Assessing the repeatability of absolute CMRO(2), OEF and haemodynamic measurements from calibrated fMRI.
Assessing the repeatability of absolute CMRO(2), OEF and haemodynamic measurements from calibrated fMRI.
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评估来自校准fMRI的绝对CMRO（2），OEF和血液动力学测量的可重复性。
DOI：
10.1016/j.neuroimage.2018.02.020
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发表时间：
2018-06
期刊：
影响因子：
5.7
通讯作者：
Wise RG
中科院分区：
文献类型：
--
作者：
Merola A;Germuska MA;Murphy K;Wise RG
由于大脑中的能量代谢主要是氧化性的，因此测量脑氧消耗代谢率（cro2）是量化大脑活动和组织活力的理想生物标志物。目前，基于氧同位素的PET技术是获得全脑cmor2图谱的金标准。作为替代方案的MRI技术包括双校准功能磁共振成像（dcFMRI）方法，该方法利用在高碳酸血症-高氧实验中同时测量BOLD和ASL信号来调节脑血流量和氧合。在这项研究中，我们量化了我们实验室开发的dcFMRI方法的可重复性，评估了其局限性，并告知其在旨在表征人类脑组织随时间代谢状态的研究中的应用。我们的分析重点是基于解析描述获得的双回波GRE信号的正演模型估计氧提取分数（OEF），脑血流量（CBF）， CBF相关脑血管反应性（CVR）和CMRO2。从两个不同的数据集中，以大块灰质和体素分辨率计算会话内和会话之间的可重复性指数，并最终与先前MRI和PET测量获得的类似指数进行比较。内,between-session intra-subject值变异系数(CVintra)计算从散装灰质估计6.7 ± 6.6%(平均 ± std)和10.5 ±OEF 9.7%,6.9 ± 6%和5.5±4.7% CBF, 12 ± 9.7%和12.3± CMRO2为10%。变异系数（CV）和类内相关系数（ICC）图显示了重复性指标的空间分布，提示了方法的可行性限制。综上所述，考虑到与其他MRI方法相比具有更高的空间灵敏度，结果显示估计的生理参数与文献报道总体上一致，并且具有令人满意的可重复性，其性能取决于所分析的具体参数，所考虑的空间分辨率和研究设计。两个数据集（N1 = 10和N2 = 16）从双校准fMRI实验呼吸任务考虑。给出了用最近提出的估计方法计算的OEF、CBF、CVR和cmor2的图。在会话内和会话之间的设计中，报告了全局和体素可重复性的估计指数。结果表明，与以前的研究相比，该方法在重复性和空间分辨率之间取得了良好的平衡。
As energy metabolism in the brain is largely oxidative, the measurement of cerebral metabolic rate of oxygen consumption (CMRO2) is a desirable biomarker for quantifying brain activity and tissue viability. Currently, PET techniques based on oxygen isotopes are the gold standard for obtaining whole brain CMRO2 maps. Among MRI techniques that have been developed as an alternative are dual calibrated fMRI (dcFMRI) methods, which exploit simultaneous measurements of BOLD and ASL signals during a hypercapnic-hyperoxic experiment to modulate brain blood flow and oxygenation. In this study we quantified the repeatability of a dcFMRI approach developed in our lab, evaluating its limits and informing its application in studies aimed at characterising the metabolic state of human brain tissue over time. Our analysis focussed on the estimates of oxygen extraction fraction (OEF), cerebral blood flow (CBF), CBF-related cerebrovascular reactivity (CVR) and CMRO2 based on a forward model that describes analytically the acquired dual echo GRE signal. Indices of within- and between-session repeatability are calculated from two different datasets both at a bulk grey matter and at a voxel-wise resolution and finally compared with similar indices obtained from previous MRI and PET measurements. Within- and between-session values of intra-subject coefficient of variation (CVintra) calculated from bulk grey matter estimates 6.7 ± 6.6% (mean ± std.) and 10.5 ± 9.7% for OEF, 6.9 ± 6% and 5.5 ± 4.7% for CBF, 12 ± 9.7% and 12.3 ± 10% for CMRO2. Coefficient of variation (CV) and intraclass correlation coefficient (ICC) maps showed the spatial distribution of the repeatability metrics, informing on the feasibility limits of the method. In conclusion, results show an overall consistency of the estimated physiological parameters with literature reports and a satisfactory level of repeatability considering the higher spatial sensitivity compared to other MRI methods, with varied performance depending on the specific parameter under analysis, on the spatial resolution considered and on the study design. Two datasets (N1 = 10 and N2 = 16) from dual calibrated fMRI experiments with respiratory tasks are considered. Maps of OEF, CBF, CVR and CMRO2 calculated with a recently proposed estimation approach are shown. Estimated indices of global and voxel-wise repeatability are reported for within- and between- session designs. Results show a good trade-off between repeatability and spatial resolution when compared to previous studies.
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影响因子：
5.7
作者：
Jenkinson, M;Bannister, P;Smith, S
通讯作者：
Smith, S
影响因子：
2.5
作者：
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Uludag, Kamil
DOI：
10.1073/pnas.0909711107
发表时间：
2010-05-04
影响因子：
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作者：
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作者：
Gauthier, Claudine J.;Hoge, Richard D.
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影响因子：
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作者：
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