HIGH-RESOLUTION 3-D IMAGING OF MIDDLE EAR OSSICLES AND THEIR SOFT TISSUE STRUCTURES IN INTACT GERBIL TEMPORAL BONES, USING ORTHOGONAL FLUORESCENCE OPTICAL SECTIONING

Detailed models of middle ear morphology are an important input to improve realism of computer models of middle ear mechanics. Established imaging techniques all have their specific limitations. Orthogonal-plane fluorescence optical sectioning or OPFOS, is an important additional technique which, after adequate specimen preparation, produces high quality, perfectly aligned sectional images in nearly real-time of both bone and soft tissue simultaneously. The technique was introduced by A. Voie with a slicing resolution of 14 mu m. Using improved optical design and adding motorized scanning along a direction of the image plane, we were able to reduce slicing thickness to 2 m, thus creating a high-resolution OPFOS (HROPFOS) technique. Sections from HROPFOS data show histological detail, f.i. the hollow structure of the stapes head, cavities within the body of the ossicles, etc. From the section data, we reconstructed accurate 3-D models of the middle ear ossicles and its soft tissue structures, such as the stapedial muscle and artery which are nearly invisible with X-ray CT By imaging bone as well as soft tissue, these models are an important input for finite-element modeling. Measurements were obtained in preparations of intact temporal bones of gerbils, as the technique allows region-of-interest scanning.