Abstract
Brown adipose tissue (BAT) is identified in mammals as an adaptive thermogenic organ for modulation of energy expenditure and heat generation. Human BAT may be primarily composed of brown-in-white (BRITE) adipocytes and stimulation of BRITE may serve as a potential target for obesity interventions. Current imaging studies of BAT detection and characterization have been mainly limited to PET/CT. MRI is an emerging application for BAT characterization in healthy children. To exploit Dixon and diffusion-weighted MRI methods to characterize cervical-supraclavicular BAT/BRITE properties in normal-weight and obese children while accounting for pubertal status. Twenty-eight healthy children (9-15 years old) with a normal or obese body mass index participated. MRI exams were performed to characterize supraclavicular adipose tissues by measuring tissue fat percentage, T2*, tissue water mobility, and microvasculature properties. We used multivariate linear regression models to compare tissue properties between normal-weight and obese groups while accounting for pubertal status. MRI measurements of BAT/BRITE tissues in obese children showed higher fat percentage (P < 0.0001), higher t2* (p >< 0.0001), and lower diffusion coefficient (p =" 0.015)" compared with normal-weight children. pubertal status was a significant covariate for the t2* measurement, with higher t2* (p =" 0.0087)" in pubertal children compared to prepubertal children. perfusion measurements varied by pubertal status. compared to normal-weight children, obese prepubertal children had lower perfusion fraction (p =" 0.003)" and pseudo-perfusion coefficient (p =" 0.048);" however, obese pubertal children had higher perfusion fraction (p =" 0.02)" and pseudo-perfusion coefficient (p =" 0.028)." this study utilized chemical-shift dixon mri and diffusion-weighted mri methods to characterize supraclavicular bat brite tissue properties. the multi-parametric evaluation revealed evidence of morphological differences in brown adipose tissues between obese and normal-weight children.>
