The Department of Biochemistry and Experimental Medicine, The Children's Memorial Health Institute, Warsaw, Poland.
The Department of Biochemistry and Experimental Medicine, The Children's Memorial Health Institute, Warsaw, Poland.
J Clin Densitom. 2010 Jan-Mar;13(1):84-95. doi: 10.1016/j.jocd.2009.11.001.
The replacement of the old dual-energy X-ray absorptiometry system with a novel one should be preceded by a cross-calibration procedure. Therefore, the study was aimed at investigating the consistency of bone and body composition measures performed in pediatric population using pencil beam (DPX-L; GE Healthcare, GE Healthcare, Madison, WI) and fan beam (Prodigy; GE Healthcare, GE Healthcare, Madison, WI) densitometers. The study group consisted of 212 healthy children aged 4-18yr. Total body (TB) and lumbar spine (S) (L2-L4) measurements were performed using DPX-L and Prodigy during the same visit. Bland-Altman analysis, linear regressions, and paired t-test were performed to evaluate the consistency of measurements and to establish a cross-calibration equation. The average Prodigy values for TB and lumbar spine bone mineral density (BMD) and content (BMC) were 2.7%, 2.4% and 1.6%, 1.6% higher than those of DPX-L, respectively (p<0.0001). Prodigy-assessed bone area (BA) was lower by 1.4% for TBBA (p<0.0001) and 1.1% for SBA (p<0.001). Lean body mass (LBM) from Prodigy was higher by 6.9% (p<0.0001), whereas fat mass (FM) was lower by 8.4% compared with those from DPX-L (p<0.0001). Bland-Altman analyses revealed the effect of magnitude that was nonlinear (2nd degree polynomial) for TBBMD (r=0.32, p=0.001), TBBMC (r=0.51, p<0.0001), TBBA (r=0.34, p<0.0001), and LBM (r=0.56, p<0.0001), but not for FM (r=0.14, not significant [n.s.]). In contrast, in lumbar spine, the magnitude dependence was linear and significant for SBMC (r=0.46, p<0.0001) and SBA (r=0.34, p<0.0001) but not for SBMD (r=0.12, n.s.). Both skeletal and body composition variables assessed by DPX-L and Prodigy devices were highly correlated, showing R(2) values ranging from 0.976 for FM to 0.994 for SBMC. The results of this study document a necessity for implementation of calculated cross-calibration equations to transform DPX-L-based local pediatric references into a novel Prodigy system.
用新型双能 X 射线吸收仪（Dual-Energy X-ray Absorptiometry，DXA）替换旧设备时，应先进行交叉校准程序。因此，本研究旨在调查使用笔形束（DPX-L；GE 医疗保健，GE 医疗保健，麦迪逊，威斯康星州）和扇形束（Prodigy；GE 医疗保健，GE 医疗保健，麦迪逊，威斯康星州）密度仪对儿科人群进行骨和身体成分测量的一致性。研究组包括 212 名 4-18 岁的健康儿童。在同一访问期间，使用 DPX-L 和 Prodigy 对全身（TB）和腰椎（S）（L2-L4）进行测量。使用 Bland-Altman 分析、线性回归和配对 t 检验来评估测量的一致性并建立交叉校准方程。Prodigy 评估的全身骨矿物质密度（BMD）和含量（BMC）的平均 Prodigy 值分别比 DPX-L 高 2.7%、2.4%和 1.6%、1.6%（p<0.0001）。对于全身骨面积（BA），Prodigy 评估值低 1.4%（p<0.0001），对于腰椎 BA 低 1.1%（p<0.001）。Prodigy 评估的瘦体重（LBM）高 6.9%（p<0.0001），而脂肪量（FM）低 8.4%（p<0.0001）。Bland-Altman 分析显示，TB 骨矿物质密度（BMD）（r=0.32，p=0.001）、TB 骨矿物质含量（BMC）（r=0.51，p<0.0001）、TBBA（r=0.34，p<0.0001）和 LBM（r=0.56，p<0.0001）的效应存在非线性（二次多项式），但 FM（r=0.14，不显著[n.s.]）不存在。相比之下，在腰椎中，SBMC（r=0.46，p<0.0001）和 SBA（r=0.34，p<0.0001）的大小依赖性呈线性，而 SBMD（r=0.12，n.s.）则没有。DPX-L 和 Prodigy 设备评估的骨骼和身体成分变量高度相关，显示出从脂肪量（FM）的 0.976 到腰椎 BMC 的 0.994 的 R2 值。本研究的结果证明需要实施计算交叉校准方程，以便将基于 DPX-L 的本地儿科参考值转换为新型 Prodigy 系统。
