Location: Arkansas Children's Nutrition CenterTitle: The use of NMR for infant body composition, comparison with DXA and chemical analysis) Author
Submitted to: Obesity
Publication Type: Abstract Only
Publication Acceptance Date: 6/19/2009
Publication Date: 11/15/2009
Citation: Andres, A., Shankar, K., Mitchell, A.D., Badger, T.M. 2009. The use of NMR for infant body composition, comparison with DXA and chemical analysis [abstract]. Obesity. 17(S2):S61. Interpretive Summary:
Technical Abstract: Childhood obesity is susceptible to programming during the early stages of development (in utero and/or during the first year of life). Obtaining accurate and precise measures of body composition (BC) in infants and children and through adulthood is critical to testing these hypotheses in both cross-sectional and longitudinal studies. Until now, current technology has made the measurement of body fat and fat-free mass challenging in infants and children. BC cannot be evaluated with Air Displacement Plethysmography (ADP) between ages 6 mo and 6 y, making it impossible to obtain longitudinal data sets. Dual-energy X-ray Absorptiometry (DXA) can be used longitudinally, but the requirement for stillness and the exposure to radiation limit its use in pediatric populations. Nuclear Magnetic Resonance (NMR) has been previously used in animals and human adults to obtain accurate and precise measures of body fat and fat free mass. In the current study, we assessed a device specially designed to accommodate infants and children between 3 and 50 kg (EchoMRI-AH, Echo Medical Systems, CA). BC of 50 pigs (3 to 50 kg) was obtained using DXA and NMR (5 scans/piglet for each method) and compared against standard whole body chemical analysis. NMR fat mass was highly correlated to DXA and chemical fat mass (r=0.97, P<0.01 and r=0.98, P<0.01, respectively). NMR fat free mass was also highly correlated to DXA fat-free mass (r=0.99, P<0.01). In addition, NMR total body water was very similar to the results obtained using chemical analysis (r=0.999, P<0.01). In a cross-sectional study, ADP, DXA and NMR measures were obtained in 82 infants and children aged 2 mo to 6 y. In infants (0-6mo, N=56) ADP and NMR fat (r=0.93, p<0.01) and fat free (r=0.94 p<0.01) mass were highly correlated. In infants (0-1y, N=21), DXA and NMR fat (r=0.78, P<0.01) and fat-free (r=0.82, P<0.01) mass were also significantly correlated despite our lower sample size. In children (2-6y, N=52), DXA and NMR fat (r=0.96, P<0.01) and fat-free (r=0.98, P<0.01) mass were highly correlated, suggesting that our lower sample size during the first year of life may be responsible for the lower, although significant, correlation coefficient. According to these data, NMR is a precise, accurate and reliable method of body composition that will allow longitudinal data collection in infants and children without any exposure to radiation.