MR Research Group, Department of Diagnostic and Interventional Neuroradiology, University Hospital Tuebingen, Hoppe-Seyler strasse 3, 72076 Tuebingen, Germany.
J Magn Reson. 2011 Sep;212(1):55-63. doi: 10.1016/j.jmr.2011.06.009. Epub 2011 Jul 12.
Chemical shift imaging (CSI) without water suppression was used to examine tissue-specific resonance frequencies of water and metabolites within the human brain. The aim was to verify if there are any regional differences in those frequencies and to determine the influence of chemical shift displacement in slice-selection direction. Unsuppressed spectra were acquired at 3T from nine subjects. Resonance frequencies of water and after water signal removal of total choline, total creatine and NAA were estimated. Furthermore, frequency distances between the water and those resonances were calculated. Results were corrected for chemical shift displacement. Frequency distances between water and metabolites were consistent and greater for GM than for WM. The highest value of WM to GM difference (14ppb) was observed for water to NAA frequency distance. This study demonstrates that there are tissue-specific differences between frequency distances of water and metabolites. Moreover, the influence of chemical shift displacement in slice-selection direction is showed to be negligible.
化学位移成像是一种无需水抑制的技术，用于检测人脑内水和代谢物的组织特异性共振频率。本研究旨在验证这些频率是否存在区域差异，并确定在层面选择方向上化学位移的影响。在 3T 下，从 9 名受试者中获得了未受抑制的光谱。估计了水的共振频率以及水信号去除后总胆碱、总肌酸和 NAA 的共振频率。此外，还计算了水与这些共振之间的频率差。结果针对化学位移进行了校正。水和代谢物之间的频率差在 GM 中比在 WM 中更一致且更大。WM 与 GM 之间的频率差最大（14ppb），观察到的是水与 NAA 之间的频率差。本研究表明，水和代谢物之间的频率差存在组织特异性差异。此外，还表明层面选择方向上化学位移的影响可以忽略不计。
