Weckesser M, Posse S, Olthoff U, Kemna L, Dager S, Müller-Gärtner H W
Institute of Medicine, Research Center Jülich, Germany. m.weckesser(fz-juelich.de.
Magn Reson Med. 1999 Jan;41(1):213-6. doi: 10.1002/(sici)1522-2594(199901)41:1<213::aid-mrm31>3.0.co;2-s.
Hypocapnia due to hyperventilation reduces cerebral blood flow and volume. To investigate the effects of hyperventilation on the regional signal response to visual activation using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI), six volunteers were investigated during visual stimulation under normocapnia and hypocapnia conditions. Hyperventilation significantly decreased in visual cortex the BOLD MRI response to visual stimulation (3.97+/-0.5% [mean ( SD) in normocapnia vs. 0.77+/-0.7% in hypocapnia, P < 0.01]. In three of six subjects, functional signal changes were reduced to noise level. The reduced stimulus response during hyperventilation is probably due to a decreased overshoot in the blood oxygenation response. These results indicate that BOLD-contrast functional MRI is highly sensitive to pCO2 changes.
过度通气引起的低碳酸血症会减少脑血流量和脑血容量。为了使用血氧水平依赖（BOLD）磁共振成像（MRI）研究过度通气对视觉激活区域信号反应的影响，对6名志愿者在正常碳酸血症和低碳酸血症条件下进行视觉刺激时进行了研究。过度通气显著降低了视觉皮层对视觉刺激的BOLD MRI反应（正常碳酸血症时为3.97±0.5%[平均值（标准差）]，低碳酸血症时为0.77±0.7%，P<0.01）。在6名受试者中的3名中，功能信号变化降低到噪声水平。过度通气期间刺激反应降低可能是由于血氧反应的过冲减少。这些结果表明，BOLD对比功能MRI对pCO2变化高度敏感。
