Table 1.
Heteronuclear MRS methods for studying the glutamate–glutamine cycle using infusion of 13C-labeled substrates.
| 13C{1H} | Detect aliphatic carbons such as glutamate C4 and glutamine C4; use either carbon excitation or proton excitation and subsequent proton-to-carbon polarization transfer; need high power coherent proton decoupling (de Graaf et al., 2011) |
| Detect carboxylic carbons such as glutamate C5 and glutamine C5; use carbon excitation; can use low power stochastic proton decoupling (Li et al., 2009) | |
| 1H{13C} | Detect aliphatic protons such as glutamate H4 and glutamine H4; use proton excitation and proton detection; need high power coherent carbon decoupling (de Graaf et al., 2011) |