Functional Brain Imaging with Oscillating Gradient DW-MRI

使用振荡梯度 DW-MRI 进行功能性脑成像

• 批准号: 8118692
• 负责人: John C Gore
• 金额: $ 19.5万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8118692
• 关键词: Affect; Animals; Attenuated; Blood Vessels; Blood flow; Brain; Brain Mapping; Brain imaging; Breathing; Caliber; Carbogen Breathing; Cell Size; Cell membrane; Cells; Cellular Structures; Characteristics; Clinical; Data; Derivation procedure; Detection; Development; Diffuse; Diffusion; Diffusion Magnetic Resonance Imaging; Dimensions; Event; Frequencies; Functional Magnetic Resonance Imaging; Human; Image; Imaging Techniques; Intracellular Space; Magnetic Resonance Imaging; Maps; Measurement; Measures; Methods; Motion; Neurologic; Neurons; Neurosciences Research; Organelles; Outcome Study; Physiologic pulse; Property; Rattus; Reporting; Research Personnel; Resolution; Series; Signal Transduction; Solutions; Specificity; Speed; Structure; Swelling; Techniques; Time; Tissues; Vasodilation; Water; Water Movements; Weight; Work; base; blood oxygen level dependent; cell dimension; cell water; design; hemodynamics; imaging modality; in vivo; magnetic field; migration; novel; optical imaging; oscillating gradient spin echo; relating to nervous system; response; somatosensory; time interval; water diffusion

DESCRIPTION (provided by applicant): This R21 application aims to develop and evaluate a novel magnetic resonance imaging (MRI) technique that has considerable potential for detection and mapping of neural activity in the brain with temporal resolution much greater than BOLD (blood oxygen level dependent) imaging or similar approaches that rely on detecting hemodynamic changes. The proposed technique builds on provocative claims by established investigators that MRI methods that are sensitive to the diffusion properties of tissue water (diffusion-weighted MRI, DW-MRI) can detect water shifts and axonal swelling that accompany neural firing, phenomena that are not unexpected and have also been reported by optical imaging, and which occur immediately proximal in space and time to neural electrical activity. However, the origins and robustness of these changes remain controversial and unsubstantiated, and clearly are not easy to detect using conventional DW-MRI. We have pioneered a novel diffusion imaging method that can be selectively sensitized to neural structures of a specific dimension, and which should be much more sensitive to changes in the dimensions of neural cells and water compartments. We therefore propose to explore its use as a method of detecting and mapping brain activity. Conventional DW-MRI methods based on the Pulsed Gradient Spin Echo (PGSE) method reflect the integrated effects of a variety of structural features, including those of relatively large spatial scale, greater than a nerve cell diameter, including nerve cell membranes. We have developed an alternative technique, oscillating gradient spin-echo (OGSE), which is capable of detecting restrictions to diffusion over much smaller spatial scales, which results in a high sensitivity specifically to the effects of changes in cell dimensions. Here we propose to establish whether OGSE imaging can reliably detect immediate diffusion changes induced by neural activity. We will apply optimized OGSE, conventional BOLD and PGSE methods, to image rat brain in vivo before and after administration of a pharmacological agent (PCP) known to elicit robust, slowly varying changes in brain activation, with/or without pre-treatment with an agent that blocks the effect (BINA). These slow-varying activations will allow derivation of quantitative estimates of microstructural changes within the tissue. We will also record BOLD, OGSE and PGSE images at high temporal resolution during forepaw stimulation administered in an event-related design, during normal breathing or while breathing carbogen. By comparing the time courses of these various image series we will be able to verify whether diffusion changes related to activation are detectable, whether they occur faster than vascular changes, and whether the OGSE data at high frequency reveal changes in tissue microstructure (neuronal swelling) that occurs faster and more proximal to the underlying electrical events than other methods. The potential outcome of these studies would be a method for mapping neural activation with high temporal and spatial resolution that could be used in diverse human and animal studies of the functional organization of the brain. PUBLIC HEALTH RELEVANCE: There are widespread applications, in both neuroscience research and clinical neurological and psychiatric practice, for imaging methods that can detect and map brain activity to delineate and understand the functional organization of the brain. Functional MRI is currently the single most powerful method available for obtaining information on brain activation with high spatial resolution, but unfortunately it relies on blood flow changes that have very slow temporal characteristics, so that very little information is obtainable about the timing of neural events at the speed of the underlying electrical activity. The MRI method proposed for development may in principle overcome this shortcoming and allows recordings of brain activity with both high spatial and temporal resolution. The work would also substantiate or refute claims by others about the ability of MRI to assess neural activity with high temporal resolution.

描述（由申请人提供）：该 R21 申请旨在开发和评估一种新型磁共振成像 (MRI) 技术，该技术在检测和绘制大脑神经活动图谱方面具有巨大潜力，其时间分辨率远大于 BOLD（血氧水平依赖） ）依赖于检测血流动力学变化的成像或类似方法。所提出的技术建立在知名研究人员的挑衅性主张之上，即对组织水的扩散特性敏感的 MRI 方法（扩散加权 MRI、DW-MRI）可以检测伴随神经放电的水转移和轴突肿胀，这些现象并不意外并且还通过光学成像进行了报道，并且其在空间和时间上紧邻神经电活动发生。然而，这些变化的起源和稳健性仍然存在争议且未经证实，并且显然使用传统的 DW-MRI 不容易检测到。我们开创了一种新颖的扩散成像方法，可以选择性地对特定维度的神经结构敏感，并且对神经细胞和水室的维度变化更加敏感。因此，我们建议探索其作为检测和绘制大脑活动图的方法的用途。 传统的基于脉冲梯度自旋回波（PGSE）方法的DW-MRI方法反映了多种结构特征的综合影响，包括相对较大的空间尺度、大于神经细胞直径（包括神经细胞膜）的结构特征。我们开发了一种替代技术，振荡梯度自旋回波（OGSE），它能够检测更小的空间尺度上的扩散限制，从而对细胞尺寸变化的影响具有很高的灵敏度。在这里，我们建议确定 OGSE 成像是否能够可靠地检测神经活动引起的即时扩散变化。我们将应用优化的 OGSE、传统的 BOLD 和 PGSE 方法，在施用药物 (PCP) 之前和之后对大鼠大脑进行体内成像，该药物已知会引起大脑激活的强烈、缓慢变化的变化，有/或没有预先治疗阻断效应的试剂（BINA）。这些缓慢变化的激活将允许对组织内的微观结构变化进行定量估计。我们还将在以事件相关设计进行前爪刺激期间、正常呼吸期间或呼吸卡波根时以高时间分辨率记录 BOLD、OGSE 和 PGSE 图像。通过比较这些不同图像系列的时间进程，我们将能够验证与激活相关的扩散变化是否可检测到，它们是否比血管变化发生得更快，以及高频 OGSE 数据是否揭示了组织微观结构的变化（神经元肿胀）与其他方法相比，这种方法发生得更快、更接近潜在的电事件。这些研究的潜在结果将是一种以高时间和空间分辨率绘制神经激活图谱的方法，可用于大脑功能组织的各种人类和动物研究。 公共健康相关性：在神经科学研究以及临床神经学和精神病学实践中，成像方法可以检测和绘制大脑活动图，以描绘和理解大脑的功能组织，具有广泛的应用。功能性 MRI 是目前可用于获取高空间分辨率的大脑激活信息的最强大的方法，但不幸的是，它依赖于具有非常缓慢的时间特征的血流变化，因此获得的关于神经事件时间的信息非常少。潜在电活动的速度。提出开发的 MRI 方法原则上可以克服这一缺点，并允许以高空间和时间分辨率记录大脑活动。这项工作还将证实或反驳其他人关于 MRI 能够以高时间分辨率评估神经活动的能力的说法。