13C MRS of occipital and frontal lobes at 3 T using a volume coil for stochastic proton decoupling

Previously, we devised a novel strategy for in vivo C-13 MRS using (2-C-13)glucose infusion and low-power proton decoupling, and proposed that this strategy could be used to acquire C-13 MR spectra from the frontal lobe of the human brain. Here, we demonstrate, for the first time, in vivo C-13 MRS of human frontal lobe acquired at 3 T. Because the primary metabolites of [2-C-13]glucose can be decoupled using very-low-radiofrequency power, we used a volume coil for proton decoupling in this study. The homogeneous B-1 field of the volume coil was found to significantly enhance the decoupling efficiency of the stochastic decoupling sequence. Detailed specific absorption rates inside the human head were analyzed using the finite difference time domain method to ensure experimental safety. In vivo C-13 spectra from the occipital and frontal lobes of the human brain were obtained. At a decoupling power of 30W (time-averaged power, 2.45W), the spectra from the occipital lobe showed well-resolved spectral resolution and excellent signal-to-noise ratio. Although frontal lobe C-13 spectra were affected by local B-0 field inhomogeneity, we demonstrated that the spectral quality could be improved using post-acquisition data processing. In particular, we showed that the frontal lobe glutamine C5 at 178.5 ppm and aspartate C4 at 178.3 ppm could be spectrally resolved with effective proton decoupling and B-0 field correction. Because of its large spatial coverage, volume coil decoupling provides the potential to acquire C-13 MRS from more than one brain region simultaneously. Copyright (c) 2010 John Wiley & Sons, Ltd.