Dual-energy X-ray absorptiometry prediction of adipose tissue depots in children and adolescents

Abstract

Background: The measurement of adipose tissue (AT) depots in vivo requires expensive imaging methods not accessible to most clinicians and researchers. The study aim was to derive mathematical models to predict total AT (TAT) and subdepots from total body fat derived from a dual-energy X-ray absorptiometry (DXA) scan.

Methods: Models were developed to predict magnetic resonance imaging-derived TAT and subdepots subcutaneous AT, visceral AT, and intermuscular AT from DXA total body fat (Fat(DXA)) using cross-sectional data (time 0 (T0)) and validated results using 1 (T1) and 2 (T2) y follow-up data. Subjects were 176 multiethnic healthy children ages 5-17 y at T0. Twenty-two were measured at T1 and T2. TAT was compared with Fat(DXA).

Results: At T0, TAT was greater than Fat(DXA) (12.5 ± 8.4 vs.12.0 ± 9.4 kg; P < 0.0001), with a quadratic relationship between TAT and Fat(DXA) that varied by sex. Predicted mean TATs were not different from measured TATs: T1: (9.84 ± 4.45 kg vs. 9.50 ± 4.37 kg; P = 0.11); T2: (12.94 ± 6.75 kg vs. 12.89 ± 7.09 kg; P = 0.76). The quadratic relationship was not influenced by race or age.

Conclusion: In general, the prediction equations for TAT and subdepots were consistent with the measured values using T1 and T2 data.

Figure 1

Relations (quadratic) between fat by dual-energy X-ray absorptiometry (DXA) and total dipose tissue (TAT) by magnetic resonance imaging in males (A) and females (B): Males: TAT (kg) = 2.64+0.79*fat(kg)+0.002*fat(kg)² (R²_PRESS=0.99, p<0.0001; standard estimation error_PRESS = 1.01 kg, n=103). Females: TAT (kg) = 2.19+0.78*fat(kg)+0.003*fat(kg)² (R²_PRESS=0.99, p<0.0001; standard estimation error_PRESS = 1.01 kg, n=73).