van Gelderen Peter, W H Wu Carolyn, de Zwart Jacco A, Cohen Leonardo, Hallett Mark, Duyn Jeff H
Advanced MRI, National Institutes of Health, Bethesda, Maryland 20892-1065, USA.
Magn Reson Med. 2005 Sep;54(3):569-76. doi: 10.1002/mrm.20577.
Visual and somatosensory activation studies were performed on normal subjects to compare the spatial discrimination and reproducibility between functional MRI (fMRI) methods based on blood oxygen level-dependent (BOLD) and perfusion contrast. To allow simultaneous measurement of BOLD and perfusion contrast, a dedicated MRI acquisition technique was developed. Repeated experiments of sensory stimulation of single digits of the right hand showed an average variability of activation amplitude of 25% for BOLD data, and a significantly lower variability of 21% for perfusion data. No significant difference in the variability of the locus of activity was observed between the BOLD and perfusion data. In somatotopy experiments, digits II and V were subjected to passive sensory stimulation. Both the BOLD and perfusion data showed substantial overlap in the activation patterns from the two digits. In a retinotopy study, two stimuli were alternated to excite different patches of V1. Again there was substantial overlap between the activation patterns from both stimuli, although the perfusion performed somewhat better than the BOLD method. Particularly for the visual studies, the overlap in activation patterns was more than expected based on the fine-scale retinotopic mapping of cortical activity, suggesting that both BOLD and perfusion contrast mechanisms contribute substantially to the point-spread function (PSF).
对正常受试者进行了视觉和体感激活研究，以比较基于血氧水平依赖（BOLD）和灌注对比的功能磁共振成像（fMRI）方法之间的空间辨别能力和可重复性。为了同时测量BOLD和灌注对比，开发了一种专用的MRI采集技术。对右手单个手指进行感觉刺激的重复实验表明，BOLD数据的激活幅度平均变异性为25%，而灌注数据的变异性显著较低，为21%。在BOLD和灌注数据之间，未观察到活动位点变异性的显著差异。在躯体定位实验中，对食指和小指进行被动感觉刺激。BOLD和灌注数据均显示来自这两个手指的激活模式有大量重叠。在视网膜定位研究中，交替使用两种刺激来激发V1的不同区域。同样，两种刺激的激活模式之间有大量重叠，尽管灌注比BOLD方法表现稍好。特别是对于视觉研究，基于皮质活动的精细视网膜定位映射，激活模式的重叠比预期的更多，这表明BOLD和灌注对比机制都对点扩散函数（PSF）有很大贡献。
