Stickland Rachael C, Zvolanek Kristina M, Moia Stefano, Caballero-Gaudes César, Bright Molly G
Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States.
Front Neurosci. 2022 Jun 15;16:910025. doi: 10.3389/fnins.2022.910025. eCollection 2022.
Cerebrovascular reactivity (CVR), an important indicator of cerebrovascular health, is commonly studied with the Blood Oxygenation Level Dependent functional MRI (BOLD-fMRI) response to a vasoactive stimulus. Theoretical and empirical evidence suggests that baseline cerebral blood flow (CBF) modulates BOLD signal amplitude and may influence BOLD-CVR estimates. We address how acquisition and modeling choices affect the relationship between baseline cerebral blood flow (bCBF) and BOLD-CVR: whether BOLD-CVR is modeled with the inclusion of a breathing task, and whether BOLD-CVR amplitudes are optimized for hemodynamic lag effects. We assessed between-subject correlations of average GM values and within-subject spatial correlations across cortical regions. Our results suggest that a breathing task addition to a resting-state acquisition, alongside lag-optimization within BOLD-CVR modeling, can improve BOLD-CVR correlations with bCBF, both between- and within-subjects, likely because these CVR estimates are more physiologically accurate. We report positive correlations between bCBF and BOLD-CVR, both between- and within-subjects. The physiological explanation of this positive correlation is unclear; research with larger samples and tightly controlled vasoactive stimuli is needed. Insights into what drives variability in BOLD-CVR measurements and related measurements of cerebrovascular function are particularly relevant when interpreting results in populations with altered vascular and/or metabolic baselines or impaired cerebrovascular reserve.
脑血管反应性（CVR）是脑血管健康的一个重要指标，通常通过对血管活性刺激的血氧水平依赖性功能磁共振成像（BOLD-fMRI）反应来研究。理论和实证证据表明，基线脑血流量（CBF）会调节BOLD信号幅度，并可能影响BOLD-CVR估计值。我们探讨了采集和建模选择如何影响基线脑血流量（bCBF）与BOLD-CVR之间的关系：BOLD-CVR是否在纳入呼吸任务的情况下进行建模，以及BOLD-CVR幅度是否针对血流动力学滞后效应进行了优化。我们评估了平均灰质（GM）值的受试者间相关性以及皮质区域内的受试者内空间相关性。我们的结果表明，在静息状态采集时加入呼吸任务，以及在BOLD-CVR建模中进行滞后优化，可以改善bCBF与BOLD-CVR在受试者间和受试者内的相关性，这可能是因为这些CVR估计在生理上更准确。我们报告了bCBF与BOLD-CVR在受试者间和受试者内均呈正相关。这种正相关的生理学解释尚不清楚；需要对更大样本和严格控制的血管活性刺激进行研究。当解释血管和/或代谢基线改变或脑血管储备受损人群的结果时，深入了解驱动BOLD-CVR测量及相关脑血管功能测量变异性的因素尤为重要。
