SIGNAL AND NOICE CHARACTERISTICS OF HAHN SE AND GE BOLD FMRI AT 7T IN HUMANS

HAHN SE 和 GE BOLD FMRI 在 7T 下人体中的信号和噪音特征

• 批准号: 7601625
• 负责人: ESSA YACOUB
• 金额: $ 10.63万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7601625
• 关键词: Area; Characteristics; Computer Retrieval of Information on Scientific Projects Database; Data; Functional Magnetic Resonance Imaging; Funding; Grant; Human; Image; Institution; Methods; Noise; Physiological Processes; Research; Research Personnel; Resolution; Resources; Series; Signal Transduction; Source; Standards of Weights and Measures; Time; Tissues; United States National Institutes of Health; magnetic field; millimeter; size

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. At very high magnetic fields, GE BOLD fMRI is expected to contain nonspecific contributions and behave differently than HSE fMRI data. Similarly, the two approaches can conceivably suffer from different contributions to temporal instabilities in a times series that ultimately determine the contrast-to-noise ratio (CNR). We investigate the signal and signal fluctuation characteristics in GE and HSE fMRI data with the imaging parameters separately optimized for each contrast at 7 T. In HSE fMRI, activation-induced fractional signal change (DeltaS/S) decreased rapidly, and the ratio of standard deviations of image-to-image fluctuations due to physiological processes (sigmaPhys) to thermal noise (sigmaTherm) remained constant with increasing voxel volume. In contrast, DeltaS/S as well as volume of activated voxels was virtually independent of voxel size for GE BOLD, and sigma(Phys)/sigmaTherm increased with increasing voxel size. The ratio of BOLD signal changes (GE/HSE) was much closer to 1 in tissue areas compared to vessel areas. These observations led to the conclusions that the spatial extent of the activation-induced DeltaS/S was much broader in the GE data, and that the physiological processes that give rise to the temporal fluctuations lost coherence over millimeter distances in HSE compared to GE fMRI data. While further studies are needed to characterize it fully, sigmaPhys in HSE data was clearly different than in GE data. It was concluded that HSE imaging yields a significantly reduced amount of nonspecific signals compared to GE imaging, and, would be the method of choice (over GE) for high-resolution applications in humans.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 在非常高的磁场下，GE BOLD fMRI 预计会包含非特异性贡献，并且表现与 HSE fMRI 数据不同。同样，可以想象，这两种方法可能会受到时间序列中时间不稳定性的不同影响，而时间序列最终决定了对比度噪声比 (CNR)。我们研究了 GE 和 HSE fMRI 数据中的信号和信号波动特征，并针对 7 T 下的每个对比度分别优化了成像参数。在 HSE fMRI 中，激活引起的分数信号变化 (DeltaS/S) 迅速下降，并且由于生理过程 (sigmaPhys) 与热噪声 (sigmaTherm) 导致的图像间波动的标准差之比保持恒定 增加体素体积。相比之下，对于 GE BOLD，DeltaS/S 以及激活体素的体积实际上与体素大小无关，并且 sigma(Phys)/sigmaTherm 随着体素大小的增加而增加。与血管区域相比，组织区域中的 BOLD 信号变化比率 (GE/HSE) 更接近 1。这些观察得出的结论是，GE 数据中激活引起的 DeltaS/S 的空间范围要宽得多，并且与 GE fMRI 数据相比，HSE 中引起时间波动的生理过程在毫米距离上失去了一致性。虽然需要进一步研究来充分表征，但 HSE 数据中的 sigmaPhys 与 GE 数据中的明显不同。结论是，与 GE 成像相比，HSE 成像产生的非特异性信号量显着减少，并且将成为人类高分辨率应用的首选方法（相对于 GE）。