LOCALIZED P-31 NMR-SPECTROSCOPY OF THE ADULT HUMAN BRAIN INVIVO USING STIMULATED-ECHO (STEAM) SEQUENCES

Phosphorus NMR spectroscopy of the brain of healthy volunteers (20-25 years) has been performed with use of the stimulated-echo (STEAM) localization technique. Investigations were carried out on a 2.0 T whole-body MRI/MRS system (Siemens Magnetom). Phosphorus spectra with echo times of TE ≥ 3 ms were typically obtained in measuring times of about 10 min from a 125 ml volume-of-interest localized in the occipital part of the brain. The spectral resolution was optimized by localized shimming on the water proton signal (5-7 Hz) using the same sequence. Relaxation data were evaluated from spectra acquired under experimental conditions matched to the relaxation times of the individual metabolite resonances. Echo times ranged from 5 to 115 ms for T2 determinations. For t1 determinations repetition times were varied from 500 to 9000 ms. Broadband proton decoupling was achieved by means of a WALTZ-8 composite pulse sequence applied for the initial 68 ms of the 256 ms phosphorus acquisition period. © 1990.