Zhou Yongxia, Rodgers Zachary B, Kuo Anderson H
Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104.
Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104.
Magn Reson Imaging. 2015 Jun;33(5):566-76. doi: 10.1016/j.mri.2015.02.018. Epub 2015 Feb 20.
To compare cerebrovascular reactivity (CVR) quantified with pseudo-continuous arterial spin labeling (pCASL) and blood oxygen level dependent (BOLD) fMRI techniques.
Sixteen healthy volunteers (age: 37.8±14.3years; 6 women and 10 men; education attainment: 17±2.1years) were recruited and completed a 5% CO2 gas-mixture breathing paradigm at 3T field strength. ASL and BOLD images were acquired for CVR determination assuming that mild hypercapnia does not affect the cerebral metabolic rate of oxygen. Both CVR quantifications were derived as the ratio of the fractional cerebral blood flow (CBF) or BOLD signal change over the change in end-tidal CO2 pressure.
The absolute CBF, BOLD and CVR measures were consistent with literature values. CBF derived CVR was 5.11±0.87%/mmHg in gray matter (GM) and 4.64±0.37%/mmHg in parenchyma. BOLD CVR was 0.23±0.04%/mmHg and 0.22±0.04%/mmHg for GM and parenchyma respectively. The most significant correlations between BOLD and CBF-based CVRs were also in GM structures, with greater vascular response in occipital cortex than in frontal and parietal lobes (6.8%/mmHg versus 4.5%/mmHg, 50% greater). Parenchymal BOLD CVR correlated significantly with the fractional change in CBF in response to hypercapnia (r=0.61, P=0.01), suggesting the BOLD response to be significantly flow driven. GM CBF decreased with age in room air (-5.58mL/100g/min per decade for GM; r=-0.51, P=0.05), but there was no association of CBF with age during hypercapnia. A trend toward increased pCASL CVR with age was observed, scaling as 0.64%/mmHg per decade for GM.
Consistent with previously reported CVR values, our results suggest that BOLD and CBF CVR techniques are complementary to each other in evaluating neuronal and vascular underpinning of hemodynamic processes.
比较用伪连续动脉自旋标记（pCASL）和血氧水平依赖（BOLD）功能磁共振成像（fMRI）技术量化的脑血管反应性（CVR）。
招募了16名健康志愿者（年龄：37.8±14.3岁；6名女性和10名男性；受教育年限：17±2.1年），并在3T场强下完成了5%二氧化碳混合气体呼吸模式。假设轻度高碳酸血症不影响脑氧代谢率，采集了动脉自旋标记（ASL）和BOLD图像以测定CVR。两种CVR量化指标均通过脑血流量（CBF）分数或BOLD信号变化与呼气末二氧化碳分压变化的比值得出。
绝对CBF、BOLD和CVR测量值与文献值一致。基于CBF得出的CVR在灰质（GM）中为5.11±0.87%/mmHg（毫米汞柱），在脑实质中为4.64±0.37%/mmHg。GM和脑实质的BOLD CVR分别为0.23±0.（此处原文有误，应为0.23±0.04%/mmHg）04%/mmHg和0.22±0.04%/mmHg。基于BOLD和CBF的CVR之间最显著的相关性也存在于GM结构中，枕叶皮质比额叶和顶叶具有更大的血管反应（6.8%/mmHg对4.5%/mmHg，大50%）。脑实质BOLD CVR与高碳酸血症时CBF的分数变化显著相关（r = 0.61，P = 0.01），表明BOLD反应受血流显著驱动。在室内空气中，GM CBF随年龄下降（GM每十年下降-5.58mL/100g/min；r = -0.51，P = 0.05），但在高碳酸血症期间CBF与年龄无关联。观察到pCASL CVR有随年龄增加的趋势，GM每十年增加0.64%/mmHg。
与先前报道的CVR值一致，我们的结果表明BOLD和CBF CVR技术在评估血流动力学过程的神经元和血管基础方面相互补充。
