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: 8287543
• 负责人: John C Gore
• 金额: $ 23.4万
• 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 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8287543
• 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.

描述（由申请人提供）：此R21应用旨在开发和评估一种新型的磁共振成像（MRI）技术，该技术具有相当大的检测和映射大脑中神经活动的潜力，其时间分辨率大于大胆（血氧水平依赖性）成像或依赖于检测血液动力学变化的类似方法。所提出的技术基于既定研究者的挑衅性主张，即对组织水的扩散特性敏感的MRI方法（扩散 - 偏射的MRI，DW-MRI）可以检测水移和轴突膨胀，这些轴突肿胀并非出乎意料，并且在光学上也是如此的现象，这些现象也不是出乎意料的。但是，这些变化的起源和鲁棒性仍然存在争议和未经证实，并且显然不容易使用常规DW-MRI检测。我们开创了一种新型扩散成像方法，该方法可以选择性地敏感到特定维度的神经结构，并且对神经细胞和水室的尺寸的变化应该更加敏感。因此，我们建议探索其用作检测和绘制大脑活动的方法。 基于脉冲梯度自旋回波（PGSE）方法的常规DW-MRI方法反映了多种结构特征的综合作用，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。我们已经开发了一种替代技术，即振荡梯度自旋回波（OGSE），该技术能够检测到在较小的空间尺度上扩散的限制，这导致对细胞尺寸变化的影响的高灵敏度。在这里，我们建议确定OGSE成像是否可以可靠地检测到神经活动引起的立即扩散变化。我们将应用优化的OGSE，常规BOLD和PGSE方法，以在给药前后的药理学剂（PCP）之前和之后对大鼠大脑进行图像，该药理剂（PCP）已知会引起可靠的稳健性，并在/或不使用预先治疗的药物中慢慢改变了脑激活的变化，以阻止效果（BINA）。这些缓慢变化的激活将允许衍生组织内微观结构变化的定量估计值。我们还将在与事件相关的设计，正常呼吸或在呼吸中呼吸时，在较高的前线刺激期间，以高时间分辨率记录大胆，OGSE和PGSE图像。通过比较这些各种图像系列的时间疗程，我们将能够验证与激活相关的扩散变化是否可以检测到比血管变化快的速度，以及高频的OGSE数据是否揭示了组织微观结构（神经元肿胀）的变化（神经元肿胀），并且偶然更快，并且比其他方法比其他方法更接近了。这些研究的潜在结果将是一种用高时空和空间分辨率绘制神经激活的方法，该方法可用于大脑功能组织的多样化人类和动物研究。