Manske Sarah L, Davison Erin M, Burt Lauren A, Raymond Duncan A, Boyd Steven K
McCaig Institute for Bone and Joint Health and Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary, Canada.
J Bone Miner Res. 2017 Jul;32(7):1514-1524. doi: 10.1002/jbmr.3128. Epub 2017 Apr 5.
Second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) provides the highest resolution in vivo to assess bone density and microarchitecture in 3D. Although strong agreement of most outcomes measured with first- (XCTI) and second- (XCTII) generation HR-pQCT has been demonstrated, the ability to use the two systems interchangeably is unknown. From in vivo measurements, we determined the limits of estimating XCTII data from XCTI scans conducted in vivo and whether that estimation can be improved by linear cross-calibration equations. These data are crucial as the research field transitions to the new technology. Our study design established cross-calibration equations by scanning 62 individuals on both systems on the same day and then tested those cross-calibrations on the same cohort 6 months later so that estimated (denoted as XCTII*) and "true" XCTII parameters could be compared. We calculated the generalized least-significant change (GLSC) for those predictions. There was strong agreement between both systems for density (R > 0.94), macroarchitecture (R > 0.95), and most microarchitecture outcomes with the exception of trabecular thickness (Tb.Th, R = 0.51 to 0.67). Linear regression equations largely eliminated the systematic error between XCTII and XCTII* and produced a good estimation of most outcomes, with individual error estimates between 0.2% and 3.4%, with the exception of Tt.BMD. Between-system GLSC was similar to within-XCTI LSC (eg, 8.3 to 41.9 mg HA/cm for density outcomes). We found that differences between outcomes assessed with XCTI and XCTII can be largely eliminated by cross-calibration. Tb.Th is poorly estimated because it is measured more accurately by XCTII than XCTI. It may be possible to use cross-calibration for most outcomes when both scanner generations are used for multicenter and longitudinal studies. © 2017 American Society for Bone and Mineral Research.
第二代高分辨率外周定量计算机断层扫描（HR-pQCT）在体内提供了最高分辨率，以三维方式评估骨密度和微观结构。尽管已证明第一代（XCTI）和第二代（XCTII）HR-pQCT测量的大多数结果具有高度一致性，但这两种系统能否互换使用尚不清楚。通过体内测量，我们确定了从体内进行的XCTI扫描估计XCTII数据的限度，以及该估计是否可以通过线性交叉校准方程得到改善。随着研究领域向新技术过渡，这些数据至关重要。我们的研究设计通过在同一天对62名个体在两个系统上进行扫描来建立交叉校准方程，然后在6个月后对同一队列测试这些交叉校准，以便比较估计的（表示为XCTII*）和“真实”的XCTII参数。我们计算了这些预测的广义最小显著变化（GLSC）。两个系统在密度（R ＞0.94）、宏观结构（R ＞0.95）以及除小梁厚度（Tb.Th，R = 0.51至0.67）外的大多数微观结构结果方面具有高度一致性。线性回归方程在很大程度上消除了XCTII和XCTII*之间的系统误差，并对大多数结果产生了良好的估计，个体误差估计在0.2%至3.4%之间，Tt.BMD除外。系统间GLSC与XCTI内LSC相似（例如，密度结果为8.3至41.9 mg HA/cm）。我们发现，通过交叉校准可以在很大程度上消除XCTI和XCTII评估结果之间的差异。Tb.Th估计不佳，因为XCTII比XCTI测量得更准确。当两代扫描仪都用于多中心和纵向研究时，对于大多数结果可能可以使用交叉校准。© 2017美国骨与矿物质研究学会
