PROTON SPECTROSCOPY OF HUMAN BRAIN WITH VERY SHORT ECHO TIME USING HIGH-GRADIENT AMPLITUDES

In localized proton magnetic resonance spectroscopy very short echo ti mes (TE) are achieved to diminish signal loss due to T-2 relaxation an d to avoid phase distortions due to J-coupling, A sequence for single volume spectroscopy in human brain is described with a TE as low as 5 ms, Examinations were performed on a 1.5 T whole-body imager with acti vely shielded gradients, A self-designed stimulated echo acquisition m ode (STEAM I) sequence with very high amplitude spoiling gradients of 24 mT/m was used to take advantage of the whole potential of the gradi ent system, Optimization of TE was carried out by controlling spectral quality and localization in both phantom and volunteer measurements. Proton spectra of human brain were acquired in 21 healthy volunteers, Spectra of occipital white matter, parieto-occipital grey/white matter , and cerebellum revealed none or only small eddy current distortions at a TE of 5 ms, The volume of interest was 8-12 mi, repetition time w as 1.5 s, and mixing time was 5 ms, Peak ratios of major metabolites r eferring to creatine were estimated and the relative standard deviatio ns were calculated to determine interindividual reproducibility. The r elative standard deviation of myo-inositol ranged from 6% to 11% withi n these brain regions whereas for glutamine and glutamate 78 to 16% we re found. (C) 1998 Elsevier Science Inc.