NMR STUDY OF BRAIN FUNCTION AND METABOLISM IN ANESTHESIA

全身麻醉药改变了许多对神经细胞重要的过程 功能。麻醉引起的脑事件改变的知识 将有助于理解麻醉剂的潜在机制 行动。麻醉对脑血流动力学及脑组织的影响 新陈代谢将通过磁共振成像和光谱学进行无创性评估。 提出了一个全面的多核磁共振项目，以 研究五种氟化全麻药氟烷的影响， 异氟醚、地氟烷和七氟醚--兔脑活体实验。 来自麻醉剂分子的19F核磁共振信号将被用来检测 他们的存在并评估他们在大脑中所处的环境。 将用ISIS研究麻醉剂在脑组织中的分布- 局部化二维化学位移成像。摄取动力学将是 在大脑中扎根。定义结合的分子环境 位点(S)T2-脑内麻醉剂分子的松弛时间将为 量过了。 全身麻醉引起的血流动力学变化将通过 1HBOLD(血氧水平依赖)对比成像。分析 3D图像块的时间序列将由探索性的 精确功能活动图的无监督方法。3D磁共振血管成像 将被记录下来，以消除大静脉的影响。 麻醉期间脑能量代谢的区域性变化 将由ISIS本地化的31P 2D化学位移进行检测和监控 保留化学位移信息的成像。谷氨酸的变化， 将绘制谷氨酰胺、γ-氨基丁酸和乳酸水平图 使用水抑制的ISIS-2D CSI自旋回波1H谱。 来自分布图、功能图和代谢图的数据将相互关联 每一幅都有高分辨率的1H解剖图像 这项研究。所研究过程的真实基线值为 通过对清醒的兔脑进行测量而建立的。初步结果 从19F，31P和1H的4.7T磁共振实验证明 建议项目的可行性。

General anesthetics modify many processes important to nerve cell function. Knowledge of anesthesia-induced alterations in brain events will help in the understanding of the mechanism underlying anesthetic action. Effects of anesthesia on cerebral hemodynamics and cerebral metabolism will be assessed noninvasively by MR imaging and spectroscopy. A comprehensive multinuclear magnetic resonance project is proposed to study the influence of five fluorinated general anesthetics - halothane, isoflurane, desflurane and sevoflurane - on rabbit brain in vivo. The 19F NMR signals from the anesthetic molecules will be used to detect their presence and assess the environments they occupy in brain. Distribution of anesthetic within brain tissue will be studied with ISIS- localized two-dimensional Chemical Shift Imaging. Uptake kinetics will be established in brain. To define the molecular environment of the binding site(s) T2-relaxation times of anesthetic molecules in brain will be measured. Hemodynamic changes induced by general anesthesia will be visualized using 1H BOLD (Blood Oxygenation Level Dependent) contrast imaging. Analysis of the time sequence of 3D image blocks will be performed by an exploratory unsupervised method to exact functional activity maps. 3D MR angiograms will be recorded to eliminate effects from large veins. Regional changes in cerebral energy metabolism occurring during anesthesia will be detected and monitored by ISIS-localized 31P 2D-Chemical Shift Imaging which retains chemical shift information. Changes in glutamate, glutamine, gamma-aminobutyric acid and lactic acid levels will be mapped using water-suppressed, ISIS-2D CSI spin-echo 1H spectroscopy. Data from distribution, functional, and metabolic maps will be correlated with each and with high resolution 1H anatomical images obtained during the study. True baseline values for the processes studied will be established with measurements on awake rabbit brain. Preliminary results from 19F, 31P and 1H MR experiments at 4.7T are presented to demonstrate the feasibility of the proposed project.