Scouten A, Constable R T
Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA.
Magn Reson Med. 2007 Aug;58(2):306-15. doi: 10.1002/mrm.21273.
This work extends the multiple acquisitions with global inversion cycling vascular space occupancy (MAGIC VASO) method to human whole-brain functional magnetic resonance imaging (fMRI) at 3.0 Tesla and demonstrates the need to consider the dynamic contribution of cerebrospinal fluid (CSF) to the relative VASO signal change (DeltaVASO/VASO). Simulations were performed to determine the optimal slice number between global inversions, and correction factors were obtained to account for incomplete blood nulling in particular slices. The necessity of an accurate estimate of resting cerebral blood volume (CBV(rest)) is discussed in the context of DeltaCBV/CBV calculations. A three-compartment model is proposed to include both the resting and changing fractional CSF contribution (x(c,rest) and Deltax(c), respectively) to DeltaVASO/VASO. A MAGIC VASO sequence that provides whole-brain coverage is demonstrated using a paradigm comprised of visual, motor, and auditory stimulation. Activated regions are quantitatively compared in the corresponding blood oxygenation level-dependent (BOLD) images. Estimates of the minimum DeltaCBV/CBV resulting from motor and visual stimulation were comparable to previous findings at 17 +/- 8% (N = 8) and 19 +/- 9% (N = 6), respectively. The absence of VASO activation for auditory stimulation and evidence of activation-induced decreases in CSF volume fraction around the insula and superior temporal gyrus support the possibility of a Deltax(c) contribution to the VASO signal. Without specific knowledge of the CSF components (x(c,rest) and Deltax(c)), inference of DeltaCBV/CBV from DeltaVASO/VASO is severely limited.
这项工作将多采集全局反转循环血管空间占用（MAGIC VASO）方法扩展至3.0特斯拉的人类全脑功能磁共振成像（fMRI），并证明有必要考虑脑脊液（CSF）对相对VASO信号变化（DeltaVASO/VASO）的动态贡献。进行了模拟以确定全局反转之间的最佳切片数量，并获得校正因子以考虑特定切片中血液不完全归零的情况。在DeltaCBV/CBV计算的背景下讨论了准确估计静息脑血容量（CBV(rest)）的必要性。提出了一个三室模型，以纳入静息和变化的CSF分数贡献（分别为x(c,rest)和Deltax(c)）对DeltaVASO/VASO的影响。使用由视觉、运动和听觉刺激组成的范式展示了一种提供全脑覆盖的MAGIC VASO序列。在相应的血氧水平依赖（BOLD）图像中对激活区域进行了定量比较。运动和视觉刺激导致的最小DeltaCBV/CBV估计值分别与之前的研究结果相当，为17±8%（N = 8）和19±9%（N = 6）。听觉刺激未出现VASO激活，以及岛叶和颞上回周围激活诱导的CSF体积分数降低的证据支持了Deltax(c)对VASO信号有贡献的可能性。如果没有关于CSF成分（x(c,rest)和Deltax(c)）的具体知识，从DeltaVASO/VASO推断DeltaCBV/CBV会受到严重限制。
