Value of MRI and MRS fat measurements to complement conventional screening methods for childhood obesity.

ABSTRACT

PURPOSE: To evaluate a protocol combining abdominal fat-water magnetic resonance imaging (MRI) and liver single voxel magnetic resonance spectroscopy (MRS) for studies of childhood obesity. MATERIALS AND METHODS: Six obese male children and five age-matched normal-weight controls underwent abdominal fat-water Dixon MRI based on a gradient echo sequence with multiple echo times and single voxel liver MRS at a field strength of 3T. The MRI/MRS data were compared with data previously acquired from an obese adult cohort and with anthropometric and blood parameters that are typically acquired for screening in childhood obesity. RESULTS: There was a very strong correlation (r = 0.96) between the body mass index standard deviation score (BMI-SDS) and the subcutaneous fat volume fraction in the examined children, but only a moderate correlation (r = 0.62) between the BMI-SDS index and the intraabdominal fat volume fraction, which is much lower in the obese children (5.3 ± 1.1%) than in the obese adult cohort (19.4 ± 2.9%). Furthermore, a significant difference between the two child cohorts was observed in the intrahepatic lipid (IHL) content as obtained with MRS (P = 0.017). However, even the obese child cohort shows an IHL content that is 1-2 orders of magnitude lower (1.0 ± 0.5%) than in the obese adult cohort (17.0 ± 8.7%). CONCLUSION: The proposed method was successfully applied in children and may complement traditional clinical screening methods for childhood obesity such as anthropometry and laboratory tests to better characterize the obesity-associated metabolic risk.