PROTON-DECOUPLED P-31 CHEMICAL-SHIFT IMAGING OF THE HUMAN BRAIN IN NORMAL VOLUNTEERS

Proton-decoupled, P-31 three-dimensional (3-D) chemical shift imaging (CSI) spectra have been acquired from the entire human brain using a new dual tuned resonator. The resonator operates in quadrature mode to provide improved sensitivity, excellent B1 homogeneity, and reduced power deposition at both frequencies. Proton-decoupled and fully NOE enhanced P-31 SpeCtra were acquired from normal volunteers using Waltz-4 proton decoupling with continuous wave bi-level excitation applied through a second radio frequency channel. Well resolved peaks in the phosphomonoester (PME) and phosphodiester regions were obtained from nonlocalized FIDs and spectra localized with 3-D CSI without processing for resolution enhancement. pH measurements made over large regions of the brain using the P(i) resonance show no significant variations (6.9+/-0.02) for a single individual. The improved spectral resolution and sensitivity of the PME resonances results in more well defined metabolite images of the PME peak region.