Next-Generation fMRI with MB-SWIFT: Insights into the Origins of Contrast

采用 MB-SWIFT 的下一代功能磁共振成像：洞察对比度的起源

• 批准号: 10653089
• 负责人: SHALOM MICHAELI
• 金额: $ 53.41万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10653089
• 关键词: 3-Dimensional; Acoustics; Affect; Air; Anesthesia procedures; Animals; Behavioral; Blood flow; Brain; Brain Mapping; Cerebrovascular Circulation; Child; Clinical Research; Coiled Bodies; Consensus; Dependence; Detection; Devices; Dropout; Echo-Planar Imaging; Electrodes; Electrophysiology (science); Event; Fourier Transform; Frequencies; Functional Magnetic Resonance Imaging; Gases; Goals; Head; Human; Hypercapnia; Hyperoxia; Hypoxia; Image; Immobilization; Implant; Intervention; Investigation; Ions; Link; Loudness; Magnetic Resonance Imaging; Measures; Mediating; Membrane; Membrane Potentials; Metabolic; Methods; Morphologic artifacts; Motion; Movement; Neurons; Noise; Physiologic pulse; Physiological; Population; Predisposition; Proxy; Rattus; Relaxation; Research; Resolution; Rodent; Signal Transduction; Somatosensory Cortex; Specificity; Stimulus; Techniques; Testing; Time; Tissues; Vibrissae; awake; design; hemodynamics; insight; magnetic field; metallicity; neuroregulation; next generation; normoxia; novel; pre-clinical research; preservation; response; temporal measurement; tool; transmission process; virtual

ABSTRACT Our long term goal is to establish the newly developed zero echo time MRI pulse sequence entitled Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT) as the next-generation method of choice for artefact- free, quiet, high-resolution fMRI in humans, suitable for detecting neuronal activity via cellular mechanisms linked to electrical events that are intrinsically unattainable with standard readout sequences. MB-SWIFT has been already proven to offer remarkable advantages as compared to current fMRI techniques, since it is minimally impacted by susceptibility artefacts, has high tolerance for movement, and produces a nearly silent, continuous acoustic noise during acquisitions thanks to the use of slowly switching gradients. However, the origin of the functional contrast has remained elusive so far. Our general hypothesis is that MB-SWIFT functional signals closely reflect changes in local field potentials. We also advance the hypothesis that a non-negligible portion of the contrast may arise from T1 contrast mechanisms involving the pool of immobilized spins that are most likely sensitized to neuronal currents. Before undertaking a full-blown study that elucidates how relaxation mechanisms linked to membrane potentials and ions redistributions impact MB-SWIFT signals, we first need to validate that MB-SWIFT signals are sensitive proxies of neuronal activity, and determine whether they are substantially mediated by relaxation mechanisms not explained by blood flow or oxygenation changes. Ergo, the current proof- of-concept study in rodents will first establish to what extent MB-SWIFT signals reflect changes in neuronal activity under awake, physiological conditions by acquiring fMRI signals with MB-SWIFT and electrophysiological recording in somatosensory cortex during whisker stimulations of different duration and frequency. Then, we will evaluate to what extent MB-SWIFT signals are sensitive to changes in oxygenation levels and cerebral blood flow by conducting mechanistic studies during gas challenges, with different coil designs meant to isolate the inflow contribution, and with different magnetic fields, meant to verify the presence of T1-mechanisms of possible tissue origin. By achieving these aims we will gain pivotal insights into the substrates of the MB-SWIFT fMRI signals, and will reach initial milestones that will advance MB-SWIFT towards detection of neuronal currents, a goal that has been looked after for more than 20 years. In addition, the implications of the mechanistic studies will expand beyond MB-SWIFT, and they will be relevant to other MRI approaches with virtually zero echo time.

抽象的 我们的长期目标是建立新开发的零回波时间MRI脉冲序列标题为多波段 以傅立叶变换（MB-Swift）作为伪像的下一代选择方法 - 人类的免费，安静，高分辨率fMRI，适合通过连接的细胞机制检测神经元活动 对于标准读数序列本质上无法实现的电气事件。 MB-Swift一直以来 与当前的fMRI技术相比，已经被证明具有显着优势 受敏感性伪像的影响，对运动具有很高的耐受性，并产生了几乎沉默，连续的 由于使用缓慢的切换梯度，声音在采集期间的声音噪声。但是， 到目前为止，功能对比仍然难以捉摸。我们的总体假设是MB-Swift功能信号 密切反映了本地现场电位的变化。我们还提出了一个假设，即不可忽略的部分 对比可能是由涉及固定旋转池的T1对比机制引起的 对神经元电流敏感。在进行全面研究之前，阐明了如何放松机制 与膜电位和离子重新分配有关影响MB-Swift信号的链接，我们首先需要验证该信号 MB-Swift信号是神经元活性的敏感代理，并确定它们是否基本上是 由血流或氧合变化所解释的松弛机制介导的。 Ergo，当前的证明 - 在啮齿动物中的概念研究将首先建立在多大程度上反映神经元的变化的程度 在清醒下的活动，通过获得MB-Swift和电生理学的fMRI信号，生理条件 在不同持续时间和频率的晶须刺激期间记录体感皮质。然后，我们会的 评估MB-Swift信号在多大程度上对氧合水平和脑血的变化敏感 通过在气体挑战期间进行机械研究的流动，其不同的线圈设计旨在隔离 流入的贡献以及不同的磁场，旨在验证可能存在的T1机制 组织起源。通过实现这些目标，我们将获得对MB-Swift fMRI底物的关键见解 信号，并将达到最初的里程碑，将MB旋转前进到神经元电流的检测，一个 已经照顾了20多年的目标。另外，机械研究的含义 将扩展超出MB-SWIFT，它们将与其他ECHO时间为零的其他MRI方法相关。