Development of a Tissue-Specific fMRI Technique

描述（由申请人提供）：大多数当前的功能性磁共振成像（fMRI）技术测量由血氧水平依赖性（BOLD）对比度引起的水T2* 或T2的变化，其基于对神经元活动的血液动力学反应。然而，神经元活动和血液动力学之间的耦合很复杂，基于血液动力学的fMRI的空间和时间分辨率本质上受到血管系统特性的限制。为了提高空间特异性并获得更快的时间响应，成像信号应该直接源自组织（即，神经细胞），而不是血管。本研究将发展一种新的基于组织T1 rho的功能磁共振成像技术，并对其时空特性进行研究。T1 rho是在施加自旋锁定脉冲期间旋转坐标系中的自旋-晶格弛豫时间，并且已经发现对细胞内pH水平以及大分子组成和密度敏感。这种组织T1 rho fMRI对比度可能是由激活过程中神经元细胞的酸化引起的，并且预计会更快，空间起源比基于血液动力学的fMRI更特异于神经活动的位点。因此，组织T1 rho功能磁共振成像对比可以大大提高基础和临床神经科学研究中的非侵入性功能脑映射的准确性。公共卫生相关性：这项研究旨在开发一种新的非侵入性脑成像技术，可以比传统技术更快，更准确。

DESCRIPTION (provided by applicant): Most current functional magnetic resonance imaging (fMRI) techniques measure the change in water T2* or T2 caused by blood oxygenation-level dependent (BOLD) contrast, which are based on the hemodynamic responses to neuronal activity. However, the coupling between neuronal activity and hemodynamics is complex, and the spatial and temporal resolutions of hemodynamic-based fMRI are intrinsically limited by properties of the vasculature. In order to improve the spatial specificity and to obtain a faster temporal response, the imaging signal should directly originate from tissue (i.e., neuronal cells), rather than from blood vessels. In this project, a novel fMRI technique based on tissue T1rho will be developed, and its spatial and temporal characteristics will be examined. T1rho is the spin-lattice relaxation time in the rotating frame during an applied spin-locking pulse, and has been found to be sensitive to intracellular pH level as well as macromolecular composition and density. This tissue T1rho fMRI contrast is presumably induced by an acidification of neuronal cells during activation, and is expected to be faster, with spatial origins more specific to sites of neural activity than hemodynamic-based fMRI. Thus, tissue T1rho fMRI contrast may greatly improve the accuracy of noninvasive functional brain mapping in basic and clinical neuroscience research. PUBLIC HEALTH RELEVANCE: This investigation aims to develop a novel non-invasive brain imaging technique that can be faster and more accurate than conventional techniques.