Evaluation of mastoid air cell system by three-dimensional reconstruction using sagittal tomography of the temporal bone.

The mastoid air cell system has been recognized as an important contributor to the pathophysiology of middle ear inflammatory diseases. Various methods of temporal bone imaging have been designed to investigate the correlation between middle ear disease and mastoid pneumatization. In this study, the mastoid air cell system was reconstructed three-dimensionally from sagittal tomographic images of the temporal bone on X-ray films, using a personal computer to evaluate the mastoid pneumatization in a total of 29 patients with chronic otitis media, adhesive otitis media, adhesive-type cholesteatoma, attic cholesteatoma and cholesterol granuloma, and in five normal subjects as controls. Reconstructed three-dimensional images of the mastoid air cell system and its volume were analyzed. The reconstructed images were helpful in recognizing the three-dimensional solid appearance of the mastoid air cell system. The volume of the reconstructed mastoid air cell system was significantly reduced compared with that in the controls in each of the patient groups. Mastoid pneumatization in the patients with adhesive-type cholesteatoma was significantly suppressed compared with that in the adhesive otitis media patients. Interestingly, the adhesive otitis media group showed cell development at the tip of mastoid process, whereas the group of adhesive-type cholesteatoma did not, suggesting a difference in the pathophysiology in the two diseases. We found that three-dimensional reconstruction of the temporal bone using sagittal tomographic images was useful in evaluating the state of mastoid air cell system development in individual cases and in investigating the pathophysiology in middle ear disease.