PET measurements of CBF, OEF, and CMRO2 without arterial sampling in hyperacute ischemic stroke:: Method and error analysis
PET measurements of CBF, OEF, and CMRO2 without arterial sampling in hyperacute ischemic stroke:: Method and error analysis
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DOI：
10.1007/bf02985612
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发表时间：
2004-02-01
影响因子：
2.6
通讯作者：
Hatazawa, J
中科院分区：
文献类型：
--
作者：
Ibaraki, M;Shimosegawa, E;Hatazawa, J
提出了一种利用正电子发射断层扫描（PET）无需动脉取样即可相对测量超急性缺血性脑卒中患者脑血流量（CBF）、氧提取分数（OEF）和氧代谢率（CMRO2）的方法。方法：该方法需要两次PET扫描，一次注射(H2O)-O-15，一次吸入O-15(2)，并通过查表法计算相对于参考脑区的区域CBF、CMRO2和OEF。在本研究中，我们计算了“相对查找表”，将相对 CBF 与相对 (H2O)-O-15 计数、相对 CMRO2 与相对 O-15(2) 计数以及相对 OEF 与相对 O-15(2)/(H2O)-O-15 计数相关。查找表计算中应用了两个假设：1) 在参考区域，CBF 和 OEF 分别假设为 50.0 ml/min/100 ml 和 0.40，2) 假设整个大脑的脑血量 (CBV) 恒定为 4.0 ml/100 ml。进行了模拟研究，以估计从假设得出的本方法的误差。结果：对于相对 CBF 测量，参考 CBF 的 20% 变化会给测量的相对 CBF 带来约 +/-10% 的最大误差。当相对CBF和OEF降低时，CBV的变化导致测量的OEF和CMRO2误差较大。当相对 OEF 大于 1.0 时，由 CBV 50% 变化引起的测量相对 OEF 误差在 0.8 相对 CBF 时在 +/-8% 以内，在 0.4 相对 CBF 时在 +/-12% 以内。结论：CBV 效应导致缺血核心区域的 OEF 和 CMRO2 估计误差较大，相对 CBF 和/或 OEF 降低，但在相对 OEF 值大于 1.0 的“痛苦灌注”区域仅产生轻微误差。本方法使 PET 测量比传统方法更简单，并增加了对超急性中风患者发病后数小时脑循环和氧代谢的了解。
A method for relative measurement of cerebral blood flow (CBF), oxygen extraction fraction (OEF), and metabolic rate of oxygen (CMRO2) Using positron emission tomography (PET) without arterial sampling in patients with hyperacute ischemic stroke was presented. Methods: The method requires two PET scans, one for (H2O)-O-15 injection and one for O-15(2) inhalation, and calculates regional CBF, CMRO2, and OEF relative to those at the reference brain region by means of table-lookup method. In this study, we calculated "relative lookup-tables" which relate relative CBF to relative (H2O)-O-15 count, relative CMRO2 to relative O-15(2) count, and relative OEF to relative O-15(2)/(H2O)-O-15 count. Two assumptions were applied to the lookup-table calculation: 1) In the reference region, CBF and OEF were assumed to be 50.0 ml/min/100 ml and 0.40, respectively, 2) Cerebral blood volume (CBV) was assumed to be constant at 4.0 ml/100 ml over the whole brain. Simulation studies were done to estimate the error of the present method derived from the assumptions. Results: For relative CBF measurements, 20% variation in reference CBF gave about +/-10% error for measured relative CBF at maximum. Changes in CBV caused relatively large errors in measured OEF and CMRO2 when relative CBF and OEF decreased. Errors for measured relative OEF caused by 50% variation in CBV were within +/-8% at 0.8 of relative CBF and +/-12% at 0.4 of relative CBF when relative OEF was greater than 1.0. Conclusion: CBV effects caused larger errors in estimated OEF and CMRO2 in the region of the ischemic core with decreasing relative CBF and/or OEF but only slight errors in the region of "misery perfusion" with relative OEF values greater than 1.0. The present method makes PET measurements simpler than with the conventional method and increases understanding of the cerebral circulation and oxygen metabolism in patients with hyperacute stroke of several hours after onset.