The effect of in situ/in vitro three-dimensional quantitative computed tomography image voxel size on the finite element model of human vertebral cancellous bone

Abstract

Quantitative computed tomography-based finite element modeling technique is a promising clinical tool for the prediction of bone strength. However, quantitative computed tomography-based finite element models were created from image datasets with different image voxel sizes. The aim of this study was to investigate whether there is an influence of image voxel size on the finite element models. In all 12 thoracolumbar vertebrae were scanned prior to autopsy (in situ) using two different quantitative computed tomography scan protocols, which resulted in image datasets with two different voxel sizes (0.29 3 0.29 3 1.3 mm 3 vs 0.18 3 0.18 3 0.6 mm 3 ). Eight of them were scanned after autopsy (in vitro) and the datasets were reconstructed with two voxel sizes (0.32 3 0.32 3 0.6 mm 3 vs. 0.18 3 0.18 3 0.3 mm 3 ). Finite element models with cuboid volume of interest extracted from the vertebral cancellous part were created and inhomogeneous bilinear bone properties were defined. Axial compression was simulated. No effect of voxel size was detected on the apparent bone mineral density for both the in situ and in vitro cases. However, the apparent modulus and yield strength showed significant differences in the two voxel size group pairs (in situ and in vitro). In conclusion, the image voxel size may have to be considered when the finite element voxel modeling technique is used in clinical applications.

Effects of Scan Resolutions and Element Sizes on Bovine Vertebral Mechanical Parameters from Quantitative Computed Tomography-Based Finite Element Analysis

“…The correlations between predicted (PA and PB resolutions) and experimentally measured results were investigated in our study by developing the linear regression models, in which vertebral strength and stiffness estimated from the two resolution models were used as predictors of values obtained from the compressive mechanical tests. The errors of the exterior material property distributions of QCT/FEA models reconstructed from in vitro datasets are larger than those reconstructed from in situ datasets, which would consequently influence the apparent elastic modulus and yield strength predicted from FE models [24, 25]. In order to minimize this limitation and for the convenience to explore the effects of scan resolutions and element sizes on the QCT/FEA outcomes, FE model with cuboid VOI from the vertebral body center was used instead of a whole vertebral body model.…”

“…In-plane resolution, slice thickness, and the scan status of specimen (in situ/in vitro) influence image voxel size, which will affect subsequent prediction [24, 25]. Although a large number of studies have shown that QCT images with different quality will affect the results of FEA, but the relationship between scan resolution and element size needs further investigation.…”

Image-based biomechanical models of the musculoskeletal system

“…Since voxel size was shown to impact the accuracy of FEA results [61], high-resolution imaging has the potential to markedly improve the quality of the predictions. HR-QCT have been used to perform 3D measurements of the peripheral skeleton (typically radius and tibia) to get information about volumetric BMD, cortical/trabecular geometry, and ultimately on bone quality.…”

MRI-based assessment of proximal femur strength compared to mechanical testing

“…First, CT scans produce ionizing radiation which have known health risks. Moreover, the accuracy of finite element models may depend upon imaging resolution [16,[30][31][32][33], and the resolution of CT scans is proportional to the amount of radiation it produces. Since the pelvic region is especially radiosensitive, due to bowels and pelvic organs, clinical CT scans of the hip are typically limited to 1mm voxels, which prohibits accurate characterization of bone microstructure.…”