Changho Choi1, Deborah Douglas1,
Aditya Patel1,
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).