Schmidt Conny F, Boesiger Peter, Ishai Alumit
Institute for Biomedical Engineering, University of Zurich and Swiss Federal Institute of Technology, Switzerland.
Neuroimage. 2005 Jul 1;26(3):852-9. doi: 10.1016/j.neuroimage.2005.02.043. Epub 2005 Apr 8.
In this study, we compared fMRI activation measured with gradient- and spin-echo-based fMRI during visual perception of faces, which is mediated by neural activation within a distributed cortical network. With both fMRI techniques, bilateral activation was observed in multiple regions including the inferior occipital gyrus, fusiform gyrus, superior temporal sulcus, amygdala, inferior frontal gyrus, and orbitofrontal cortex. When compared with the gradient-echo sequence, activation measured with the spin-echo sequence was significantly reduced. This decrease was manifested by smaller cluster size, lower statistical significance, smaller amplitude of the fMRI signal, and smaller number of subjects who showed activation in all face-responsive regions. In orbitofrontal cortex, a region prone to susceptibility-related signal dephasing, the spin-echo acquisition considerably restored the signal, but did not reveal stronger activation when compared with the gradient-echo acquisition. Our data indicate that optimized GE sequences that reduce susceptibility artefacts are sufficient to detect activation in regions such as the orbitofrontal cortex.
在本研究中，我们比较了基于梯度回波和自旋回波的功能磁共振成像（fMRI）在面部视觉感知过程中测量到的激活情况，面部视觉感知由分布式皮质网络内的神经激活介导。使用这两种fMRI技术时，在多个区域观察到双侧激活，包括枕下回、梭状回、颞上沟、杏仁核、额下回和眶额皮质。与梯度回波序列相比，自旋回波序列测量到的激活显著降低。这种降低表现为簇大小更小、统计显著性更低、fMRI信号幅度更小以及在所有面部反应区域均显示激活的受试者数量更少。在眶额皮质这个容易出现与易感性相关信号失相的区域，自旋回波采集相当程度地恢复了信号，但与梯度回波采集相比并未显示出更强的激活。我们的数据表明，优化后的可减少易感性伪影的梯度回波序列足以检测眶额皮质等区域的激活。
