Straubinger K, Schick F, Lutz O
Physikalisches Institut, Universität Tübingen, Germany.
MAGMA. 1998 Dec;7(2):88-94. doi: 10.1007/BF02592233.
The influence of pulse angle variations in the localization sequence stimulated echo acquisition mode (STEAM) on the signal of strongly coupled AB spin systems has been examined. Experimental 1H nuclear magnetic resonance (NMR) spectra of citrate were recorded on a 1.5 T whole-body imager. Theoretically calculated spectra were generated, with good correlation to experimental results. The dependence of the signal intensity on sequence timing and pulse angles was calculated analytically. For longer sequence timings, the ratio of the signal intensity from citrate to the signal intensity from uncoupled nuclei depends strongly on the applied flip angles. The shape of spectra also changes with varying flip angles. These effects are clearly less pronounced for STEAM than for point resolved spectroscopy (PRESS). The results have to be considered for quantitative measurements of citrate in spectroscopic investigations as, e.g. of prostate neoplasms.
研究了定位序列激发回波采集模式（STEAM）中的脉冲角度变化对强耦合AB自旋系统信号的影响。在1.5T全身成像仪上记录了柠檬酸盐的实验性1H核磁共振（NMR）谱。生成了理论计算谱，与实验结果具有良好的相关性。通过解析计算得出了信号强度对序列定时和脉冲角度的依赖性。对于较长的序列定时，柠檬酸盐信号强度与未耦合核信号强度之比强烈依赖于所施加的翻转角。谱的形状也随翻转角的变化而改变。与点分辨光谱法（PRESS）相比，这些效应在STEAM中明显不那么显著。在光谱研究中，如前列腺肿瘤的光谱研究中，进行柠檬酸盐定量测量时必须考虑这些结果。
