Hara T, Tanck E, Homminga J, Huiskes R
Orthopaedic Research Lab, University of Nijmegen, Nijmegen, The Netherlands.
Bone. 2002 Jul;31(1):107-9. doi: 10.1016/s8756-3282(02)00782-2.
In this study, we investigate how morphological parameters and mechanical properties derived from microcomputed tomography (microCT) are affected by small errors in threshold value when variable bone structures and different bone volume fractions are involved. For this purpose, biopsies of vertebrae of 6-, 23-, and 230-week-old female pigs were scanned using microCT. For each specimen, five threshold values were determined within the range of thresholds that an observer could select realistically, in steps of 0.5%. The scans were converted to microfinite-element (microFE) models, used to determine the elastic moduli. A variation of 0.5% in threshold resulted in a 5% difference in bone volume fraction and 9% difference in maximal stiffness for bone cubes with a volume fraction of <0.15. When the volume fraction was >0.2, these differences were only 2% and 3%, respectively. For all bone cubes, the differences for trabecular thickness and bone surface density were <3%. The effects on morphological anisotropy and trabecular number were negligible for threshold variations of 0.5%. These findings suggest that threshold selection is important for the accurate determination of volume fraction and mechanical properties, especially for low bone volume fractions; the architectural directionality is less sensitive to changes in threshold.
在本研究中，我们探究了在涉及可变骨结构和不同骨体积分数时，源自微型计算机断层扫描（microCT）的形态学参数和力学性能如何受到阈值小误差的影响。为此，使用microCT对6周龄、23周龄和230周龄雌性猪的椎骨活检样本进行扫描。对于每个样本，在观察者实际可选择的阈值范围内，以0.5%的步长确定五个阈值。将扫描结果转换为微观有限元（microFE）模型，用于确定弹性模量。对于体积分数<0.15的骨立方体，阈值变化0.5%会导致骨体积分数有5%的差异以及最大刚度有9%的差异。当体积分数>0.2时，这些差异分别仅为2%和3%。对于所有骨立方体，小梁厚度和骨表面密度的差异<3%。对于0.5%的阈值变化，对形态各向异性和小梁数量的影响可忽略不计。这些发现表明，阈值选择对于准确确定体积分数和力学性能很重要，尤其是对于低骨体积分数；结构方向性对阈值变化不太敏感。
