CREATIS, UMR CNRS, Villeurbanne, France.
Med Phys. 2010 Aug;37(8):4364-76. doi: 10.1118/1.3447728.
Trabecular bone microarchitecture is made of a complex network of plate and rod structures evolving with age and disease. The purpose of this article is to propose a new 3D local analysis method for the quantitative assessment of parameters related to the geometry of trabecular bone microarchitecture.
The method is based on the topologic classification of the medial axis of the 3D image into branches, rods, and plates. Thanks to the reversibility of the medial axis, the classification is next extended to the whole 3D image. Finally, the percentages of rods and plates as well as their mean thicknesses are calculated. The method was applied both to simulated test images and 3D micro-CT images of human trabecular bone.
The classification of simulated phantoms made of plates and rods shows that the maximum error in the quantitative percentages of plate and rods is less than 6% and smaller than with the structure model index (SMI). Micro-CT images of human femoral bone taken in osteoporosis and early or advanced osteoarthritis were analyzed. Despite the large physiological variability, the present method avoids the underestimation of rods observed with other local methods. The relative percentages of rods and plates were not significantly different between osteoarthritis and osteoporotic groups, whereas their absolute percentages were in relation to an increase of rod and plate thicknesses in advanced osteoarthritis with also higher relative and absolute number of nodes.
The proposed method is model-independent, robust to surface irregularities, and enables geometrical characterization of not only skeletal structures but entire 3D images. Its application provided more accurate results than the standard SMI on simple simulated phantoms, but the discrepancy observed on the advanced osteoarthritis group raises questions that will require further investigations. The systematic use of such a local method in the characterization of trabecular bone samples could provide new insight in bone microarchitecture changes related to bone diseases or to those induced by drugs or therapy.
小梁骨微观结构由板和杆结构的复杂网络组成，这些结构随着年龄和疾病而演变。本文的目的是提出一种新的 3D 局部分析方法，用于定量评估与小梁骨微观结构几何形状相关的参数。
该方法基于对 3D 图像中中轴的拓扑分类，将其分为分支、杆和板。由于中轴的可逆性，分类可以扩展到整个 3D 图像。最后，计算杆和板的百分比及其平均厚度。该方法既应用于模拟测试图像，也应用于人类小梁骨的 3D 微 CT 图像。
由板和杆组成的模拟幻像的分类表明，板和杆的定量百分比的最大误差小于 6%，并且小于结构模型指数（SMI）。分析了骨质疏松症和早期或晚期骨关节炎患者的股骨微 CT 图像。尽管存在较大的生理变异性，但本方法避免了其他局部方法观察到的杆低估。关节炎和骨质疏松症组之间，杆和板的相对百分比没有显著差异，而它们的绝对百分比与杆和板厚度的增加有关，在晚期关节炎中也有更高的相对和绝对节点数。
所提出的方法是模型独立的，对表面不规则性具有鲁棒性，不仅可以对骨骼结构进行几何特征描述，还可以对整个 3D 图像进行描述。它在简单模拟幻像上的应用比标准 SMI 提供了更准确的结果，但在晚期关节炎组中观察到的差异提出了需要进一步研究的问题。在小梁骨样本的特征描述中系统地使用这种局部方法，可以为与骨骼疾病或药物或治疗引起的骨骼微结构变化相关的新见解提供新的见解。
