Susceptibility-induced loss of signal: Comparing PET and fMRI on a semantic task
Susceptibility-induced loss of signal: Comparing PET and fMRI on a semantic task
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DOI：
10.1006/nimg.2000.0595
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发表时间：
2000-06-01
期刊：
影响因子：
5.7
通讯作者：
Tyler, LK
中科院分区：
文献类型：
--
作者：
Devlin, JT;Russell, RP;Tyler, LK
功能磁共振成像（fMRI）已成为研究认知活动的神经关联的一种流行工具。然而，功能磁共振成像的一个限制是，由于宏观磁化率效应的扭曲，在高磁场强度下变得更加严重，它难以成像靠近组织界面的区域。这种困难对于涉及到靠近充满空气的鼻窦的颞叶区域的语言任务来说尤其成问题。本文研究了颞叶中易感性引起的信号损失，并提出通过定义感兴趣的先验区域，并使用K. J. Worsley， S. Marrett， P. Neelin, a . C. Vandal， K. J. Friston和a . C. Evans (1996, Hum。大脑地图。4:58-83)，这些区域的激活有时可以通过增加分析的统计能力来检测。我们进行了两个实验，一个是PET，另一个是fMRI，使用几乎相同的语义分类范式和类似的分析方法。PET和fMRI结果有重叠和不同的地方。在fMRI数据集的初步分析中，一个预期的差异是颞叶中两个区域缺乏激活。然而，对于感兴趣的特定区域，检测到其中一个区域的激活。这些实验证明了三点：第一，即使对于几乎相同的认知任务，比如本研究中的任务，PET和fMRI也可能产生不同的结果；其次，由于fMRI中宏观敏感性伪影，两种方法之间的差异可以通过适当的统计校正来克服，但只能部分克服；第三，如果要提高fMRI实验对颞叶激活的敏感性，就需要新的数据采集范式来充分处理敏感性引起的信号损失。(C) 2000年学术出版社。
Functional magnetic resonance imaging (fMRI) has become a popular tool for investigations into the neural correlates of cognitive activity. One limitation of fMRI, however, is that it has difficulty imaging regions near tissue interfaces due to distortions from macroscopic susceptibility effects which become more severe at higher magnetic field strengths. This difficulty can be particularly problematic for language tasks that engage regions of the temporal lobes near the air-filled sinuses. This paper investigates susceptibility-induced signal loss in the temporal lobes and proposes that by defining a priori regions of interest and using the small-volume statistical correction of K. J. Worsley, S. Marrett, P. Neelin, A. C. Vandal, K. J. Friston, and A. C. Evans (1996, Hum. Brain Mapp. 4: 58-83), activations in these areas can sometimes be detected by increasing the statistical power of the analysis. We conducted two experiments, one with PET and the other with fMRI, using almost identical semantic categorization paradigms and comparable methods of analysis. There were areas of overlap as well as differences between the PET and fMRI results. One anticipated difference was a lack of activation in two regions in the temporal lobe on initial analyses in the fMRI data set. With a specific region of interest, however, activation in one of the regions was detected. These experiments demonstrate three points: first, even for almost identical cognitive tasks such as those in this study, PET and fMRI may not produce identical results; second, differences between the two methods due to macroscopic susceptibility artifacts in fMRI can be overcome with appropriate statistical corrections, but only partially; and third, new data acquisition paradigms are necessary to fully deal with susceptibility-induced signal loss if the sensitivity of the fMRI experiment to temporal lobe activations is to be enhanced. (C) 2000 Academic Press.