The functional magnetic resonance imaging (fMRI) at ultra-high field (UHF, $\geqslant 7\text{T}$ ) is a powerful temporal acquisition method which promises to capture neuronal activities at submillimeter scale. But high-spatial-resolution fMRI still remains difficult, as the nuisance temporal noise which also grows with the main magnetic field strength. For decades, mainstream solutions in reducing motion-induced temporal noise include motion-correction algorithms in image post-processing as well as MR acquisition schemes in RF pulse sequence designs, however hardware-related studies have been rarely reported over the RF receive coil. In this study, we have proposed the intrinsic temporal performance model, which is specifically used for measuring coil-related intrinsic temporal SNR (tSNR*), and the intrinsic sensitivity variability and thermal noise variability have been proposed as model parameters. The intrinsic temporal performance of single-channel loops and array coils were evaluated using numerical electromagnetic simulations, and phantom experiments were designed to investigate the intrinsic thermal noise variability. It was observed that the achievable intrinsic tSNR* can be greatly lowered by ~90% even with 2 mm translational motion in the normal direction, suggesting the effect of RF receive coils in producing temporal noise. The proposed model provides a new perspective in optimizing coil designs and array coil temporal combination methods, which may offer a feasible means in achieving submillimeter resolutions at UHF. Moreover, model parameters from the intrinsic temporal performance model can be directly calculated based on single MRI acquisition, offering a practical performance metric for manufactures and customers in quality and assurance checks of RF receive coil products.

中文翻译：

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磁共振成像中射频接收线圈的固有时间性能

超高场（UHF、 $\geqslant 7\文本{T}$ ) 是一种强大的时间采集方法，有望捕获亚毫米级的神经元活动。但是高空间分辨率的 fMRI 仍然很困难，因为令人讨厌的时间噪声也会随着主磁场强度的增加而增加。几十年来，减少运动引起的时间噪声的主流解决方案包括图像后处理中的运动校正算法以及射频脉冲序列设计中的 MR 采集方案，但很少有关于射频接收线圈的硬件相关研究的报道。在本研究中，我们提出了固有时间性能模型，该模型专门用于测量与线圈相关的固有时间信噪比 (tSNR*)，并提出了固有灵敏度变异性和热噪声变异性作为模型参数。使用数值电磁仿真评估单通道环路和阵列线圈的固有时间性能，并设计了幻影实验来研究固有热噪声可变性。据观察，即使在正常方向上有 2 毫米的平移运动，可实现的固有 tSNR* 也可以大大降低约 90%，这表明射频接收线圈在产生时间噪声方面的影响。所提出的模型为优化线圈设计和阵列线圈时间组合方法提供了新的视角，这可能为在 UHF 下实现亚毫米分辨率提供一种可行的手段。此外，可以基于单次 MRI 采集直接计算来自固有时间性能模型的模型参数，