Three-dimensional modeling of the cochlea by use of an arc fitting approach

Abstract

Purpose: A cochlea modeling approach is presented allowing for a user defined degree of geometry simplification which automatically adjusts to the patient specific anatomy. Model generation can be performed in a straightforward manner due to error estimation prior to the actual generation, thus minimizing modeling time. Therefore, the presented technique is well suited for a wide range of applications including finite element analyses where geometrical simplifications are often inevitable. Methods: The method is presented for n=5 cochleae which were segmented using a custom software for increased accuracy. The linear basilar membrane cross sections are expanded to areas while the scalae contours are reconstructed by a predefined number of arc segments. Prior to model generation, geometrical errors are evaluated locally for each cross section as well as globally for the resulting models and their basal turn profiles. The final combination of all reconditioned features to a 3D volume is performed in Autodesk Inventor using the loft feature. Results: Due to the volume generation based on cubic splines, low errors could be achieved even for low numbers of arc segments and provided cross sections, both of which correspond to a strong degree of model simplification. Model generation could be performed in a time efficient manner. Conclusion: The proposed simplification method was proven to be well suited for the helical cochlea geometry. The generated output data can be imported into commercial software tools for various analyses representing a time efficient way to create cochlea models optimally suited for the desired task.

Keywords:

• Segmentation
• cochlea modeling
• geometry simplification
• CAD model generation

Notes

No potential conflict of interest was reported by the authors.

1 Note that numerically speaking, i.e. under the consideration of numerical errors, the angle between the two normal vectors must be lower than a predefined tolerance value. This value is significantly smaller than the segmentation angle . In the presented case with , the tolerance was set to .

Additional information

Funding

This work has been supported by the Deutsche Forschungsgemeinschaft (DFG) within the Cluster of Excellence Hearing4all.