Williams Rebecca J, McMahon Katie L, Hocking Julia, Reutens David C
University of Queensland, Centre for Advanced Imaging, Brisbane, Australia; University of Queensland, Queensland Brain Institute, Brisbane, Australia.
J Magn Reson Imaging. 2014 Aug;40(2):367-75. doi: 10.1002/jmri.24353. Epub 2013 Oct 29.
To compare diffusion-weighted functional magnetic resonance imaging (DfMRI), a novel alternative to the blood oxygenation level-dependent (BOLD) contrast, in a functional MRI experiment.
Nine participants viewed contrast reversing (7.5 Hz) black-and-white checkerboard stimuli using block and event-related paradigms. DfMRI (b = 1800 mm/s(2)) and BOLD sequences were acquired. Four parameters describing the observed signal were assessed: percent signal change, spatial extent of the activation, the Euclidean distance between peak voxel locations, and the time-to-peak of the best fitting impulse response for different paradigms and sequences.
The BOLD conditions showed a higher percent signal change relative to DfMRI; however, event-related DfMRI showed the strongest group activation (t = 21.23, P < 0.0005). Activation was more diffuse and spatially closer to the BOLD response for DfMRI when the block design was used. DfMRIevent showed the shortest TTP (4.4 ± 0.88 sec).
The hemodynamic contribution to DfMRI may increase with the use of block designs.
在一项功能磁共振成像实验中，比较扩散加权功能磁共振成像（DfMRI）这一血氧水平依赖（BOLD）对比的新型替代方法。
9名参与者使用组块和事件相关范式观看对比度反转（7.5赫兹）的黑白棋盘格刺激。采集DfMRI（b = 1800毫米/秒²）和BOLD序列。评估了描述观察到的信号的四个参数：信号变化百分比、激活的空间范围、峰值体素位置之间的欧几里得距离以及不同范式和序列的最佳拟合脉冲响应的峰值时间。
相对于DfMRI，BOLD条件显示出更高的信号变化百分比；然而，事件相关的DfMRI显示出最强的组激活（t = 21.23，P < 0.0005）。当使用组块设计时，DfMRI的激活更分散且在空间上更接近BOLD响应。DfMRI事件显示出最短的峰值时间（4.4 ± 0.88秒）。
使用组块设计时，血流动力学对DfMRI的贡献可能会增加。
