Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy.
Med Eng Phys. 2011 Jan;33(1):112-20. doi: 10.1016/j.medengphy.2010.09.014. Epub 2010 Oct 30.
Various papers described mesh morphing techniques for computational biomechanics, but none of them provided a quantitative assessment of generality, robustness, automation, and accuracy in predicting strains. This study aims to quantitatively evaluate the performance of a novel mesh-morphing algorithm. A mesh-morphing algorithm based on radial-basis functions and on manual selection of corresponding landmarks on template and target was developed. The periosteal geometries of 100 femurs were derived from a computed tomography scan database and used to test the algorithm generality in producing finite element (FE) morphed meshes. A published benchmark, consisting of eight femurs for which in vitro strain measurements and standard FE model strain prediction accuracy were available, was used to assess the accuracy of morphed FE models in predicting strains. Relevant parameters were identified to test the algorithm robustness to operative conditions. Time and effort needed were evaluated to define the algorithm degree of automation. Morphing was successful for 95% of the specimens, with mesh quality indicators comparable to those of standard FE meshes. Accuracy of the morphed meshes in predicting strains was good (R(2)>0.9, RMSE%<10%) and not statistically different from the standard meshes (p-value=0.1083). The algorithm was robust to inter- and intra-operator variability, target geometry refinement (p-value>0.05) and partially to the number of landmark used. Producing a morphed mesh starting from the triangularized geometry of the specimen requires on average 10 min. The proposed method is general, robust, automated, and accurate enough to be used in bone FE modelling from diagnostic data, and prospectively in applications such as statistical shape modelling.
各种文献都描述了计算生物力学中的网格变形技术，但没有一篇文献对通用性、鲁棒性、自动化和预测应变的准确性进行定量评估。本研究旨在定量评估一种新型网格变形算法的性能。开发了一种基于径向基函数和在模板和目标上手动选择相应标志点的网格变形算法。从计算机断层扫描数据库中提取了 100 根股骨的骨膜几何形状，并将其用于测试算法在生成有限元（FE）变形网格方面的通用性。使用了一个已发表的基准，其中包括 8 根股骨，这些股骨具有体外应变测量和标准 FE 模型应变预测准确性的可用数据，以评估变形 FE 模型在预测应变方面的准确性。确定了相关参数来测试算法对手术条件的鲁棒性。评估了所需的时间和精力，以确定算法的自动化程度。95%的标本成功进行了变形，网格质量指标与标准 FE 网格相当。变形网格在预测应变方面的准确性良好（R(2)>0.9，RMSE%<10%），与标准网格无统计学差异（p 值=0.1083）。该算法对操作者间和操作者内的变异性、目标几何形状的细化（p 值>0.05）以及部分标志点的数量具有鲁棒性。从标本的三角化几何形状开始生成变形网格平均需要 10 分钟。所提出的方法具有通用性、鲁棒性、自动化和足够的准确性，可用于从诊断数据进行骨骼 FE 建模，并有望在统计形状建模等应用中使用。
