TRACER-KINETIC MODELS FOR MEASURING CEREBRAL BLOOD-FLOW USING EXTERNALLY DETECTED RADIOTRACERS
TRACER-KINETIC MODELS FOR MEASURING CEREBRAL BLOOD-FLOW USING EXTERNALLY DETECTED RADIOTRACERS
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DOI：
10.1038/jcbfm.1987.88
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发表时间：
1987-08-01
影响因子：
6.3
通讯作者：
RAICHLE, ME
中科院分区：
文献类型：
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作者：
LARSON, KB;MARKHAM, J;RAICHLE, ME
目前正电子发射断层扫描（PET）采用的所有示踪剂动力学模型都是基于房室假设。当我们实施凯蒂组织放射自显影技术来测量CBF时，我们第一次表明隔室模型在某些情况下与PET一起使用时可能会受到严重限制，并观察到产生的CBF估计值，而不是保持不变（在可预测的统计不确定性内），当T > 1分钟时，随着扫描持续时间T的增加而下降。在排除其他解释后，我们的结论是，一室模型不具有足够的现实性，以充分描述标记水在脑中的运动。这篇文章叙述了我们寻找更现实的替代模型。我们给出了我们的推导和结果的残留检测脉冲响应的单位毛细血管组织系统，我们的两个候选分布参数模型。在从最简单的开始的一系列试验中，我们根据适当的残留检测实验的数据测试了四个逐渐详细的候选模型。在这些研究中，我们产生了高时间分辨率的计数率数据，反映了恒河猴大脑中放射性标记水的吸收和洗脱的历史。我们描述了我们的数据处理产生模型独立的经验值的CBF和其他参数。通过将这些代入我们的试验模型函数，我们能够将模型预测与实验动态计数率历史进行直接比较，证实我们对一室模型的保留是有根据的，并迫使我们拒绝其他两个。我们的结论是，一个双屏障分布参数模型有可能作为一个替代的凯蒂模型在PET测量患者的CBF，特别是当扫描持续时间为T > 1分钟是理想的。
All tracer-kinetic models currently employed with positron-emission tomography (PET) are based on compartmental assumptions. Our first indication that a compartmental model might suffer from severe limitations in certain circumstances when used with PET occurred when we implemented the Kety tissue-autoradiography technique for measuring CBF and observed that the resulting CBF estimates, rather than remaining constant (to within predictable statistical uncertainty) as expected, fell with increasing scan duration T when T > 1 min. After ruling out other explanations, we concluded that a one-compartment model does not possess sufficient realism for adequately describing the movement of labeled water in brain. This article recounts our search for more realistic substitute models. We give our derivations and results for the residue-detection impulse responses for unit capillary-tissue systems of our two candidate distributed-parameter models. In a sequence of trials beginning with the simplest, we tested four progressively more detailed candidate models against data from appropriate residue-detection experiments. In these, we generated high-temporal-resolution counting-rate data reflecting the history of radiolabeled-water uptake and washout in the brains of rhesus monkeys. We describe our treatment of the data to yield model-independent empirical values of CBF and of other parameters. By substituting these into our trial-model functions, we were able to make direct comparisons of the model predictions with the experimental dynamic counting-rate histories, confirming that our reservations concerning the one-compartment model were well founded and obliging us to reject two others. We conclude that a two-barrier distributed-parameter model has the potential of serving as a substitute for the Kety model in PET measurements of CBF in patients, especially when scan durations for T > 1 min are desired.