Metabolic changes in early childhood using LCModel with corrected water scaling method

Abstract

To examine metabolic changes of the brain in early infancy measured by the LCModel with the water scaling method (LCModel-WS), and to determine whether the unsuppressed water signal (UWS) on the MR console and the area of the unsuppressed water peak (AUW) in the LCModel can be used to correct metabolite concentrations. MR spectroscopy was performed on a 1.5 Tesla MR scanner. To determine whether UWS and AUW increases linearly with PD and exp(-TE/T2), these values were measured using three phantoms with different PD and T2 values. UWS and AUW were also measured (PRESS, TR = 5000 ms, TE = 30 ms, VOI = 4.5 mL) in 57 pediatric controls (aged 2 weeks to 15 years). Phantom studies revealed UWS and AUW increases linearly with PD and exp(-TE/T2). UWS and AUW were high in controls younger than 2 years of age, but gradually decreased to become almost constant after 4 years (UWS = 504 × 10(3) , AUW = 2.05 × 10(7)). AUW was linearly proportional to UWS in controls. These indicated that metabolite concentrations should be multiplied by the ratio of UWS/504 × 10(3) or AUW/2.05 × 10(7). Age dependent metabolite concentrations corrected by the ratio were obtained. Both UWS and AUW can be used to correct metabolite concentrations; these corrections can significantly improve quantification of metabolites' concentration in early childhood.