Proton T2 Measurement and Quantitation of Coupled-Spin Metabolites in Human Brain by PRESS at 3T in Vivo

Changho Choi¹, Aditya Patel¹, Deborah Douglas¹, Ivan Dimitrov^1,2

Proton T2 measurement and quantification of brain coupled-spin metabolites in the human brain, at 3T, is reported. Four pairs of PRESS (point resolved spectroscopy) subecho times, which were obtained with numerical analyses of the sequence for optimal separation between glutamate (Glu) and glutamine (Gln), were used for T2 measurement. Single-voxel measurements were carried out on the occipital cortex of five healthy volunteers. Spectra were analyzed with LCModel fitting. From monoexponential fitting of the LCModel estimates at the selected TEs, apparent T2s of Glu, Gln, and myo-inositol (mIns) were measured to be 160 - 170 ms. Further, the signal strengths measured with TR = 8 s were extrapolated to zero TE using the estimated T2 values. The concentration ratio with respect to creatine was estimated to be 8.21.3, 4.60.6, 9.50.8, and 1.10.1 (meanSD, N = 5) for Glu, mIns, NAA, and GPC+PC, respectively.