Brown adipose tissue and its relationship to bone structure in pediatric patients

Abstract

Context: Emerging evidence suggests a possible link between brown adipose tissue (BAT) and bone metabolism.

Objective: The objective of this study was to examine the relationships between BAT and bone cross-sectional dimensions in children and adolescents.

Design: This was a cross-sectional study.

Setting: The study was conducted at a pediatric referral center.

Patients: Patients included 40 children and teenagers (21 males and 19 females) successfully treated for pediatric malignancies.

Interventions: There were no interventions.

Main outcome measures: The volume of BAT was determined by fluorodeoxyglucose-positron emission tomography/computed tomography. Measures of the cross-sectional area and cortical bone area and measures of thigh musculature and sc fat were determined at the midshaft of the femur.

Results: Regardless of sex, there were significant correlations seen between BAT volume and the cross-sectional dimensions of the bone (r values between 0.68 and 0.77; all P ≤ 0 .001). Multiple regression analyses indicated that the volume of BAT predicted femoral cross-sectional area and cortical bone area, even after accounting for height, weight, and gender. The addition of muscle as an independent variable increased the predictive power of the model but significantly decreased the contribution of BAT.

Conclusions: 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.

Fig. 1.

Coregistered CT and PET images from the same subject at two different levels. Arrows point to symmetrical uptake of radiotracers by BAT in foci with high SUV (>1.5), which correspond to negative Hounsfield unit voxels (−20 to −200) in the associated CT images. The third row illustrates the corresponding segmented adipose tissue masks from Matlab. White voxels denote mostly sc WAT, whereas interscapular BAT is gray.

Fig. 2.

Coronal PET scans of the neck and upper chest of girls with high (top panel) and low (bottom panel) BAT volumes. Corresponding CT images of the midshaft of the femurs of the same subjects show larger cross-sectional femoral dimensions (top panel) in the subject with greater BAT volume.

Fig. 3.

Correlation between femoral CBA and BAT volume (A) and femoral CSA and BAT volume (B).