Sources of systematic bias in hypercapnia-calibrated functional MRI estimation of oxygen metabolism
Sources of systematic bias in hypercapnia-calibrated functional MRI estimation of oxygen metabolism
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DOI：
10.1016/j.neuroimage.2006.08.033
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发表时间：
2007-01-01
期刊：
影响因子：
5.7
通讯作者：
Jezzard, Peter
中科院分区：
文献类型：
--
作者：
Chiarelli, Peter A.;Bulte, Daniel P.;Jezzard, Peter
神经激活过程中大脑氧化代谢率（CMPO2）的变化可以通过血氧水平依赖性（BOLD）功能磁共振成像（fMRI）和动脉自旋标记（ASL）fMRI测量来估计。所建立的方法依赖于同代谢血流量增加的时期（通常由 CO2 呼吸引起）来校准静息状态 CMRO2 下的 BOLD-CBF 关系。在这里，我们讨论 CMRO2 -CBF 数据中的系统偏差，该数据可以根据从 CO2 呼吸时期导出的校准常数 (M) 的值而引入。我们证明，当导出的校准值具有相对适中的幅度（1.5 T 时 M 在 10-15 范围内或大于 10-15）时，神经激活任务期间获取的 BOLD-CBF 数据的保真度对 CMRO2-CBF 耦合的紧密度以及耦合斜率影响很小。通过将 BOLD-CBF 空间中的网格标准重新表述为 CMRO2 -CBF 平面，我们演示了发生的非线性变换以及由此产生的系统偏差的来源。我们发现神经血管耦合研究的结果在很大程度上可以纯粹根据所使用的校准常数 M 的值来预测。我们的结果表明，M 的准确确定比之前想象的更重要，并表明在考虑特定大脑区域的 CMRO2-CBF 行为时，必须始终提供 BOLD-CBF 数据。 (c) 2006 Elsevier Inc. 保留所有权利。
The change in cerebral rate of oxidative metabolism (CMPO2) during neural activation may be estimated from blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) and arterial spin-labeling (ASL) fMRI measurements. The established method relies on an epoch of iso-metabolic blood flow increase, typically induced by CO2 breathing, to calibrate the BOLD-CBF relationship at resting-state CMRO2. Here, we discuss the systematic bias in CMRO2 -CBF data that can be introduced depending on the value derived for the calibration constant (M) from the CO2 breathing epoch. We demonstrate that the fidelity of BOLD-CBF data acquired during the neural activation task have low impact on the tightness of CMRO2-CBF coupling, as well as the coupling slope, when the derived calibration value is of a relatively moderate amplitude (M in the range of, or greater than, 10-15 at 1.5 T). Via the standard reformulation of a grid in BOLD-CBF space into the CMRO2 -CBF plane, we demonstrate the non-linear transformation that takes place and the sources of systematic bias that result. We find that the outcome of a neurovascular coupling study may be predicted to a large extent purely from the value of the calibration constant, M, that is used. Our results suggest that the accurate determination of M is of greater importance than thought previously and indicate that BOLD-CBF data must always be supplied when considering CMRO2-CBF behavior in a particular brain region. (c) 2006 Elsevier Inc. All rights reserved.