Jezzard P, Heineman F, Taylor J, DesPres D, Wen H, Balaban R S, Turner R
Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
NMR Biomed. 1994 Mar;7(1-2):35-44. doi: 10.1002/nbm.1940070107.
A gradient-echo echo planar imaging (EPI) sequence has been used to generate images of cat brain during respiratory challenges. Direct spectrophotometric measurements have been made simultaneously in order to correlate the changes in oxygen saturation as measured by spectrophotometry with the image intensity changes seen in the gradient-echo images. When blood volume remains approximately constant, as derived from the spectrophotometry data, good correlation is seen between calculated plots made of changes in the transverse relaxation rate, delta R2*, and the oxygen saturation as measured by spectrophotometry for much of the time course of the respiratory challenges of anoxia, apnea and hypercapnia. In some cases, the correlation is poorer during the recovery periods of the apnea and anoxia challenges. Those lower correlations can often be accounted for by changes in blood volume, which also affects the NMR relaxation rate. These results contribute to the understanding of the image intensity changes seen during functional brain imaging studies in humans.
梯度回波平面回波成像（EPI）序列已被用于在呼吸挑战期间生成猫脑图像。同时进行了直接分光光度测量，以便将分光光度法测量的氧饱和度变化与梯度回波图像中看到的图像强度变化相关联。当根据分光光度法数据得出血容量大致保持恒定时，在缺氧、呼吸暂停和高碳酸血症呼吸挑战的大部分时间过程中，由横向弛豫率变化（δR2*）计算得出的曲线与分光光度法测量的氧饱和度之间存在良好的相关性。在某些情况下，呼吸暂停和缺氧挑战恢复期的相关性较差。这些较低的相关性通常可以由血容量的变化来解释，血容量变化也会影响核磁共振弛豫率。这些结果有助于理解人类功能性脑成像研究中看到的图像强度变化。
