MacNeil Joshua A, Boyd Steven K
Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada.
Med Eng Phys. 2008 Jul;30(6):792-9. doi: 10.1016/j.medengphy.2007.11.003. Epub 2008 Mar 4.
A human high-resolution peripheral quantitative computed tomography scanner (HR-pQCT) (XtremeCT, Scanco Medical, Switzerland) capable of measuring three important indicators of bone quality (micro-architectural morphology, mineralization and mechanical stiffness) has been developed. The goal of this study was to evaluate the reproducibility of male and female HR-pQCT in vivo measurements, and elucidate the causes of error in these measurements through a comparison with in vitro measurements. The best possible short-term reproducibility was found using a set of 10 in vitro measurements without repositioning, and a set of 10 with repositioning. Subsequently, in vivo measurements were performed on 15 male and 15 female subjects at baseline and follow-ups of 1 week and 4 months to determine the short- and long-term reproducibility of the system. In addition to the 2D area matching method used in the standard evaluation protocol, a custom developed 3D registration method was used to find the common region between repeated scans. The best possible reproducibility without movement artifacts and repositioning error was less than 0.5%, while the reproducibility with repositioning error was less than 1.5%. The in vivo reproducibility of density (<1%), morphological (<4.5%) and stiffness (<3.5) measurements was consistently poorer than the reproducibility of cadaver measurements, presumably due to small movement artifacts and repositioning errors. Using 3D image registration, repositioning error was reduced on average by 23% and 8% for measurements of the radius and tibia sites, respectively. This study has provided bounds for the reproducibility of HR-pQCT to monitor bone quality longitudinally, and a basis for clinical study design to determine detectable changes.
一种能够测量骨质量的三个重要指标（微观结构形态、矿化和机械刚度）的人体高分辨率外周定量计算机断层扫描扫描仪（HR-pQCT）（XtremeCT，瑞士斯堪科医疗公司）已被开发出来。本研究的目的是评估男性和女性HR-pQCT体内测量的可重复性，并通过与体外测量进行比较来阐明这些测量中的误差原因。使用一组10次无重新定位的体外测量和一组10次有重新定位的体外测量，发现了最佳的短期可重复性。随后，对15名男性和15名女性受试者在基线以及1周和4个月的随访时进行体内测量，以确定该系统的短期和长期可重复性。除了标准评估方案中使用的二维面积匹配方法外，还使用了一种定制开发的三维配准方法来找到重复扫描之间的共同区域。无运动伪影和重新定位误差时的最佳可重复性小于0.5%，而有重新定位误差时的可重复性小于1.5%。密度（<1%）、形态（<4.5%）和刚度（<3.5）测量的体内可重复性始终比尸体测量的可重复性差，这可能是由于小的运动伪影和重新定位误差所致。使用三维图像配准，桡骨和胫骨部位测量的重新定位误差分别平均降低了23%和8%。本研究为HR-pQCT纵向监测骨质量的可重复性提供了界限，并为确定可检测变化的临床研究设计提供了依据。
