Pattany P M, Massand M G, Bowen B C, Quencer R M
Department of Radiology, University of Miami School of Medicine, Miami, FL 33136, USA.
AJNR Am J Neuroradiol. 2006 May;27(5):1070-3.
Although single-voxel proton MR spectroscopy is a noninvasive method that enables measurement of brain metabolite concentrations, it has been shown that physiologic brain motion causes inaccuracies in measurement of metabolite concentrations and increases the overall SD of the measurements when the stimulated echo acquisition mode (STEAM) is used. We tested the hypothesis that the point-resolved spectroscopy (PRESS) technique is less sensitive to physiologic brain motion than the STEAM technique.
In 10 healthy subjects, spectra were obtained from a voxel located in the left basal ganglia by using the PRESS sequence with cardiac gating and without water suppression to assess global phase change as a function of physiologic brain motion. This was accomplished by acquiring data at various time delays from the R wave throughout the cardiac cycle. Subsequently, spectra were obtained in 10 healthy subjects by using PRESS both without and with cardiac gating, and with water suppression, to determine whether brain motion resulted in a statistically significant difference in mean and SD of measured metabolite concentration.
At various time delays from the R wave throughout the cardiac cycle, no significant global phase difference was noted in water signal intensity. In addition, when PRESS data were obtained both without and with cardiac gating (by using an optimal delay obtained from previously published data by using STEAM), no significant difference was seen in measured metabolite concentrations and SDs.
The PRESS technique is relatively insensitive to physiologic brain motion.
尽管单体素质子磁共振波谱是一种能够测量脑代谢物浓度的非侵入性方法，但已表明，当使用刺激回波采集模式（STEAM）时，生理性脑运动可导致代谢物浓度测量不准确，并增加测量的总体标准差。我们检验了以下假设：点分辨波谱（PRESS）技术比STEAM技术对生理性脑运动的敏感性更低。
对10名健康受试者，通过使用带心脏门控且不进行水抑制的PRESS序列，从位于左侧基底神经节的一个体素获取波谱，以评估作为生理性脑运动函数的整体相位变化。这是通过在整个心动周期中从R波开始的不同时间延迟采集数据来实现的。随后，对10名健康受试者，分别在不使用和使用心脏门控以及进行水抑制的情况下使用PRESS获取波谱，以确定脑运动是否导致所测代谢物浓度的均值和标准差出现统计学显著差异。
在整个心动周期中从R波开始的不同时间延迟时，水信号强度未观察到显著的整体相位差异。此外，当分别在不使用和使用心脏门控（通过使用先前发表的STEAM数据获得的最佳延迟）的情况下获取PRESS数据时，所测代谢物浓度和标准差未见显著差异。
PRESS技术对生理性脑运动相对不敏感。
