Abstract
Abstract
Purpose
With growing interest in pediatric MRS to understand the neurochemistry of brain development, it is essential to establish pediatric-specific metabolite T
1
and T
2
relaxation times for reliable quantification of metabolites. Furthermore, characterization of age-related changes in relaxation times may provide insight into developmental differences in tissue microstructure and cellular composition. Therefore, the goals of this study were two-fold: (1) to estimate metabolite T
1
and T
2
relaxation times in a pediatric cohort; and (2) to assess linear relationships between age and relaxation times.
Methods
TI- and TE-series data were acquired from the bilateral thalamus in 20 and 25 participants aged between 0 and 7 years, respectively. Data were processed and modelled in Osprey 2.5.0. Metabolite T
1
and T
2
relaxation times of total N-acetylaspartate at 2.0 ppm (tNAA
2.0
), total creatine at 3.0 ppm (tCr
3.0
), total creatine at 3.9 ppm (tCr
3.9
), total choline (tCho), myo-inositol (mI) and the combined glutamate and glutamine (Glx) were estimated by fitting the modelled signal amplitudes to TI-series inversion recovery signal and TE-series exponential decay equations, respectively. Linear relationships with age were tested for metabolite T
1
and T
2
relaxation times using Spearman correlations.
Results
tNAA
2.0
and Glx showed significant changes in T
1
with age. tNAA
2.0
, tCr
3.0
, tCho and mI showed significant decrease in T
2
with age.
Conclusion
Several metabolites showed significant changes in relaxation times with age in the thalamus region. Therefore, use of age-specific relaxation correction for pediatric studies using the linear equations provided is encouraged for reliable quantification of metabolites.