MRI Parallel Excitation for Neuroimaging Applications

描述（由申请人提供）：提出生物工程研究合作伙伴关系（PAR-06-459），用于开发平行激励技术，以改善额叶下皮层的功能磁共振成像（fMRI）研究。这个项目的动机是需要消除大的信号空洞和图像失真，这是由脑组织和鼻窦空气之间的磁化率差异引起的。这些伪影在功能磁共振成像中是普遍存在的，特别是对于许多下脑结构，包括眶额皮质（OFC）、下颞叶和内侧颞叶以及脑干结构。大脑的这些部分与神经退行性疾病、癫痫、精神疾病和酒精/药物滥用障碍有关。目前许多去除这些畸变的技术在时间分辨率或检测激活的灵敏度方面都有很大的成本。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发脉冲持续时间长方面受到限制。并行激励是一种新技术，通过使用多个独立的激励通道，可以在MRI中激发特定模式或更均匀的模式时具有更大的灵活性。对于多维激励模式，例如在fMRI中用于消除下脑区域信号丢失伪影的那些，平行激励应该允许更短的脉冲，并提供更完整的校正。该项目是一个独特的多学科项目，涉及并行激励脉冲设计、并行激励硬件、系统集成以及在患者研究中的应用。该项目将由一个多学科研究小组领导：该项目的首席研究人员是Douglas Noll （PI；系统集成和软件，验证），Jeffrey Fessler（脉冲优化）和Stephen Taylor（患者研究）；所有这些都来自密歇根大学和来自德克萨斯A&M大学的Steven Wright（共同负责人；硬件，系统集成）。该项目为并行激励脉冲设计提供了新的优化策略，为驱动并行发射阵列提供了独特的电流源技术，并对OFC的功能进行了重要的科学研究。总之，这些方法为功能性MRI带来了有价值的新方法，这些方法能够以与其他结构相同的灵敏度探测大脑下部结构，这将有助于研究各种神经精神疾病。本文所开发的并行激励技术也将推动MRI技术在高磁场下的激励不均匀性校正以及多维激励在MRI中的许多其他应用的发展。

DESCRIPTION (provided by applicant): 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.