Lu Yongtao, Boudiffa Maya, Dall'Ara Enrico, Bellantuono Ilaria, Viceconti Marco
Department of Engineering Mechanics, Dalian University of Technology, Dalian, China; Department of Mechanical Engineering and INSIGNEO Institute for in Silico Medicine, the University of Sheffield, Sheffield, UK.
Department of Oncology and Metabolism and INSIGNEO Institute for in Silico Medicine, University of Sheffield, Sheffield, UK.
J Biomech. 2016 Jul 5;49(10):2095-2099. doi: 10.1016/j.jbiomech.2016.05.022. Epub 2016 May 25.
In vivo micro-computed tomography (µCT) scanning of small rodents is a powerful method for longitudinal monitoring of bone adaptation. However, the life-time bone growth in small rodents makes it a challenge to quantify local bone adaptation. Therefore, the aim of this study was to develop a protocol, which can take into account large bone growth, to quantify local bone adaptations over space and time. The entire right tibiae of eight 14-week-old C57BL/6J female mice were consecutively scanned four times in an in vivo µCT scanner using a nominal isotropic image voxel size of 10.4µm. The repeated scan image datasets were aligned to the corresponding baseline (first) scan image dataset using rigid registration. 80% of tibia length (starting from the endpoint of the proximal growth plate) was selected as the volume of interest and partitioned into 40 regions along the tibial long axis (10 divisions) and in the cross-section (4 sectors). The bone mineral content (BMC) was used to quantify bone adaptation and was calculated in each region. All local BMCs have precision errors (PE%CV) of less than 3.5% (24 out of 40 regions have PE%CV of less than 2%), least significant changes (LSCs) of less than 3.8%, and 38 out of 40 regions have intraclass correlation coefficients (ICCs) of over 0.8. The proposed protocol allows to quantify local bone adaptations over an entire tibia in longitudinal studies, with a high reproducibility, an essential requirement to reduce the number of animals to achieve the necessary statistical power.
对小型啮齿动物进行体内微型计算机断层扫描（µCT）是纵向监测骨骼适应性的有力方法。然而，小型啮齿动物一生的骨骼生长使得量化局部骨骼适应性成为一项挑战。因此，本研究的目的是开发一种方案，该方案可以考虑到较大的骨骼生长，以便在空间和时间上量化局部骨骼适应性。使用标称各向同性图像体素大小为10.4µm的体内µCT扫描仪，对八只14周龄C57BL/6J雌性小鼠的整个右胫骨连续扫描四次。使用刚性配准将重复扫描图像数据集与相应的基线（第一次）扫描图像数据集对齐。选择胫骨长度的80%（从近端生长板的端点开始）作为感兴趣体积，并沿胫骨长轴（10个分区）和横截面（4个扇区）划分为40个区域。使用骨矿物质含量（BMC）来量化骨骼适应性，并在每个区域进行计算。所有局部BMC的精度误差（PE%CV）均小于3.5%（40个区域中的24个区域的PE%CV小于2%），最小显著变化（LSCs）小于3.8%，40个区域中的38个区域的组内相关系数（ICCs）超过0.8。所提出的方案允许在纵向研究中量化整个胫骨的局部骨骼适应性，具有高重现性，这是减少动物数量以获得必要统计效力的一项基本要求。
