitation technology developed here will also advance the general state of MRI technology for correction of excitation inhomogeneity at high magnetic fields and for many other application of multidimensional excitation in MRI.