In order to improve realism in middle ear (ME) finite-element modeling (FEM), comprehensive and precise morphological data
are needed. To date, micro-scale X-ray computed tomography (μCT) recordings have been used as geometric input data for FEM
models of the ME ossicles. Previously, attempts were made to obtain these data on ME soft tissue structures as well. However,
due to low X-ray absorption of soft tissue, quality of these images is limited. Another popular approach is using histological
sections as data for 3D models, delivering high in-plane resolution for the sections, but the technique is destructive in
nature and registration of the sections is difficult. We combine data from high-resolution μCT recordings with data from high-resolution
orthogonal-plane fluorescence optical-sectioning microscopy (OPFOS), both obtained on the same gerbil specimen. State-of-the-art
μCT delivers high-resolution data on the 3D shape of ossicles and other ME bony structures, while the OPFOS setup generates
data of unprecedented quality both on bone and soft tissue ME structures. Each of these techniques is tomographic and non-destructive
and delivers sets of automatically aligned virtual sections. The datasets coming from different techniques need to be registered
with respect to each other. By combining both datasets, we obtain a complete high-resolution morphological model of all functional
components in the gerbil ME. The resulting 3D model can be readily imported in FEM software and is made freely available to
the research community. In this paper, we discuss the methods used, present the resulting merged model, and discuss the morphological
properties of the soft tissue structures, such as muscles and ligaments.
Keywords gerbil – middle ear – modeling – high resolution – three-dimensional – soft tissue – surface mesh – micro-scale X-ray computed tomography (micro-CT) – orthogonal-plane fluorescence optical-sectioning microscopy (OPFOS)