Detection of glutathione in the human brain in vivo by means of double quantum coherence filtering.

The feasibility of selective in vivo detection of glutathione (L-gamma-glutamyl-L-cysteinyl-glycine, GSH) in the human brain by means of (1)H magnetic resonance spectroscopy (MRS) at 1.5 T is demonstrated. A double quantum coherence (DQC) filtering sequence was used in combination with PRESS volume selection. The strongly coupled cysteinyl CH(2) compound of GSH was found to be the most suitable target for spectral editing. Analytical calculations employing a product operator description of the cysteinyl ABX three-spin system were made in order to optimize the inherent yield of the sequence. A pulse phase calibration procedure, which precedes the spectrum acquisition, secures maximal signal yield independently of the spatial localization of the volume of interest and thus comparability between individual examinations. In vitro tests show that the DQC filtering method provides good discrimination between the GSH signal at 2.9 ppm and the interfering resonances of creatine, gamma-aminobutyric acid (GABA) and aspartate. In measurements in the frontal lobe of 12 healthy volunteers a mean ratio of GSH signal to tissue water signal of 5.7 +/- 2.3 x 10(-5) was found, corresponding to a mean GSH tissue concentration of 2-5 mmol/L. The proposed technique allows for the detection of a biologically highly relevant metabolite at moderate field strength. Magn Reson Med 42:283-289, 1999. Copyright 1999 Wiley-Liss, Inc.