Huang S C, Feng D G, Phelps M E
J Cereb Blood Flow Metab. 1986 Feb;6(1):105-19. doi: 10.1038/jcbfm.1986.13.
The use of oxygen-15 and dynamic positron emission tomography (PET) for the measurement of CMRO was investigated in terms of the achievable accuracy of CMRO and its sensitivity to model configuration assumed in the estimation. Three models of different descriptions for the vascular radioactivity in tissue were examined by computer simulation. By simulating the tracer kinetics with one model and curve fitting them with another, it was found that the CMRO measurement was very sensitive to the model configuration used and it needed kinetic data of low noise level to determine the correct model to use. The approach of sensitivity functions and covariance matrices was used to examine the estimation reliability and error propagation of the model parameters. It was found that for all three model configurations examined the reliability of the CMRO estimate was dependent on the blood flow and oxygen extraction fraction in tissue (approximately 2% in tissues of high blood flow and normal extraction and 10% in tissues of low blood flow and low extraction fraction, in a study of 1 X 10(6) counts/brain slice in 3 min). The estimation reliability is drastically decreased if the total data collection time is reduced to 1 min but is not critically sensitive to the scan sampling interval used. Estimating blood flow or vascular volume simultaneously with CMRO will reduce the reliability of the CMRO estimate by approximately 50%. Propagation of parameter error from blood flow or vascular volume to CMRO is dependent on the model configuration as well as the scanning schedule and estimation procedure used. Results from the study provide useful information for improving the study procedure of CMRO measurements. The present study also illustrates a general representation of PET measurements and an approach that can be applied to other tracer techniques in PET for selecting appropriate model configurations and for designing proper experimental procedures.
研究了使用氧 - 15和动态正电子发射断层扫描（PET）测量脑代谢率（CMRO）的情况，涉及CMRO可达到的准确度及其对估计中假设的模型配置的敏感性。通过计算机模拟研究了三种对组织中血管放射性不同描述的模型。通过用一种模型模拟示踪剂动力学并用另一种模型进行曲线拟合，发现CMRO测量对所使用的模型配置非常敏感，并且需要低噪声水平的动力学数据来确定要使用的正确模型。使用灵敏度函数和协方差矩阵的方法来检查模型参数的估计可靠性和误差传播。发现在所有三种研究的模型配置中，CMRO估计的可靠性取决于组织中的血流量和氧摄取分数（在一项研究中，每3分钟每脑切片1×10⁶计数，高血流量和正常摄取的组织中约为2％，低血流量和低摄取分数的组织中约为10％）。如果总数据采集时间减少到1分钟，估计可靠性会急剧下降，但对所使用的扫描采样间隔不是非常敏感。同时估计血流量或血管容积与CMRO会使CMRO估计的可靠性降低约50％。参数误差从血流量或血管容积传播到CMRO取决于模型配置以及所使用的扫描时间表和估计程序。该研究结果为改进CMRO测量的研究程序提供了有用信息。本研究还说明了PET测量的一般表示方法以及一种可应用于PET中其他示踪技术的方法，用于选择合适的模型配置和设计适当的实验程序。
