Department of Medical Imaging, University of Western Ontario, London, Canada.
Division of Neuroradiology, Joint Department of Medical Imaging, University Health Network, Toronto, Canada.
J Magn Reson Imaging. 2017 Nov;46(5):1448-1455. doi: 10.1002/jmri.25639. Epub 2017 Feb 2.
Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is a technique used to infer neuronal activity from the observed changes in blood flow. Cerebrovascular reactivity (CVR) is the ability of arterioles to increase blood flow in response to vasodilatory stimulus. We hypothesize that in areas of disease where there is exhausted vascular reserve and impaired CVR there will be diminished blood flow response following neuronal activation, and that these areas would appear as false-negative tests on BOLD fMRI.
Patients with steno-occlusive disease and unilateral hemodynamic impairment received a standardized hypercapnic stimuli while being imaged with BOLD fMRI to generate CVR maps. These were compared to traditional BOLD fMRI maps of neuronal activation in the motor cortex in response to a motor task.
Neuronal activation from the motor task was found to be linearly correlated with CVR (n = 11 patients, R = 0.82). Regions with positive (normal) CVR showed positive activation on BOLD fMRI, while regions with negative CVR had attenuated neuronal activation on BOLD fMRI.
In areas with cerebrovascular disease where CVR is impaired, there is uncoupling of neuronal activation and blood flow that confounds traditional BOLD fMRI. CVR mapping is a noninvasive MRI-based imaging technique that can provide information about the vascular reactivity of the brain that is important to consider when interpreting traditional BOLD fMRI studies.
2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1448-1455.
血氧水平依赖（BOLD）功能磁共振成像（fMRI）是一种从观察到的血流变化推断神经元活动的技术。脑血管反应性（CVR）是小动脉在血管扩张刺激下增加血流量的能力。我们假设，在疾病区域，血管储备耗尽，CVR 受损，神经元激活后血流量的反应会减弱，这些区域在 BOLD fMRI 上会呈现假阴性测试。
患有狭窄-阻塞性疾病和单侧血液动力学障碍的患者在接受 BOLD fMRI 成像时接受了标准化的高碳酸血症刺激，以生成 CVR 图。这些与运动皮层中神经元激活的传统 BOLD fMRI 图进行了比较，以响应运动任务。
发现运动任务的神经元激活与 CVR 呈线性相关（n=11 例患者，R=0.82）。具有正（正常）CVR 的区域在 BOLD fMRI 上显示出阳性激活，而具有负 CVR 的区域在 BOLD fMRI 上显示出神经元激活减弱。
在 CVR 受损的脑血管疾病区域，神经元激活与血流之间存在解耦，这会混淆传统的 BOLD fMRI。CVR 映射是一种基于 MRI 的非侵入性成像技术，可以提供有关大脑血管反应性的信息，这在解释传统的 BOLD fMRI 研究时非常重要。
2 技术功效：第 3 阶段 J. Magn. Reson. Imaging 2017;46:1448-1455.
