Body fat estimation in children by magnetic resonance imaging, bioelectrical impedance, skinfold and body mass index: a pilot study.

Abstract

The aim of this study was to identify the clinical method to estimate body fat which gave best correlation of total body fat and percentage body fat as measured on MRI. Magnetic resonance imaging (MRI) was used to estimate the total body fat volume and percentage body fat and this was compared with assessment by bioelectrical impedance (BEI), skinfold thickness and body mass index (BMI) in 8- to 12-year-old children. Total body fat measured on magnetic resonance imaging (TBF-MRI) significantly correlated with body mass index, triceps and subscapular skinfolds, and percentage body fat estimations by BEI. Multiple regression analysis showed that BMI and BEI together gave the best prediction of total body fat as measured on MRI from the equation: TBF-MRI=-25277.77+1457.61(BMI)+423.95(%fat-BEI), with R2=0.89. Percentage body fat measurement from MRI, BEI and skinfold were not significantly different but their results were not interchangeable. Linear regression of %body fat from MRI on those obtained from BEI and skinfold measurements showed a modest fit with R2=0.6973 and 0.5501, respectively. In children 8-12 years old, BMI gives a good estimation of the total body fat as measured on MRI. The estimation will be improved when both BEI and BMI are used in the prediction. Bioelectrical impedance has a low correlation with total body fat and its use alone in estimating total body fat is not recommended. Skinfold measurement also gives a reasonably good prediction of total body fat and addition of BMI and BEI does not improve the prediction. Both BEI and skinfold measurements give a modest prediction of %body fat measured by MRI method.