Anatomic localization and quantitative analysis of gradient refocused echo-planar fMRI susceptibility artifacts
Anatomic localization and quantitative analysis of gradient refocused echo-planar fMRI susceptibility artifacts
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DOI：
10.1006/nimg.1997.0289
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发表时间：
1997-10-01
期刊：
影响因子：
5.7
通讯作者：
Conturo, TE
中科院分区：
文献类型：
--
作者：
Ojemann, JG;Akbudak, E;Conturo, TE
功能磁共振成像（fMRI）技术，如回声平面成像，可以快速、灵敏、全脑测量局部血液如何在认知范式中引起MR信号变化。由于氧代谢方式和氧代谢不匹配导致的血氧变化导致微观敏感性效应的动态变化，导致fMRI技术测量血氧水平依赖（BOLD）信号。已知相关的静态宏观易感性效应会引起伪影，使MR信号衰减，导致与骨窦和空气窦相邻的大脑某些区域出现“盲点”。对于常见的全脑功能磁共振成像技术，对信号丢失伪影的解剖位置、空间范围和大小进行了量化。在4名健康志愿者中进行静息梯度回声EPI研究。信号丢失主要局限于双侧额叶下区（眶内回和直回）和颞叶下外侧（包括部分梭状回）。增加的回波时间（TE）均匀地产生较大的伪影。获取的切片的方向和相位编码方向的选择会影响伪影的位置、形状和程度。具有严重伪影的大脑区域可能具有衰减的激活信号，这对针对这些区域激活的fMRI研究的设计和解释具有潜在的影响。(C) 1997学术出版社。
Functional magnetic resonance imaging (fMRI) techniques, such as echo-planar imaging, can permit rapid, sensitive, whole-brain measurements of local blood how-induced MR signal changes seen during cognitive paradigms. Changes in blood oxygenation due to mismatch of how and oxygen metabolism cause dynamic variations in microscopic susceptibility effects, leading to the blood oxygenation level-dependent (BOLD) signal measured by fMRI techniques. A related static macroscopic susceptibility effect is known to cause artifacts that attenuate the MR signal, leading to ''blind spots'' in some regions of brain adjacent to bone and air sinuses, The anatomical location, spatial extent, and magnitude of signal loss artifact are quantitated for a common whole-brain fMRI technique. Resting gradient-echo EPI studies were obtained in four healthy volunteers. Signal loss was primarily localized to inferior frontal regions (medial orbital gyri and gyrus rectus) and to inferior lateral temporal lobe (including part of fusiform gyrus) bilaterally. Increased echo time (TE) uniformly produced larger artifacts. The orientation of acquired slices and choice of phase-encoding direction influenced the location, shape, and extent of the artifacts. Regions of the brain with severe artifact may have attenuated activation signal, with potential implications for the design and interpretation of fMRI studies targeting activations in these areas. (C) 1997 Academic Press.