Noninvasive optical evaluation of spontaneous low frequency oscillations in cerebral hemodynamics
Noninvasive optical evaluation of spontaneous low frequency oscillations in cerebral hemodynamics
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DOI：
10.1016/j.neuroimage.2012.05.069
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发表时间：
2012-09-01
期刊：
影响因子：
5.7
通讯作者：
Yu, Guoqiang
中科院分区：
文献类型：
--
作者：
Cheng, Ran;Shang, Yu;Yu, Guoqiang
平均动脉压（MAP）和脑血流速度（CBFV）在0.1Hz附近出现自发性低频振荡（LFO）。以往的研究表明，可以通过定量MAP和CBFV的LFO之间的相移来评估主要动脉中的脑自动调节。然而，许多脑疾病与脑中的异常微血管和组织功能障碍有关，并且这些异常的定量需要直接测量脑组织血流动力学。这项初步研究使用了一种新型的混合近红外漫射光学仪器来无创地同时检测脑血流（CBF）和脑氧合的LFO（即，氧合/脱氧/总血红蛋白浓度：[HbO（2）]/[Hb]/THC）。应用混合式脑血流仪和手指体积描记器，同时测定了15名健康受试者在安静、70 °头高位倾斜（HUT）和0.1Hz强制呼吸时的CBF、[HbO（2）]、[Hb]、THC和MAP的动态变化。使用功率谱分析从测量变量中提取LFO，并从相应的传递函数计算MAP和每个测量的血流动力学变量之间的LFO的相移和相干性。相干性水平（> 0.4）用于判断LFO测量的成功。我们发现CBF、[HbO（2）]和THC是检测LFO的可靠血流动力学参数，HUT是量化血流动力学LFO相移的最稳健和稳定的方案。与其他相关研究相比，我们的研究在检测脑LFO方面取得了相似的成功率。CBF中LFO的相移也接近于其他组报告的CBFV中的相移，尽管在强制呼吸期间脑氧合测量的结果在研究中有所不同。未来的研究将探讨脑损伤患者的脑LFO，并通过定量LFO相移来评估其脑自动调节能力和神经认知功能。(c)2012 Elsevier Inc. All rights reserved.
Spontaneous low frequency oscillations (LFOs) around 0.1 Hz have been observed in mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV). Previous studies have shown that cerebral autoregulation in major arteries can be assessed by quantification of the phase shift between LFOs of MAP and CBFV. However, many cerebral diseases are associated with abnormal microvasculature and tissue dysfunction in brain, and quantification of these abnormalities requires direct measurement of cerebral tissue hemodynamics. This pilot study used a novel hybrid near-infrared diffuse optical instrument to noninvasively and simultaneously detect LFOs of cerebral blood flow (CBF) and cerebral oxygenation (i.e., oxygenated/deoxygenated/total hemoglobin concentration: [HbO(2)]/[Hb]/THC) in human prefrontal cortex. Using the hybrid instrument and a finger plethysmograph, the dynamic changes of CBF, [HbO(2)], [Hb], THC and MAP were concurrently measured in 15 healthy subjects at rest, during 70 degrees head-up-tilting (HUT) and during enforced breathing at 0.1 Hz. The LFOs were extracted from the measured variables using power spectral analysis, and the phase shifts and coherences of LFOs between MAP and each of the measured hemodynamic variables were calculated from the corresponding transfer functions. Levels of coherence (> 0.4) were used to judge the success of LFO measurements. We found that CBF, [HbO(2)] and THC were reliable hemodynamic parameters in detecting LFOs and HUT was the most robust and stable protocol for quantifying phase shifts of hemodynamic LFOs. Comparing with other relevant studies, similar success rates for detecting cerebral LFOs have been achieved in our study. The phase shifts of LFOs in CBF were also close to those in CBFV reported by other groups, although the results in cerebral oxygenation measurements during enforced breathing varied across studies. Future study will investigate cerebral LFOs in patients with cerebral impairment and evaluate their cerebral autoregulation capabilities and neurocognitive functions via the quantification of LFO phase shifts. (c) 2012 Elsevier Inc. All rights reserved.