3D RINEPT {1H}-31P CSI: a feasible approach for the study of membrane turnover in the human brain.

A fast, full 3D elliptical k-space encoding phosphorous-31 ((31)P) chemical shift imaging sequence, incorporating heteronuclear polarization transfer editing (RINEPT), was established. RINEPT literally requires simultaneous pulses at the frequencies of both the sensitive and the insensitive nuclei, but only a few MR imaging systems feature a second independent transmit channel. In this study, possible signal degradation of a sequential sequence design on systems featuring a single transmit channel was investigated with spin density matrix calculations and phantom measurements. In addition, metabolite signal intensities were determined in vivo as a function of echo and repetition times. The results enable optimization of the signal-to-noise ratio of one or more metabolites of interest. The results convincingly show that the optimized RINEPT sequence is useful in clinical routine (31)PMRS protocols and provides spectra of excellent quality for the study of cell membrane phospholipid turnover in the human brain even at a low field strength of 1.5T. The 3D sequence design allows covering the whole brain in a single measurement, while scan times are compliant with clinical routine protocols. (c) 2008 Wiley-Liss, Inc.