Nana Alisa, Slater Gary J, Hopkins Will G, Burke Louise M
AIS Sports Nutrition, Australian Institute of Sport, Canberra, ACT, Australia.
Int J Sport Nutr Exerc Metab. 2012 Oct;22(5):313-22. doi: 10.1123/ijsnem.22.5.313.
Dual-energy X-ray absorptiometry (DXA) is becoming a popular tool to measure body composition, owing to its ease of operation and comprehensive analysis. However, some people, especially athletes, are taller and/or broader than the active scanning area of the DXA bed and must be scanned in sections. The aim of this study was to investigate the reliability of DXA measures of whole-body composition summed from 2 or 3 partial scans. Physically active young adults (15 women, 15 men) underwent 1 whole-body and 4 partial DXA scans in a single testing session under standardized conditions. The partial scanning areas were head, whole body from the bottom of the chin down, and right and left sides of the body. Body-composition estimates from whole body were compared with estimates from summed partial scans to simulate different techniques to accommodate tall and/or broad subjects relative to the whole-body scan. Magnitudes of differences in the estimates were assessed by standardization. In simulating tall subjects, summation of partial scans that included the head scan overestimated whole-body composition by ~3 kg of lean mass and ~1 kg of fat mass, with substantial technical error of measurement. In simulating broad subjects, summation of right and left body scans produced no substantial differences in body composition than those of the whole-body scan. Summing partial DXA scans provides accurate body-composition estimates for broad subjects, but other strategies are needed to accommodate tall subjects.
双能X线吸收法（DXA）因其操作简便且分析全面，正成为一种常用的身体成分测量工具。然而，有些人，尤其是运动员，身高较高和/或体型较宽，超出了DXA检查床的有效扫描区域，必须进行分段扫描。本研究的目的是探讨通过2次或3次局部扫描汇总得出的DXA全身成分测量结果的可靠性。身体健康的年轻成年人（15名女性，15名男性）在标准化条件下，于单次测试中接受1次全身和4次局部DXA扫描。局部扫描区域包括头部、从下巴底部向下的全身以及身体的左右两侧。将全身的身体成分估计值与汇总局部扫描的估计值进行比较，以模拟不同技术来适应相对于全身扫描而言身高较高和/或体型较宽的受试者。通过标准化评估估计值差异的大小。在模拟高个子受试者时，包含头部扫描的局部扫描汇总结果高估了全身成分， lean mass约高估3千克，脂肪量约高估1千克，测量技术误差较大。在模拟体型较宽的受试者时，身体左右两侧扫描结果汇总得出的身体成分与全身扫描结果相比无显著差异。汇总局部DXA扫描可为体型较宽的受试者提供准确的身体成分估计值，但对于高个子受试者则需要其他策略。
