Surface-coil polarization transfer for monitoring tissue metabolism in vivo

Polarization transfer methods can substantially enhance NMR signals from nu clei of low gamma, which are J-coupled to nuclei of high gamma, but to date have had limited application for in vivo P-31 MRS studies. They require bo th accurate flip angles and good localization in order to achieve their pot ential. Described here is an implementation of the insensitive nuclei enhan ced by polarization transfer (INEPT) polarization transfer method using seg mented adiabatic BIR4 RF pulses. Localization uses ISIS, applied to the cou pled H-1 spins. Detailed analysis is performed to evaluate the specific abs orption rate power deposition when using surface coils. Polarization transf er, localization capability, and use with surface coils are demonstrated us ing suitable test objects. Finally, in vivo data are presented from the liv er of a normal volunteer in which the signals from the phosphodiester peaks are substantially enhanced. (C) 2000 Wiley-Liss, Inc.