MR spectroscopy of liver in overweight children and adolescents: Investigation of 1H T2 relaxation times at 3 T

Objective: The objective was to investigate T2 relaxation values and to optimize hepatic fat quantification using proton MR spectroscopy (1H MRS) at 3 T in overweight and obese children and adolescents. Subjects: The study included 123 consecutive children and adolescents with a body mass index above the 97th percentile according to age and sex. 1H MR spectroscopy was performed at 3.0 T using point resolved spectroscopy sequence with series TE. T2 relaxation values and hepatic fat content corrected for the T2 relaxation effects were calculated. Results: T2 values for water ranged from 22 ms to 42 ms (mean value 28 ms) and T2 values for fat ranged from 36 ms to 99 ms (mean value 64 ms). Poor correlation was observed: (1) between T2 relaxation times of fat and T2 relaxation times of water (correlation coefficient r = 0.038, P = 0.79); (2) between T2 relaxation times of fat and fat content (r = 0.057, P = 0.69); (3) between T2 relaxation times of water and fat content (r = 0.160, P = 0.26). Correlation between fat peak content and the T2 corrected fat content decreased with increasing echo time TE: r = 0.97 for TE = 45, r = 0.93 for TE = 75, r = 0.89 for TE = 105, P < 0.0001. Conclusion: 1H MRS at 3 T is an effective technique for measuring hepatic fat content in overweight and obese children and adolescents. It is necessary to measure T2 relaxation values and to correct the spectra for the T2 relaxation effects in order to obtain an accurate estimate of the hepatic fat content.