On the origins of signal variance in FMRI of the human midbrain at high field.
On the origins of signal variance in FMRI of the human midbrain at high field.
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DOI：
10.1371/journal.pone.0062708
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Gore JC
中科院分区：
文献类型：
--
作者：
Barry RL;Coaster M;Rogers BP;Newton AT;Moore J;Anderson AW;Zald DH;Gore JC
与其他大脑区域相比，中脑中7特斯拉的功能性磁共振成像（fMRI）具有意想不到的低时间信噪比（TSNR）。在这项研究中使用的各种方法来定量识别噪声和信号差异的中脑功能磁共振成像数据的原因。使用RETROICOR、相位回归分析和呼吸和心脏频率范围内贡献的功率谱分析来检查生理噪声源的影响。使用一维（1-D）相位导航方法测试了3-D多激发序列中激发间相移的影响。此外，通过“不感兴趣”的回归分析，研究了与中脑（邻近白色物质和小脑前部）在时间上但在功能上相关的区域之间共享噪声影响的影响。这些降低噪声的尝试并没有改善中脑的整体TSNR。此外，在中脑和视觉皮层中测量稳态信号和噪声以获得静息状态数据。我们从中脑和皮层观察到了可比较的稳态信号。然而，中脑中的噪声相对于皮质高2-3倍，证实中脑中的低TSNR不是由于低信号而是由于大信号方差的结果。这些时间变化并不表现为已知的生理或其他噪声源，并且不能通过常规策略来减轻。在进一步的研究中，中脑的静息状态功能连接分析显示同源中脑区域之间存在强烈的内在波动。这些数据表明，中脑中的低TSNR可能源于与皮层相比由功能连接引起的更大的信号波动，而不是简单地反映生理噪声。
Functional Magnetic Resonance Imaging (fMRI) in the midbrain at 7 Tesla suffers from unexpectedly low temporal signal to noise ratio (TSNR) compared to other brain regions. Various methodologies were used in this study to quantitatively identify causes of the noise and signal differences in midbrain fMRI data. The influence of physiological noise sources was examined using RETROICOR, phase regression analysis, and power spectral analyses of contributions in the respiratory and cardiac frequency ranges. The impact of between-shot phase shifts in 3-D multi-shot sequences was tested using a one-dimensional (1-D) phase navigator approach. Additionally, the effects of shared noise influences between regions that were temporally, but not functionally, correlated with the midbrain (adjacent white matter and anterior cerebellum) were investigated via analyses with regressors of ‘no interest’. These attempts to reduce noise did not improve the overall TSNR in the midbrain. In addition, the steady state signal and noise were measured in the midbrain and the visual cortex for resting state data. We observed comparable steady state signals from both the midbrain and the cortex. However, the noise was 2–3 times higher in the midbrain relative to the cortex, confirming that the low TSNR in the midbrain was not due to low signal but rather a result of large signal variance. These temporal variations did not behave as known physiological or other noise sources, and were not mitigated by conventional strategies. Upon further investigation, resting state functional connectivity analysis in the midbrain showed strong intrinsic fluctuations between homologous midbrain regions. These data suggest that the low TSNR in the midbrain may originate from larger signal fluctuations arising from functional connectivity compared to cortex, rather than simply reflecting physiological noise.
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影响因子：
25
作者：
Buckholtz, Joshua W.;Treadway, Michael T.;Cowan, Ronald L.;Woodward, Neil D.;Benning, Stephen D.;Li, Rui;Ansari, M. Sib;Baldwin, Ronald M.;Schwartzman, Ashley N.;Shelby, Evan S.;Smith, Clarence E.;Cole, David;Kessler, Robert M.;Zald, David H.
通讯作者：
Zald, David H.
影响因子：
5.7
作者：
Barry, Robert L.;Strother, Stephen C.;Gatenby, J. Christopher;Gore, John C.
通讯作者：
Gore, John C.
影响因子：
3.3
作者：
HORNAK, JP;SZUMOWSKI, J;BRYANT, RG
通讯作者：
BRYANT, RG
影响因子：
5.7
作者：
Barry, Robert L.;Klassen, L. Martyn;Menon, Ravi S.
通讯作者：
Menon, Ravi S.
影响因子：
3.3
作者：
GRUETTER, R
通讯作者：
GRUETTER, R