Purpose To compare fat-signal fractions (FFs) and T2* values between brown (BAT) and white (WAT) adipose tissue located within the supraclavicular fossa and subcutaneous depots, respectively. Materials and Methods Twelve infants and 39 children were studied. Children were divided into lean and overweight/obese sub-groups. Chemical-shift-encoded water-fat MRI was used to quantify FFs and T2* metrics in the supraclavicular and adjacent subcutaneous adipose tissue depots. Linear regression and t-tests were performed. Results Infants had lower supraclavicular FFs than children (p<0.01) but T2* values were similar (p=0.5). Lean children exhibited lower supraclavicular FFs and T2* values than overweight children (p<0.01). In each individual infant and child, supraclavicular FFs were consistently lower than adjacent subcutaneous FFs. Supraclavicular T2* values were consistently lower than subcutaneous T2* values in children, but not in infants. FFs in both depots were positively correlated with age and weight in infants (p<0.01). In children, they were correlated with weight and BMI (p<0.01), but not age. Correlations between T2* and anthropometric variables existed in children (p<0.01), but were absent in infants. Conclusion Cross-sectional comparisons suggest variations in FF and T2* values in the supraclavicular and subcutaneous depots of infants and children, which are potentially indicative of physiological differences in adipose tissue fat content, amount, and metabolic activity.

The volume of BAT is positively associated with the amount of bone and the cross-sectional size of the femur in children and adolescents. This relation between BAT and bone structure could, at least in part, be mediated by muscle.

Purpose-To compare fat-signal fractions (FFs) and T 2 * values between brown (BAT) and white (WAT) adipose tissue located within the supraclavicular fossa and subcutaneous depots, respectively.Materials and Methods-Twelve infants and 39 children were studied. Children were divided into lean and overweight/obese sub-groups. Chemical-shift-encoded water-fat MRI was used to quantify FFs and T 2 * metrics in the supraclavicular and adjacent subcutaneous adipose tissue depots. Linear regression and t-tests were performed.Results-Infants had lower supraclavicular FFs than children (p<0.01) but T 2 * values were similar (p=0.5). Lean children exhibited lower supraclavicular FFs and T 2 * values than overweight children (p<0.01). In each individual infant and child, supraclavicular FFs were consistently lower than adjacent subcutaneous FFs. Supraclavicular T 2 * values were consistently lower than subcutaneous T 2 * values in children, but not in infants. FFs in both depots were positively correlated with age and weight in infants (p<0.01). In children, they were correlated with weight and BMI (p<0.01), but not age. Correlations between T 2 * and anthropometric variables existed in children (p<0.01), but were absent in infants.Conclusion-Cross-sectional comparisons suggest variations in FF and T 2 * values in the supraclavicular and subcutaneous depots of infants and children, which are potentially indicative of physiological differences in adipose tissue fat content, amount, and metabolic activity.

4.