Turner R, Jezzard P, Wen H, Kwong K K, Le Bihan D, Zeffiro T, Balaban R S
Laboratory of Cardiac Energetics, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.
Magn Reson Med. 1993 Feb;29(2):277-9. doi: 10.1002/mrm.1910290221.
The effects of photic stimulation on the visual cortex of human brain were studied by means of gradient-echo echo-planar imaging (EPI). Whole-body 4 and 1.5 T MRI systems, equipped with a small z axis head gradient coil, were used. Variations of image intensity of up to 28% at 4 T, and up to 7% at 1.5 T, were observed in primary visual cortex, corresponding to an increase of blood oxygenation in regions of increased neural activity. The larger effects at 4 T are due to the increased importance of the susceptibility difference between deoxygenated and oxygenated blood at high fields.
采用梯度回波平面回波成像（EPI）技术研究了光刺激对人脑视觉皮层的影响。使用配备小z轴头部梯度线圈的全身4T和1.5T磁共振成像（MRI）系统。在初级视觉皮层观察到，4T时图像强度变化高达28%，1.5T时高达7%，这对应于神经活动增强区域血液氧合的增加。4T时效应更大是由于在高场下脱氧和氧合血液之间的磁化率差异的重要性增加。
