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.