Resolution improvements in in vivo 1H NMR spectra with increased magnetic field strength
Resolution improvements in in vivo 1H NMR spectra with increased magnetic field strength
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DOI：
10.1006/jmre.1998.1542
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发表时间：
1998-11-01
影响因子：
2.2
通讯作者：
Ugurbil, K
中科院分区：
文献类型：
--
作者：
Gruetter, R;Weisdorf, SA;Ugurbil, K
使用高度同源定位技术和类似的匀场方法，在1.5和4 T的人脑中以及在9.4 T的犬和大鼠脑中进行了脑代谢物的测量。在大鼠大脑中，通过使用完全绝热FASTMAP序列对所有一阶和二阶匀场线圈进行匀场来实现分辨率的提高。光谱显示，随着场强的增加，所有代谢物共振的光谱分辨率明显提高。在肝性脑病患者中，与1.5 T相比，在4 T下清楚地观察到脑谷氨酰胺含量的变化。在9.4 T下，2.46 ppm的谷氨酰胺H4与2.37 ppm的谷氨酸H4完全分离，2.30 ppm的γ-氨基丁酸和2.05 ppm的N-乙酰基-乙酰基-谷氨酸的潜在共振也是如此。单态线宽被发现是低至6 Hz（0.015 ppm），在9.4 T，表明一个显着减少ppm线宽与场强。此外，肌酸的亚甲基峰与磷酸肌酸部分分离，表明灰质中的关系接近1：1。我们的结论是，增加磁场强度增加光谱分辨率也为H-1 NMR，这可能会导致超过线性灵敏度增益。(C)北京：科学出版社.
The measurement of cerebral metabolites using highly homologous localization techniques and similar shimming methods was performed in the human brain at 1.5 and 4 T as well as in the dog and rat brain at 9.4 T. In rat brain, improved resolution was achieved by shimming all first- and second-order shim coils using a fully adiabatic FASTMAP sequence. The spectra showed a clear improvement in spectral resolution for all metabolite resonances with increased field strength. Changes in cerebral glutamine content were clearly observed at 4 T compared to 1.5 T in patients with hepatic encephalopathy. At 9.4 T, glutamine H4 at 2.46 ppm was fully resolved from glutamate H4 at 2.37 ppm, as was the potential resonance from gamma-amino-butyric acid at 2.30 ppm and N-acetyl-aspartyl-glutamate at 2.05 ppm. Singlet linewidths were found to be as low as 6 Hz (0.015 ppm) at 9.4 T, indicating a substantial decrease in ppm linewidth with field strength. Furthermore, the methylene peak of creatine was partially resolved from phosphocreatine, indicating a close to 1:1 relationship in gray matter. We conclude that increasing the magnetic field strength increases spectral resolution also for H-1 NMR, which can lead to more than linear sensitivity gains. (C) 1998 Academic Press.