NMR STUDY OF BRAIN FUNCTION AND METABOLISM IN ANESTHESIA

全身麻醉药改变了神经细胞的许多重要过程 功能 麻醉诱导的脑事件改变的知识 将有助于了解麻醉剂的潜在机制 行动上 麻醉对脑血流动力学及脑血流动力学的影响 将通过MR成像和光谱学非侵入性地评估代谢。 提出了一个全面的多核磁共振项目， 研究五种氟代全身麻醉药氟烷， 异氟醚、地氟醚和七氟醚对兔脑的影响。 来自麻醉剂分子的19 F NMR信号将用于检测 它们的存在并评估它们在大脑中占据的环境。 将使用ISIS研究麻醉剂在脑组织内的分布- 局部二维化学位移成像 摄取动力学将是 在大脑中建立。 来定义结合的分子环境 大脑中麻醉剂分子的T2弛豫时间将 测定了 全身麻醉诱导的血流动力学变化将使用 1H BOLD（血氧水平依赖性）对比成像。 分析 3D图像块的时间序列将由探索性 无监督的方法来精确的功能活动图。 3D MR血管造影 将被记录以消除大静脉的影响。 麻醉期间脑能量代谢的局部变化 将通过ISIS定位的31 P二维化学位移检测和监测 保留化学位移信息的成像。 谷氨酸盐的变化， 谷氨酰胺、γ-氨基丁酸和乳酸水平将被绘制成地图， 使用水抑制的ISIS-2D CSI自旋回波1H光谱。 来自分布图、功能图和代谢图的数据将被关联 每一个和高分辨率1H解剖图像， 书房 研究过程的真实基线值为 通过对清醒的兔子大脑的测量来建立。 初步结果 19 F、31 P和1HNMR实验结果表明， 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.