Deriving intervertebral disc FEM models from MRI image segmentation in large cohorts

Abstract

Due to limited MRI resolution, patient-specific simulation models derived from medical images often lack bio-fidelity. To address this, we present a smoothing pipeline for generating high-fidelity meshes of vertebrae and intervertebral discs from medical images, which serve as a base for biomechanical simulations. Using a diverse array of vertebrae smoothing algorithms, including Laplace, HC Laplace, Taubin, and Two Step, alongside surface subdivision methods such as Tri-to-Quad by 4-8, Loop, LS3-Loop, Catmull-Clark, and Butterfly, we systematically explored 136 combinations across six protocols to determine an optimal smoothing pipeline. Subsequently, an adaptive smoothing algorithm was developed for intervertebral disc meshes. By adjusting intervertebral disc vertex locations to those of the vertebra mesh, we ensured seamless alignment of contact surfaces including shared nodes. Evaluation of our pipeline against conventional smoothing methods demonstrates superior edge preservation and reduced stair-step effects, enhancing the fidelity of the generated meshes. Finite Element Method simulations further confirmed the accuracy of our selective smoothing pipeline, showing increased notch stress. Our pipeline, validated on a diverse dataset, offers an automated solution for generating patient-specific vertebrae and intervertebral disc models with enhanced biomechanical fidelity, enabling comprehensive studies in large cohorts and deeper insights into spine biomechanics and pathology.

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