Abstract
Purpose
Age-matched average 3D models facilitate both surgical planning and intraoperative guidance of cranial birth defects such as craniosynostosis. We aimed to develop an algorithm that accepts any number of CT scans as input and generates highly accurate, average models with minimal user input that are ready for 3D printing and clinical use.
Methods
Using a compiled database of ‘normal’ pediatric computed tomography (CT) scans, we report Normscan, an open-source platform built in Python that allows users to generate normative models of CT scans through user-defined landmarks. We use the basion, nasion, and left and right porions as anatomical landmarks for initial correspondence and then register the models using the iterative closest points algorithm before downstream averaging.
Results
Normscan is fast and easy to use via our user interface and also creates highly accurate average models of any number of input models. Additionally, it is highly repeatable, with coefficients of variance for the surface area and volume of the average model being less than 3% across ten independent trials. Average models can then be 3D printed and/or visualized in augmented reality.
Conclusions
Normscan provides an end-to-end pipeline for the creation of average models of skulls. These models can be used for the generation of databases of specific demographic anatomical models as well as for intraoperative guidance and surgical planning. While Normscan was designed for craniosynostosis repair, due to the modular nature of the algorithm, Normscan has many applications in other areas of surgical planning and research.
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Acknowledgements
We gratefully acknowledge Robert Finedor for thoughtful discussions on techniques to optimize the algorithm. We also thank the Alkureishi lab for their support, thoughtful academic guidance on this project, and for creating a wonderful working environment.
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GRN and LA designed the study; GRN performed the experiments and analyzed the data; MAM and NBZ performed statistical analysis, LA supervised the experiments; GRN, NBZ, and LA wrote the manuscript.
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This work was presented as a poster at the The Midwest Association of Plastic Surgeons 61st Annual Meeting in July 2023 in Lake Geneva, WI.
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Nahass, G.R., Marques, M.A., Bou Zeid, N. et al. Normscan: open-source Python software to create average models from CT scans. Int J CARS (2024). https://doi.org/10.1007/s11548-024-03185-0
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DOI: https://doi.org/10.1007/s11548-024-03185-0