de Bakker Chantal M J, Altman Allison R, Li Connie, Tribble Mary Beth, Lott Carina, Tseng Wei-Ju, Liu X Sherry
McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 426C Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA, 19104, USA.
Ann Biomed Eng. 2016 Aug;44(8):2518-2528. doi: 10.1007/s10439-015-1527-9. Epub 2016 Jan 19.
In vivo µCT imaging allows for high-resolution, longitudinal evaluation of bone properties. Based on this technology, several recent studies have developed in vivo dynamic bone histomorphometry techniques that utilize registered µCT images to identify regions of bone formation and resorption, allowing for longitudinal assessment of bone remodeling. However, this analysis requires a direct voxel-by-voxel subtraction between image pairs, necessitating rotation of the images into the same coordinate system, which introduces interpolation errors. We developed a novel image transformation scheme, matched-angle transformation (MAT), whereby the interpolation errors are minimized by equally rotating both the follow-up and baseline images instead of the standard of rotating one image while the other remains fixed. This new method greatly reduced interpolation biases caused by the standard transformation. Additionally, our study evaluated the reproducibility and precision of bone remodeling measurements made via in vivo dynamic bone histomorphometry. Although bone remodeling measurements showed moderate baseline noise, precision was adequate to measure physiologically relevant changes in bone remodeling, and measurements had relatively good reproducibility, with intra-class correlation coefficients of 0.75-0.95. This indicates that, when used in conjunction with MAT, in vivo dynamic histomorphometry provides a reliable assessment of bone remodeling.
体内微计算机断层扫描（µCT）成像能够对骨特性进行高分辨率的纵向评估。基于这项技术，最近的几项研究开发了体内动态骨组织形态计量学技术，该技术利用配准的µCT图像来识别骨形成和吸收区域，从而能够对骨重塑进行纵向评估。然而，这种分析需要在图像对之间进行逐体素的直接减法运算，这就需要将图像旋转到相同的坐标系中，而这会引入插值误差。我们开发了一种新颖的图像变换方案，即匹配角度变换（MAT），通过对后续图像和基线图像进行同等旋转，而不是像标准方法那样只旋转一幅图像而另一幅保持固定，从而将插值误差降至最低。这种新方法极大地减少了由标准变换引起的插值偏差。此外，我们的研究评估了通过体内动态骨组织形态计量学进行的骨重塑测量的可重复性和精度。尽管骨重塑测量显示出适度的基线噪声，但精度足以测量骨重塑中生理相关的变化，并且测量具有相对较好的可重复性，组内相关系数为0.75 - 0.95。这表明，当与MAT结合使用时，体内动态组织形态计量学能够对骨重塑进行可靠的评估。
