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Abstract #1399

GABA Fitting for MEGA-PRESS Sequences with Different Selective Inversion Frequencies

Zaiyang Long1,2, James Brown Murdoch3, Jun Xu1,2, Ulrike Dydak1,2

1School of Health Sciences, Purdue University, West Lafayette, IN, United States; 2Department of Radiology & Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, United States; 3Toshiba Medical Research Institute USA, Mayfield Village, OH, United States

In this study, we compare three LCModel fitting techniques for the original MEGA-PRESS sequence and a modified MM-symmetric version which has editing pulses alternating between 1.9 ppm and 1.5 ppm. Fitting technique A yields the highest GABA concentrations with small CRLB values, but the concentrations are probably overestimated. Technique B with an added MM30 peak yields the lowest GABA concentrations with largest CRLB. Fitting technique C with a soft constraint on MM30 seems to work best for the original MEGA-PRESS sequence and technique A for the MM-symmetric version. GABA levels may deviate considerably if an inappropriate fitting approach is chosen.