Mangia Silvia, Tkác Ivan, Gruetter Rolf, Van De Moortele Pierre-Francois, Giove Federico, Maraviglia Bruno, Uğurbil Kâmil
Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN 55455, USA.
Magn Reson Imaging. 2006 May;24(4):343-8. doi: 10.1016/j.mri.2005.12.023. Epub 2006 Feb 23.
Proton magnetic resonance spectroscopy (1H-MRS) has been used in a number of studies to noninvasively assess the temporal changes of lactate in the activated human brain. However, the results have not been consistent. The aim of the present study was to test the sensitivity of 1H-MRS during functional experiments at the highest magnetic field currently available for human studies (7 T). Stability and reproducibility of the measurements were evaluated from LCModel analysis of time series of spectra measured during a visual stimulation paradigm and by examination of the difference between spectra obtained at rest and during activation. The sensitivity threshold to detect concentration changes was 0.2 micromol/g for most of the quantified metabolites. The possible variations of metabolite concentrations during visual stimulation were within the same range (+/-0.2 micromol/g). In addition, the influence of a small line-narrowing effect due to the blood oxygenation level-dependent (BOLD) T2* changes on the estimated concentrations was simulated. Quantification of metabolites was, in general, not affected beyond 1% by line-width changes within 0.5 Hz.
质子磁共振波谱（1H-MRS）已在多项研究中用于无创评估激活的人脑中乳酸的时间变化。然而，结果并不一致。本研究的目的是在目前可用于人体研究的最高磁场（7T）下的功能实验中测试1H-MRS的灵敏度。通过对视觉刺激范式期间测量的光谱时间序列进行LCModel分析，并检查静息和激活期间获得的光谱之间的差异，评估测量的稳定性和可重复性。对于大多数定量代谢物，检测浓度变化的灵敏度阈值为0.2微摩尔/克。视觉刺激期间代谢物浓度的可能变化在相同范围内（±0.2微摩尔/克）。此外，还模拟了由于血氧水平依赖性（BOLD）T2*变化引起的小线宽变窄效应对估计浓度的影响。一般来说，线宽在0.5Hz以内的变化对代谢物定量的影响不超过1%。
