Reduced transit-time sensitivity in noninvasive magnetic resonance imaging of human cerebral blood flow
Reduced transit-time sensitivity in noninvasive magnetic resonance imaging of human cerebral blood flow
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DOI：
10.1097/00004647-199611000-00019
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发表时间：
1996-11-01
影响因子：
6.3
通讯作者：
Detre, JA
中科院分区：
文献类型：
--
作者：
Alsop, DC;Detre, JA
在此，我们提出了一个理论框架和实验方法，以更准确地解释使用内源磁共振成像（MRI）对比度的定量人体灌注成像中的传输效应。论证了连续和脉冲反转自旋标记实验的理论渡越时间灵敏度。我们建议在连续标记后引入延迟，并从理论上证明延迟的引入会显着降低灌注成像的传输时间敏感性。还推导了磁化转移饱和对这种改进的连续标记实验的影响，并检查了灌注信号完全驻留在组织内而不是动脉微脉管系统内的假设。我们提出的结果证明了在回波平面扫描仪上进行延迟连续标记实验的实施，用于测量正常志愿者的脑血流（CBF）。通过改变延迟，我们估计动脉系统中的传输时间，这是评估我们的量化准确性所必需的值。讨论了从标记平面到动脉微脉管系统的传输时间和到组织本身的传输时间的不确定性对灌注定量准确性的影响，发现在灰质中很小，但在白质中仍然可能很重要。还提出了一种远距离测量T-1的新方法，该方法快速、对脑脊液污染不敏感，并且与磁化传递饱和度的应用兼容。这些方法结合起来生成静息和高碳CBF 的定量图。
Herein, we present a theoretical framework and experimental methods to more accurately account for transit effects in quantitative human perfusion imaging using endogenous magnetic resonance imaging (MRI) contrast. The theoretical transit time sensitivities of both continuous and pulsed inversion spin tagging experiments are demonstrated. We propose introducing a delay following continuous labeling, and demonstrate theoretically that introduction of a delay dramatically reduces the transit time sensitivity of perfusion imaging. The effects of magnetization transfer saturation on this modified continuous labeling experiment are also derived, and the assumption that the perfusion signal resides entirely within tissue rather than the arterial microvasculature is examined. We present results demonstrating the implementation of the continuous tagging experiment with delay on an echoplanar scanner for measuring cerebral blood now (CBF) in normal volunteers. By varying the delay, we estimate transit times in the arterial system, values that are necessary for assessing the accuracy of our quantification. The effect of uncertainties in the transit time from the tagging plane to the arterial microvasculature and the transit rime to the tissue itself on the accuracy of perfusion quantification is discussed and found to be small in gray matter but still potentially significant in white matter. A novel method far measuring T-1, which is fast, insensitive to contamination by cerebrospinal fluid, and compatible with the application of magnetization transfer saturation, is also presented. The methods are combined to produce quantitative maps of resting and hypercarbic CBF.