Perturbation of the BOLD response by a contrast agent and interpretation through a modified balloon model
Perturbation of the BOLD response by a contrast agent and interpretation through a modified balloon model
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DOI：
10.1016/j.neuroimage.2009.06.038
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发表时间：
2009-10-15
期刊：
影响因子：
5.7
通讯作者：
Gowland, P. A.
中科院分区：
文献类型：
--
作者：
Blockley, N. P.;Francis, S. T.;Gowland, P. A.
本研究使用顺磁性造影剂的输注来干扰血管内血液敏感性，并研究其对BOLD血流动力学反应的影响。一个三房室BOLD信号模型结合改进的气球模型被开发来解释MR信号。该模型纳入了动脉血容量，以模拟造影剂引起的信号变化。将BOLD信号模型拟合到实验数据以检验动脉血容量在激活期间改变的假设。据发现，允许动脉血容量的变化，而不是假设这种变化是可以忽略不计的文献中经常假设，提供了一个更好的拟合实验数据，特别是在BOLD过冲。无论是否允许动脉血容量改变，通过假设该特征是由于延迟的静脉顺应性，刺激后下冲拟合良好。然而，刺激后血容量的最终升高以极长的时间常数衰减，在4.8s刺激后需要超过55s才能恢复到基线。这里测量的刺激后信号变化可以替代地通过代谢中的刺激后升高来描述。需要一种替代氧提取模型来代替氧限制模型，以检验该假设。(C)2009 Elsevier Inc. All rights reserved.
This study used an infusion of a paramagnetic contrast agent to perturb intravascular blood susceptibility and investigate its effect on the BOLD hemodynamic response. A three compartment BOLD signal model combined with a modified balloon model was developed to interpret the MR signal. This model incorporated arterial blood volume in order to simulate signal changes resulting from the contrast agent. The BOLD signal model was fitted to the experimental data to test the hypothesis that arterial blood volume changes during activation. It was found that allowing arterial blood volume to change, rather than assuming this change is negligible as often assumed in the literature, provides a better fit to the experimental data, particularly during the BOLD overshoot. The post-stimulus undershoot was fitted well, regardless of whether the arterial blood volume was allowed to change, by assuming that this feature is due to delayed venous compliance. However the resultant elevation in post-stimulus blood volume decays with an extremely long time constant, taking more than 55 s to recover to baseline following a 4.8 s stimulus. The post-stimulus signal changes measured here could alternatively be described by a post-stimulus elevation in metabolism. An alternative model of oxygen extraction, in place of the Oxygen Limitation model, would be required to test this hypothesis. (C) 2009 Elsevier Inc. All rights reserved.