Optimal scan time of oxygen-15-labeled gas inhalation autoradiographic method for measurement of cerebral oxygen extraction fraction and cerebral oxygen metabolic rate
Optimal scan time of oxygen-15-labeled gas inhalation autoradiographic method for measurement of cerebral oxygen extraction fraction and cerebral oxygen metabolic rate
复制标题
氧15标记气体吸入放射自显影法测量脑氧提取分数和脑氧代谢率的最佳扫描时间
作者：
M. Shidahara;H. Watabe;Kyeong;N. Kudomi;Hiroshi Ito;H. Iida
目的使用放射自显影（ARG）方法，通过C15O、H215O、15O2示踪剂和正电子发射断层扫描（PET），可以估计局部脑血流量（CBF）、脑血容量、氧提取分数（OEF）和脑氧代谢率（CMRO2）。我们在本研究中的目标是优化 15O2 气体研究的扫描时间，以准确估计 OEF 和 CMRO2。方法我们通过使用计算机模拟改变扫描时间和估计 OEF 和 CMRO2 中组织异质性引起的误差来评估 OEF 中的统计噪声。通过重复组织时间活动曲线与噪声的信噪比 (S/N) 来研究统计噪声的特征，这些曲线是使用测量的平均动脉输入函数生成的，并假设 CBF = 20、50 和 80（ml/100 g/分钟）。还通过根据灰质和白质混合物不同比例的混合物的组织时间活动曲线估计的 OEF 和 CMRO2 来研究由组织异质性引起的误差。在模拟中，假设三个条件：（i）灰质和白质中的CBF（CBFg和CBFw）为80和20，灰质和白质中的OEF（Eg和Ew）为0.4和0.3，（ii）与条件（i）和（iii）相比，CBFg和CBFw下降了50％，Eg和Ew增加了50％。与条件(i)相比，CBFg和CBFw下降了80%，Eg和Ew增加了50%。结果扫描时间越长，从三个CBF值（20、50和80）估计的OEF值的信噪比越好。由于组织异质性，三种情况下的 OEF 估计误差随着扫描时间的延长而减少。同时对于CMRO2，扫描时间为3分钟是理想的。结论考虑到保持信噪比以及准确定量OEF和CMRO2，用ARG方法进行15O2吸入研究的最佳扫描时间为3分钟。
ObjectiveRegional cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2) can be estimated from C15O, H215O, and 15O2 tracers and positron emission tomography (PET) using an autoradiographic (ARG) method. Our objective in this study was to optimize the scan time for 15O2 gas study for accurate estimation of OEF and CMRO2.MethodsWe evaluated statistical noise in OEF by varying the scan time and error caused by the tissue heterogeneity in estimated OEF and CMRO2 using computer simulations. The characteristics of statistical noise were investigated by signal-to-noise (S/N) ratio from repeated tissue time activity curves with noise, which were generated using measured averaged arterial input function and assuming CBF = 20, 50, and 80 (ml/100 g per minute). Error caused by tissue heterogeneity was also investigated by estimated OEF and CMRO2 from tissue time activity curve with mixture of gray and white matter varying fraction of mixture. In the simulations, three conditions were assumed (i) CBF in gray and white matter (CBFg and CBFw) was 80 and 20, OEF in gray and white matter (Eg and Ew) was 0.4 and 0.3, (ii) CBFg and CBFw decreased by 50%, and Eg and Ew increased by 50% when compared with conditions (i) and (iii). CBFg and CBFw decreased by 80%, and Eg and Ew increased by 50% when compared with condition (i).ResultsThe longer scan time produced the better S/N ratio of estimated OEF value from three CBF values (20, 50, and 80). Errors of estimated OEF for three conditions owing to tissue heterogeneity decreased, as scan time took longer. Meanwhile in the case of CMRO2, 3 min of scan time was desirable.ConclusionsThe optimal scan time of 15O2 inhalation study with the ARG method was concluded to be 3 min from taking into account for maintaining the S/N ratio and the quantification of accurate OEF and CMRO2.
DOI：
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发表时间：
2006
期刊：
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影响因子：
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作者：
M. Mintun;M. Raichle;W. Martin
通讯作者：
M. Mintun;M. Raichle;W. Martin