Subcutaneous and visceral fat assessment by DXA and MRI in older adults and children

Objective: Given the importance of body fat distribution in chronic disease development, feasible methods to assess body fat are essential. This study compared dual-energy x-ray absorptiometry (DXA) in measuring visceral and subcutaneous adipose tissue (VAT and SAT) with magnetic resonance imaging (MRI).

Methods: VAT and SAT were assessed using similar DXA and MRI protocols among 1,795 elderly participants of the Adiposity Phenotype Study (APS) and 309 children/adolescents in Shape Up! Kids (SKids). Spearman correlations, Bland-Altman plots, and coefficients of determination (R² ) assessed agreement between DXA and MRI measures.

Results: DXA overestimated SAT values in APS (315 vs. 229 cm² ) and SKids (212 vs. 161 cm² ), whereas DXA underestimated VAT measures (141 vs. 167 cm² ) in adults only. The correlations between DXA and MRI values were stronger for SAT than VAT (APS: r = 0.92 vs. 0.88; SKids: 0.90 vs. 0.74). Bland-Altman plots confirmed better agreement for SAT than VAT despite differences by sex, ethnicity, and weight status with respective R² values for SAT and VAT of 0.88 and 0.84 (APS) and 0.81 and 0.69 (SKids).

Conclusion: These findings indicate that SAT by DXA reflects MRI measures in children and older adults, whereas agreement for VAT is weaker for individuals with low VAT levels.