Accuracy of quantitative magnetic resonance and eight-electrode bioelectrical impedance analysis in normal weight and obese women.

• Background & aims Quantitative magnetic resonance (QMR) has previously been shown to both overestimate and underestimate average fat mass (FM) in humans. Eight-electrode bioelectrical impedance analysis (BIA) has previously been found biased as well as successfully validated. We report cross-sectional accuracy of QMR and eight-electrode BIA evaluated with air displacement plethysmography (ADP) as reference method. Methods Fat mass and fat free mass (FFM) by QMR and eight-electrode BIA were evaluated against ADP as reference in 38 normal weight and 30 obese women. Total body water estimates by QMR and eight-electrode BIA were compared. Results Fat mass was overestimated by QMR (1 ± 2 kg, p < 0.001) and was underestimated by eight-electrode BIA (1 ± 3 kg, p = 0.03, Bonferroni adjusted p = 0.29) in normal weight women. Fat mass was underestimated by both QMR (2 ± 2 kg, p < 0.001) and eight-electrode BIA (9 ± 3 kg, p < 0.001) in obese women. Fat free mass biases were of similar magnitude but in opposite direction to FM biases. Total body water estimates were larger by eight-electrode BIA compared to QMR (1–10 kg). Conclusions Fat mass and FFM by QMR were both biased but in opposite directions in both normal weight and obese women. Eight-electrode BIA FM and FFM estimates were imprecise and biased in obese women. Thus, QMR is more precise and more accurate than eight-electrode BIA for estimating body composition in women, but is not accurate enough to be used for individual single assessment of body composition.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Nyckelord

body composition

obesity

quantitative magnetic resonance

bioelectrical analysis

air displacement pletysmography

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