Chen Hao, De Feyter Henk M, Brown Peter B, Rothman Douglas L, Cai Shuhui, de Graaf Robin A
Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale University, School of Medicine, New Haven, CT, USA; Department of Electronic Science, Xiamen University, Xiamen, Fujian, China.
Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale University, School of Medicine, New Haven, CT, USA.
J Magn Reson. 2017 Oct;283:33-44. doi: 10.1016/j.jmr.2017.08.004. Epub 2017 Aug 12.
A wide range of direct C and indirect H-[C] MR detection methods exist to probe dynamic metabolic pathways in the human brain. Choosing an optimal detection method is difficult as sequence-specific features regarding spatial localization, broadband decoupling, spectral resolution, power requirements and sensitivity complicate a straightforward comparison. Here we combine density matrix simulations with experimentally determined values for intrinsic H and C sensitivity, T and T relaxation and transmit efficiency to allow selection of an optimal C MR detection method for a given application and magnetic field. The indirect proton-observed, carbon-edited (POCE) detection method provides the highest accuracy at reasonable RF power deposition both at 4T and 7T. The various polarization transfer methods all have comparable performances, but may become infeasible at 7T due to the high RF power deposition. 2D MR methods have limited value for the metabolites considered (primarily glutamate, glutamine and γ-amino butyric acid (GABA)), but may prove valuable when additional information can be extracted, such as isotopomers or lipid composition. While providing the lowest accuracy, the detection of non-protonated carbons is the simplest to implement with the lowest RF power deposition. The magnetic field homogeneity is one of the most important parameters affecting the detection accuracy for all metabolites and all acquisition methods.
存在多种直接碳（C）和间接氢-碳（H-[C]）磁共振检测方法来探测人类大脑中的动态代谢途径。由于在空间定位、宽带去耦、光谱分辨率、功率要求和灵敏度等方面的序列特异性特征使得直接比较变得复杂，因此选择最佳检测方法很困难。在这里，我们将密度矩阵模拟与通过实验确定的固有氢和碳灵敏度、T1和T2弛豫以及发射效率值相结合，以便为给定的应用和磁场选择最佳的碳磁共振检测方法。间接质子观测碳编辑（POCE）检测方法在4T和7T的合理射频功率沉积下都能提供最高的准确性。各种极化转移方法都具有相当的性能，但在7T时由于高射频功率沉积可能变得不可行。二维磁共振方法对于所考虑的代谢物（主要是谷氨酸、谷氨酰胺和γ-氨基丁酸（GABA））价值有限，但当可以提取额外信息（如同位异构体或脂质组成）时可能证明是有价值的。虽然准确性最低，但非质子化碳的检测是最容易实现的，射频功率沉积也最低。磁场均匀性是影响所有代谢物和所有采集方法检测准确性的最重要参数之一。
