Selective resonance suppression 1H‐[13C] NMR spectroscopy with asymmetric adiabatic RF pulses

Despite obvious improvements in spectral resolution at high magnetic field, the detection of ¹³C labeling by ¹H‐[¹³C] NMR spectroscopy remains hampered by spectral overlap, such as in the spectral region of ¹H resonances bound to C3 of glutamate (Glu) and glutamine (Gln), and C6 of N‐acetylaspartate (NAA). The aim of this study was to develop, implement, and apply a novel ¹H‐[¹³C] NMR spectroscopic editing scheme, dubbed “selective Resonance suppression by Adiabatic Carbon Editing and Decoupling single‐voxel STimulated Echo Acquisition Mode” (RACED‐STEAM). The sequence is based on the application of two asymmetric narrow‐transition‐band adiabatic RF inversion pulses at the resonance frequency of the ¹³C coupled to the protons that need to be suppressed during the mixing time (TM) period, alternating the inversion band downfield and upfield from the ¹³C resonance on odd and even scans, respectively, thus suppressing the detection of ¹H resonances bound to ¹³C within the transition band of the inversion pulse. The results demonstrate the efficient suppression of ¹H resonances bound to C3 of Glu and Gln, and C4 of Glu, which allows the ¹H resonances bound to C6 of NAA and C4 of Gln to be revealed. The measured time course of the resolved labeling into NAA C6 with the new scheme was consistent with the slow turnover of NAA. Magn Reson Med 61:260–266, 2009. © 2009 Wiley‐Liss, Inc.