CORRECTION OF PHASE EFFECTS PRODUCED BY EDDY CURRENTS IN SOLVENT SUPPRESSED H-1-CSI

Accurate phasing of MRS spectra is often difficult unless time varying phase effects produced by gradient-induced eddy currents that persist during data acquisition are eliminated. This effect is particularly p roblematic in H-1-CSI spectra where frequency shifts produced by stati c field inhomogeneity and phase shifts produced by eddy currents combi ne. In this paper we present a method that corrects both shifts and el iminates manual phasing of individual CSI spectra typically required t o recover a pure absorption line shape. The method uses a time domain phase correction derived from the ambient water signal acquired under identical conditions (i.e., acquisition parameters, gradient sequence) as the solvent-suppressed CSI data. Results from CSI experiments on p hantoms and in vivo solvent suppressed H-1-CSI spectra from normal hum an brain are presented demonstrating the capabilities of the technique .