Semiselective POCE NMR spectroscopy

A new scheme is proposed to edit separately glutamate C₃ and C₄ resonances of ¹H bound to ¹³C, in order to resolve these two signals which overlap at intermediate magnetic fields (1.5 T-3 T), commonly available for human brain studies. The two edited spectra are obtained by combining the individual acquisitions from a four-scan measurement in two different ways. The four acquisitions correspond to the two steps of the classical POCE scheme combined with another two-scan module, where the relative phases of the C₃ and C₄ ¹H resonances are manipulated using zero quantum and double quantum coherence pathways. This new technique exhibits the same sensitivity as POCE and allows the ¹³C labeling of C₃ and C₄ glutamate from [1-¹³C]glucose to be monitored separately in the rat brain at 3 T. (C) 2000 Wiley-Liss, Inc.