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: 7721347
• 负责人: ESSA YACOUB
• 金额: $ 8.92万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7721347
• 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.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 在非常高的磁场下，GE BOLD fMRI预计将包含非特异性贡献，并且表现出与HSE fMRI数据不同的行为。同样，这两种方法可以想象地遭受不同的贡献，最终确定的对比度噪声比（CNR）的时间序列中的时间不稳定性。我们研究了GE和HSE fMRI数据的信号和信号波动特性，分别优化了成像参数，为每种对比度在7 T。在HSE fMRI中，激活诱导的分数信号变化（DeltaS/S）迅速下降，并且由于生理过程（sigmaPhys）与热噪声（sigmaTherm）引起的图像到图像波动的标准差的比率随着体素体积的增加而保持恒定。相比之下，DeltaS/S以及激活体素的体积几乎与GE BOLD的体素大小无关，并且sigma（Phys）/sigmaTherm随着体素大小的增加而增加。BOLD信号变化的比率（GE/HSE）在组织区域中比在血管区域中更接近1。这些观察结果得出的结论是，GE数据中激活诱导的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。虽然需要进一步的研究来充分表征它，但HSE数据中的sigmaPhys与GE数据明显不同。得出的结论是，与GE成像相比，HSE成像产生的非特异性信号量显著减少，并且将是人类高分辨率应用的首选方法（超过GE）。