HYPERELASTIC WARPING APPLIED TO X-RAY MICRO-CT IMAGES FOR THE STUDY OF HUMAN MIDDLE EAR CHAIN DEFORMATIONS UNDER STATIC PRESSURE LOAD

In everyday life the human ear is subject not only to sound but also to slow, quasi-static pressure variations with amplitudes in the order of tenths of a mm. In the present study we investigated how the ossicular chain deforms and changes its 3-D configuration when acted upon by large static pressures. To determine with good precision the small deformations of the ossicular chain we use ‘hyperelastic warping’, a deformable image registration method. In this relatively new technique a 3-D finite element model, based on careful segmentation of a template dataset, is deformed until it aligns with a target dataset at a different pressure. 3-D displacement of the ossicles will be shown and expressed mathematically by plotting the displacement of a few landmark points as a function of pressure. We will also describe the 3-D changes in configuration and show how the slippage in the ossicle joints performs as a protecting mechanism of the middle ear.