A method for simultaneous measurements of cerebral blood flow and cerebral metabolic rate for oxygen by magnetic resonance imaging.

本研究建立了一种磁共振成像（MRI）同时测量脑血流量（CBF）和脑氧代谢率（CMRo_2）的方法<17>。使用快速自旋回波序列获得猫脑图像。在MRI扫描期间，同时进行水-17的静脉输注和一系列动脉血样的收集。根据~（17）水灌注引起的脑信号强度变化，计算脑内~（17）水浓度。动脉血中的水-17浓度通过<17>1H NMR光谱直接测量。在此基础上，利用放射自显影技术成功地测定了猫的脑血流量，并以~（17）O标记的氧气为示踪剂，用MRI同时测定了猫的脑血流量和CMRo_2<17>。使用快速自旋回波序列获得猫脑图像。在吸入氧-17气体期间，进行一系列MRI扫描和动脉血采样。根据吸入氧-17引起的脑信号强度的变化，计算脑的代谢水-17浓度。通过1H NMR光谱法直接测量动脉血中的代谢水-17浓度<17>。应用卷积积分和最小二乘法，由这些数据同时计算出CBF和CMRo_2。然而，所获得的值不足以作为合理值。为了解决这个问题，信号强度的变化，引起的氧-17气体吸入，应该更灵敏地检测到MRI。

A method for simultaneous measurements of cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRo_2) by magnetic resonance imaging (MRI) was developed.First, CBF was measured in cats by MRI,using ^<17>O-labeled water (water-17) as a tracer. Cat brain images were obtained using a fast spin-echo sequence. Intravenous infusion of water-17 and collection of a series of arterial blood samples were simultaneously performed during the MRI scan. From changes in brain signal intensity induced by water-17 infusion, water-17 concentration of brain were calculared. Water-17 concentration in arterial blood was measured directly by ^<17>O NMR spectroscopy. From these data, CBF was successfully determined using an in vivo autoradiographic strategy.Next, CBF and CMRo_2 were measured simultaneously in cats by MRI,using ^<17>O-labeled oxygen gas (oxygen-17 gas) as a tracer. Cat brain images were obtained using a fast spin-echo sequence. During inhalation of oxygen-17 gas, a series of MRI scans and arterial blood samplings were performed. From changes in brain signal intensity induced by oxygen-17 inhalation, metabolic water-17 concentration of brain were calculated. Metabolic water-17 concentration in arterial blood was measured directly by ^<17>O NMR spectroscopy. Applying convolution integral and least square method, CBF and CMRo_2 were simultaneously calculated from these data. However, the obtained values were not sufficient as reasonable values. To resolve this problem, changes in signal intensity, induced by oxygen-17 gas inhalation, should be detected much more sensitively by MRI.