Simulated Injuries of the Sheep Ossicular Chain: Correlations With Their Radiological Images.

Abstract

Hypothesis We hypothesized that a sheep temporal bone would be a suitable model to study correlations between simulated middle ear injuries and their radiological appearances. Simulated ossicular chain injuries correlate well with their radiological images, and post-processing techniques provide optimal visualization of the sheep ossicles. Background The subtle ossicular trauma may be difficult to assess due to the small size of the structures. The precise radiological and clinical correlations of the ossicular injuries are not well documented. Methods The most common traumatic ossicular chain injuries were systematically simulated in the sheep temporal bone model. The images of the temporal bones were obtained with a high-resolution computed tomography scanner. The values of the dislocations were measured from the obtained images as well as in the temporal bones using calipers. Two observers independently evaluated the fine structures of the auditory ossicles using oblique multiplanar reconstructions (MPRs) and maximum intensity projections (MIPs). All segments of the facial nerve were also visualized. Results Optimal visualization planes of the sheep's middle ear joints have been obtained. The coincidence of simulated ossicular injuries in the specimens and MIPs was 40%. All structures of the ossicular chain were clearly distinguished except for the stapes footplate. Evaluation of the traumatic changes of the incudostapedial joint was challenging. Conclusions The sheep temporal bone is a suitable model for studying the correlations between pathological alterations in the ossicular chain and their radiological appearances. The post-processing MIP technique provides a more accurate and easier diagnosis of traumatic ossicular chain injuries than MPRs alone.