The Reconstruction And Validation Of The Human External Acoustic Meatus And Middle Ear Finite Element Model

Aim:In this research, a fresh temporal bone specimen of human and Micro-Computer Tomography was used and a whole set of the tomography of the human ear was obtained except the auricle. Based on the accurate tomography, the geometric model, the mesh model and the finite element model was reconstructed, and the finite element model be validated. Normal and morbid structures of outer ear, middle ear and inner ear can be simulated by the finite element model. Across the simulation process, the characters of the sound transduction could be found and the possible remediation maybe emerge, that would provided theoretical basis for modification of the clinical operation.Method:A freshly cadaveric head (male, age 45), obtained through the Anatomy Research Department of Shanghai Medical school of Fudan University and visually inspected using an ear endoscope to confirm an intact eardrum and normal external acoustic meatus, was dissected and two temporal bones were achieved. The left one was used in this study. Then the specimen was trimmed under an operative microscope, using an ontological electronic drill. This procedure was done to make sure the specimen with intact external acoustic meatus and middle ear system and inner ear system, and could stably erect along with its longitudinal axis in a Micro-Computer Tomography scan bin. Make sure the entrance of the external acoustic meatus adown and run the high resolution scanning. After that, base on the three dimensional volume data, two stacks of serial images were generated in the resolution 13*13micrometer/pixel and 45*45 micrometer/pixel, all the images were saved in DICOM format. The images were imported into MIMIC, in order to achieve the best resolving effect a suitable windows level and width was selected, and were check the continuously of all components in three orientation and a suitable direction was selected to generated a new serial images. The images were edited in PHOTOSHOP, and imported into reverse engineering software for three dimensional reconstructions, all structures were reconstructed separately with one global coordinate system, some structures optimization and partition was done in this software. Then the geometric models were imported into preprocess software to generate the assemble and the mesh model, some materials and property were defined and assigned to those elements, some boundary conditions and loads were defined also. The final finite element was imported into the finite element analysis software to check its validity and feasibility through compare with the literature experiment data.Result:The images were generated by the Micro-CT with high-quality and all structures could be indentified continuously in the whole set of images. Two set of images could be used for the reconstruction, the second set was used in this research. A finite element model of human ear was constructed and the simulated results were compatible with the literature findings. Due to the extremely complex of the inner ear and inexperience in the pre-process for the specimen, the most structures of the membranous labyrinth system cannot be recognized continuously even in the 13*13micrometer/pixel data set.Conclusion:The finite element model with its height optimization and its simulation compatible with the literature findings, confirm the feasibility of this offered method to reconstruct a finite element model of human ear, this validated model could be used for the preclinical research for the outer ear and middle ear pathological changes. However, human ear is an entire system, the research for the inner ear reconstruction is necessary.