Computer Aided Design for Three-Dimensional Visualization and Modeling of Middle Ear Biomechanics

Abstract

Objectives: The aim of the study was to present a systematic and practical approach that used high-resolution computed tomography (HRCT) to derive models of the middle ear for finite element analysis. Material and Methods: This prospective study included 48 patients with cholestetoma. Temporal bone images obtained from 25 right ears and 23 left ears were used for evaluation and reconstruction. The normal ears were used for image reconstruction. HRCT of the temporal bone was performed using simultaneous acquisition of 16 sections with a collimated slice thickness of 0.625 mm. All images were transferred to an amira visualization system for 3D reconstruction. The created 3D model was translated into two commercial modeling packages, Patran and ANSYS, for finite element analysis. The characteristic dimensions of the model were measured and compared with previously published histological section data. Results: The results confirmed that the geometric model created by the proposed method is accurate, with the exception that the tympanic membrane is thicker than that of the histological section method. No obvious difference in geometrical dimensions between right and left ossicles was found (p＞0.05). The 3D model created by the finite element method and predicted umbo and stapes displacements are close to the bounds of the experimental curves of Nishihara's, Huber's and Gan's data across the frequency range of 100-8000 Hz. Conclusions: The model includes a description of the geometry of the middle ear components and dynamic equations of vibration. The proposed method is quick, practical, low-cost and, most importantly, noninvasive compared with histological section methods.