喉气管狭窄三维有限元模型的构建及意义

Construction and significance of three-dimensional finite element model for laryngotracheal stenosis

摘要:

目的：为客观量化喉气管狭窄（LTS）所致气道结构的变化对气道流场、应力的影响，基于CT图像构建LTS三维有限元模型（3D FEM）。 方法：回顾性分析2022年06月至2024年06月收入我院耳鼻咽喉头颈外科，经手术确诊的LTS患儿，筛选出对应Cotton I度、II度、III度的LTS患儿3例和健康对照甲状舌管囊肿患儿1例，收集患儿喉镜、CT和病史资料。CT扫描所得到的DICOM图像导入MIMICS中，利用不同组织结构的材料灰度阈值差异进行区分，进行三维几何模型重建。通过HYPERMESH软件划分有限元网格，将几何模型转换为相应包含节点和单元的喉气管腔3D FEM。 结果：本文利用有限元技术，通过计算机辅助设计（CAD）和计算机辅助工程（CAE）软件建立了可反映儿童喉气管结构形态特征的3D FEM。正常组1894358个网格与LTS模型1559357个网格的配置方案，能够在保证计算效率的前提下满足湍流流场模拟的精度要求。这3个LTS模型对应的狭窄程度分别为30%，60%，90%，同时构建正常对照组（甲舌）模型，通过临床医师的辨认与比较，该模型同喉镜检查结果一致性良好。 结论：LTS 3D FEM结构清晰、形态逼真，准确反映了喉气管复杂的解剖结构关系，为后续气道计算流体力学（CFD）与流固耦合（FSI）数值模拟，奠定了基础。

Abstract:

Objectives: To objectively quantify the impact of airway structural changes caused by laryngotracheal stenosis (LTS) on flow field and stress, a three-dimensional finite element model (3D FEM) of LTS was constructed based on CT images. Methods: A retrospective analysis was conducted on children with LTS who were admitted to our hospital''s Department of Otolaryngology and Head and Neck Surgery from June 2022 to June 2024 and were diagnosed with LTS through surgery. Three children with LTS corresponding to Cotton I, II, and III degrees, and one healthy control child with a thyroglossal duct cyst were selected. Laryngoscopy, CT, and medical history data of the children were collected. The DICOM images obtained from CT scans were imported into MIMICS, and different tissue structures were differentiated using material grayscale threshold differences for 3D geometric model reconstruction. The finite element mesh was generated using HYPERMESH software, and the geometric model was converted into a 3D FEM of the laryngotracheal cavity containing nodes and elements. Results: This article utilizes finite element technology to establish a 3D FEM that reflects the structural and morphological characteristics of the larynx and trachea in children through computer-aided design (CAD) and computer-aided engineering (CAE) software. The configuration scheme of 1,894,358 meshes in the normal group and 1,559,357 meshes in the LTS model can meet the accuracy requirements for turbulence flow field simulation while ensuring computational efficiency. These three LTS models correspond to stenosis degrees of 30%, 60%, and 90%, respectively. A normal control group (thyroglossal) model was also constructed. Through identification and comparison by clinicians, this model showed good consistency with laryngoscopy results. Conclusions: The LTS 3D FEM structure is clear and realistic in morphology, accurately reflecting the complex anatomical structure relationships of the larynx and trachea. This lays a foundation for subsequent computational fluid dynamics and fluid-structure interaction numerical simulations of the airway.