Body composition by DXA: tried and true?

Area of Science:

• Biomedical Engineering
• Human Physiology
• Radiology

Background:

• Dual-energy x-ray absorptiometry (DXA) is the standard for bone mass assessment.
• Modern DXA instruments can also measure soft tissue mass, enabling a three-compartment body composition model (bone mineral, fat, bone-free lean mass).
• Hydrodensitometry, traditionally a reference method for body composition, relies on assumptions about fat-free mass that may not hold true across all populations.

Purpose of the Study:

• To evaluate the potential of DXA as a reference method for body composition assessment.
• To compare the accuracy of DXA with hydrodensitometry across diverse populations.
• To identify factors limiting DXA's current validity as a criterion method.

Main Methods:

• Review of existing literature on DXA and hydrodensitometry for body composition analysis.
• Analysis of DXA's reliance on assumptions compared to hydrodensitometry.
• Examination of precision and accuracy data for DXA measurements.
• Investigation of variability in DXA instrument calibration, data acquisition, and analysis.

Main Results:

• DXA provides precise body composition measurements.
• DXA may be less assumption-dependent than hydrodensitometry, suggesting potential for broader population applicability.
• Significant variability exists among DXA manufacturers in calibration and data processing methods.
• The accuracy of DXA measurements across populations remains questionable.

Conclusions:

• While DXA demonstrates high precision for body composition, its accuracy as a reference method requires further validation.
• Variability in DXA technology across manufacturers hinders its universal adoption as a criterion standard.
• Current evidence suggests that endorsing DXA as the definitive reference method for body composition is premature.