Broadband proton decoupling for in vivo brain spectroscopy in humans

A new decoupling sequence, PEAR, is described for broadband heteronuclear decoupling in vivo in humans at 1.5T. The sequence uses non-adiabatic, frequency- and amplitude-modulated inversion pulses designed to minimize decoupling sidebands at low applied gammaB(2) RF field levels and to cover only the narrow range of resonance offsets encountered in practice. The offset dependence of the decoupling efficiency of PEAR is demonstrated and compared to the conventional WALTZ-4 sequence. At the same average power levels, PEAR had slightly reduced bandwidth but significantly less intense decoupling sidebands. Applications of PEAR are shown in vivo in the human brain both for P-31 and natural abundance C-13 spectroscopy using volume decoupling coils. The PEAR sequence allows whole brain {H-1}-C-13 decoupling to be performed at 1.5T with a standard head coil within FDA guidelines for RF power deposition. Magn Reson Med 45:226-232, 2001. (C) 2001 Wiley-Liss, Inc.