Changho Choi1, Deborah Douglas1,
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States; 2Internal Medicine and Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States; 3Philips Medical Systems, Cleveland, OH, United States
Glycine (Gly) in human brain was measured using an optimized PRESS (point-resolved spectroscopy) sequence at 3T. Echo time dependence of the coupled resonances of myo-inositol (mIns) was investigated, with numerical analyses, for TE1 and TE2 between 20 and 200 ms. The numerical simulation indicated that a pair of subecho times, (TE1, TE2) = (60, 100) ms, suppresses the mIns resonances at 3.5 3.6 ppm, providing an effective tool for measuring Gly and mIns simultaneously. In vivo tests of the method were carried out on six subjects. With LCModel fitting, [Gly]/[Cr] and [mIns]/[Cr] were estimated to be 0.080.01 and 0.700.07 (meanSD, N = 3) for the occipital lobe, and 0.070.01 and 0.810.21 (N = 3) for the parietal lobe, respectively. The Cramr-Rao lower bounds (CRLB) of Gly were 91% (N = 6).