School of Kinesiology, University of Minnesota, Minneapolis, MN, 55455, USA.
School of Kinesiology, University of Minnesota, Minneapolis, MN, 55455, USA.
Clin Nutr ESPEN. 2023 Jun;55:185-190. doi: 10.1016/j.clnesp.2023.03.014. Epub 2023 Mar 24.
BACKGROUND & AIMS: Dual X-ray absorptiometry (DXA) software allows for total and regional (i.e., arms and legs) assessment of body composition, with recent advancements allowing for DXA derived volume. The use of DXA derived volume allows for the development of a convenient four-compartment model to accurately measure body composition. The purpose of the current study is to evaluate the validity of a regional DXA derived four-compartment model.
A total of 30 males and females underwent one whole body DXA scan, underwater weighing, total and regional bioelectrical impedance spectroscopy, and regional measures of water displacement. Manually created region of interest boxes assessed regional DXA body composition. Linear regression models with fat mass from the DXA as the dependent variable and body volume from water displacement, total body water from bioelectrical impedance spectroscopy, and DXA bone mineral and body mass as independent variables created regional four-compartment models. Measures of fat-free mass and percent fat were calculated using the four-compartment derived fat mass. T-tests assessed DXA derived four-compartment model to the traditional four-compartment model with volume assessed by water displacement. Regression models were cross-validated using the Repeated k-fold Cross Validation method.
Arm and leg regional DXA derived four-compartment model for fat mass (p = 0.999, both arm and leg), fat-free mass (p = 0.999, both arm and leg), and percent fat (arm: p = 0.766; leg: p = 0.938) were not significantly different from the regional four-compartment model with regional volume measured via water displacement. Cross-validation of each model produced R values of 0.669 for the arm and 0.783 for the leg.
The DXA can be used to create four-compartment model for estimating total and regional fat mass, fat-free mass, and percent fat. Therefore, these results allow for a convenient regional four-compartment model with DXA derived regional volume.
双能 X 线吸收法（DXA）软件允许对身体成分进行总体和局部（即手臂和腿部）评估，最近的进展允许进行 DXA 衍生体积。DXA 衍生体积的使用允许开发一个方便的四室模型，以准确测量身体成分。本研究的目的是评估局部 DXA 衍生四室模型的有效性。
总共 30 名男性和女性接受了一次全身 DXA 扫描、水下称重、全身和局部生物电阻抗光谱法以及局部水分置换测量。手动创建感兴趣区域框评估局部 DXA 身体成分。以 DXA 中的脂肪质量为因变量，以水分置换中的身体体积、生物电阻抗光谱法中的全身总水量和 DXA 骨矿物质和体重为自变量，建立局部四室模型的线性回归模型。使用四室衍生脂肪质量计算无脂肪质量和脂肪百分比。使用 t 检验评估 DXA 衍生四室模型与通过水分置换评估体积的传统四室模型。使用重复 k 折交叉验证方法对回归模型进行交叉验证。
手臂和腿部局部 DXA 衍生四室模型的脂肪质量（p=0.999，手臂和腿部）、无脂肪质量（p=0.999，手臂和腿部）和脂肪百分比（手臂：p=0.766；腿部：p=0.938）与通过水分置换测量的局部四室模型无显著差异。对每个模型进行的交叉验证产生了手臂的 R 值为 0.669 和腿部的 R 值为 0.783。
DXA 可用于创建四室模型，以估计全身和局部脂肪质量、无脂肪质量和脂肪百分比。因此，这些结果允许使用 DXA 衍生的局部体积方便地构建局部四室模型。
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