Can a partial volume edge effect reduction algorithm improve the repeatability of subject-specific finite element models of femurs obtained from CT data?
Can a partial volume edge effect reduction algorithm improve the repeatability of subject-specific finite element models of femurs obtained from CT data?
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DOI：
10.1080/10255842.2012.673595
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发表时间：
2014-02-17
影响因子：
1.6
通讯作者：
Whyne, Cari
中科院分区：
文献类型：
--
作者：
Peleg, Eran;Herblum, Ryan;Whyne, Cari
患者特定有限元（FE）建模的可靠性取决于提供可重复分析的能力。操作员间生成的网格的差异可能会在所需位置产生应变和应力读数的变化，由于部分体积边缘效应（PVEE），这些读数在模型表面被放大。在这项研究中，引入了一种新的方法的基础上，内部开发的算法，调整模型的表面节点的位置，以一致的预定义阈值亨氏单位值。三具尸体的人股骨标本进行CT扫描，并创建表面模型后，由三个不同的经验丰富的操作员半自动分割。对每个模型进行了有限元分析，应用和不应用表面调整算法（共18个模型），实现相同的边界条件。在通常用于实验应变计测量确认的位置处，对三个样本中每个样本的六个生成模型的六个等效表面节点处的最大主应变和应力以及空间坐标进行了探测。进行Wilcoxon符号秩检验，以确定操作员间变异性和PVEE调整算法的影响。应用调整算法后，应力值的平均术者间差异显著降低（之前：3.32 +/-4.35 MPa，之后：1.47 +/-1.77 MPa，p=0.025）。应变值对术中变异性不太敏感（p=0.286）。总之，本研究中提出的新方法可以提供一种方法来提高从CT数据获得的骨的受试者特定FE模型的可重复性。
The reliability of patient-specific finite element (FE) modelling is dependent on the ability to provide repeatable analyses. Differences of inter-operator generated grids can produce variability in strain and stress readings at a desired location, which are magnified at the surface of the model as a result of the partial volume edge effects (PVEEs). In this study, a new approach is introduced based on an in-house developed algorithm which adjusts the location of the model's surface nodes to a consistent predefined threshold Hounsfield unit value. Three cadaveric human femora specimens were CT scanned, and surface models were created after a semi-automatic segmentation by three different experienced operators. A FE analysis was conducted for each model, with and without applying the surface-adjustment algorithm (a total of 18 models), implementing identical boundary conditions. Maximum principal strain and stress and spatial coordinates were probed at six equivalent surface nodes from the six generated models for each of the three specimens at locations commonly utilised for experimental strain guage measurement validation. A Wilcoxon signed-ranks test was conducted to determine inter-operator variability and the impact of the PVEE-adjustment algorithm. The average inter-operator difference in stress values was significantly reduced after applying the adjustment algorithm (before: 3.32 +/- 4.35MPa, after: 1.47 +/- 1.77MPa, p=0.025). Strain values were found to be less sensitive to inter-operative variability (p=0.286). In summary, the new approach as presented in this study may provide a means to improve the repeatability of subject-specific FE models of bone obtained from CT data.