1 School of Kinesiology, The University of Western Ontario, London, ON, Canada.
2 Robarts Research Institute, The University of Western Ontario, London, ON, Canada.
J Cereb Blood Flow Metab. 2019 Jul;39(7):1204-1214. doi: 10.1177/0271678X18762880. Epub 2018 Mar 7.
The larger intracranial conduit vessels contribute to the total cerebral vascular resistance, and understanding their vasoreactivity to physiological stimuli is required when attempting to understand regional brain perfusion. Reactivity of the larger cerebral conduit arteries remains understudied due to a need for improved imaging methods to simultaneously assess these vessels in a single stimulus. We characterized reactivity of basal intracranial conduit arteries (basilar, right and left posterior, middle and anterior cerebral arteries) and the right and left internal carotid arteries, to manipulations in end-tidal CO (PetCO). Cross-sectional area changes (%CSA) were evaluated from high-resolution (0.5 mm isotropic) images collected at 7 T using a T1-weighted 3D SPACE pulse sequence, providing high contrast between vessel lumen and surrounding tissue. Cerebrovascular reactivity was calculated as %CSA/ΔPetCO in eight healthy individuals (18-23 years) during normocapnia (41 ± 4 mmHg), hypercapnia (48 ± 4 mmHg; breathing 5% CO, balance oxygen), and hypocapnia (31 ± 8 mmHg; via hyperventilation). Reactivity to hypercapnia ranged from 0.8%/mmHg in the right internal carotid artery to 2.7%/mmHg in the left anterior cerebral artery. During hypocapnia, vasoconstriction ranged from 0.9%/mmHg in the basilar artery to 2.6%/mmHg in the right posterior cerebral artery. Heterogeneous cerebrovascular reactivity to hypercapnia and hypocapnia was characterized across basal intracranial conduit and internal carotid arteries.
较大的颅内导血管对总脑血管阻力有贡献，当试图了解局部脑灌注时，需要了解它们对生理刺激的血管反应性。由于需要改进成像方法来在单次刺激中同时评估这些血管，因此较大的大脑导动脉的反应性仍然研究不足。我们描述了基底颅内导血管（基底动脉、右侧和左侧后交通动脉、大脑中动脉和大脑前动脉）和右侧和左侧颈内动脉对呼气末 CO（PetCO）变化的反应性。使用 T1 加权 3D SPACE 脉冲序列从 7T 采集的高分辨率（0.5mm 各向同性）图像中评估横截面面积变化（%CSA），提供了血管内腔和周围组织之间的高对比度。在 8 名健康个体（18-23 岁）中，在正常碳酸血症（41±4mmHg）、高碳酸血症（48±4mmHg；呼吸 5%CO，平衡氧气）和低碳酸血症（31±8mmHg；通过过度通气）期间，通过%CSA/ΔPetCO 计算脑血管反应性。右侧颈内动脉的反应性范围为 0.8%/mmHg，左侧大脑前动脉的反应性范围为 2.7%/mmHg。在低碳酸血症期间，从基底动脉的 0.9%/mmHg 到右侧后交通动脉的 2.6%/mmHg ，血管收缩范围不同。基底颅内导血管和颈内动脉对高碳酸血症和低碳酸血症的脑血管反应性存在异质性。
