Sinzinger F, van Kerkvoorde J, Pahr DH, Moreno R. Predicting the trabecular bone apparent stiffness tensor with spherical convolutional neural networks.
Bone Rep 2022;
16:101179. [PMID:
35309107 PMCID:
PMC8927924 DOI:
10.1016/j.bonr.2022.101179]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/15/2022] [Accepted: 03/03/2022] [Indexed: 12/14/2022] Open
Abstract
The apparent stiffness tensor is relevant for characterizing trabecular bone quality. Previous studies have used morphology-stiffness relationships for estimating the apparent stiffness tensor. In this paper, we propose to train spherical convolutional neural networks (SphCNNs) to estimate this tensor. Information of the edges, trabecular thickness, and spacing are summarized in functions on the unitary sphere used as inputs for the SphCNNs. The concomitant dimensionality reduction makes it possible to train neural networks on relatively small datasets. The predicted tensors were compared to the stiffness tensors computed by using the micro-finite element method (μFE), which was considered as the gold standard, and models based on fourth-order fabric tensors. Combining edges and trabecular thickness yields significant improvements in the accuracy compared to the methods based on fourth-order fabric tensors. From the results, SphCNNs are promising for replacing the more expensive μFE stiffness estimations.
Characteristic stiffness tensors are derived from trabecular bone micro-CT samples.
Previous approximation methods fall short on heterogeneous data-sets.
The gradient, trabecular thickness and spacing are mapped to a spherical domain.
Spherical convolutional neural networks are used for the prediction.
The prediction error is significantly reduced compared to the state-of-the-art.
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