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This study revealed the usefulness of volumetric analysis of mastoid air cells (MACs) extracted from postmortem computed tomography (PMCT) images in characterizing individuals. To characterize deceased persons, the MACs volumes of 61 Japanese PMCT images were measured after thresholding in Hounsfield units and based on the number of voxels on the right and left sides and the voxel size for each person. The volume differences between the right and left MACs and sex were examined. Although there were no obvious volume differences between males and females, the order of sizes on the two sides varied for each person. Moreover, deceased persons could be roughly classified using the total volume of MACs. Deceased persons with similar total volumes could be distinguished further by comparing the ratio of volumes in bilateral MACs. Although the identification process is dependent on samples and different sizes of bilateral MACs, our pilot study indicated that 81.9% (50/61) of deceased persons could be distinguished. In conclusion, volumetric analysis of MACs measured using PMCT imaging has the potential to identify individuals and reduce the number of candidates.

This study revealed the usefulness of volumetric analysis of mastoid air cells (MACs) extracted from postmortem computed tomography (PMCT) images in characterizing individuals. To characterize deceased persons, the MACs volumes of 61 Japanese PMCT images were measured after thresholding in Hounsfield units and based on the number of voxels on the right and left sides and the voxel size for each person. The volume differences between the right and left MACs and sex were examined. Although there were no obvious volume differences between males and females, the order of sizes on the two sides varied for each person. Moreover, deceased persons could be roughly classified using the total volume of MACs. Deceased persons with similar total volumes could be distinguished further by comparing the ratio of volumes in bilateral MACs. Although the identification process is dependent on samples and different sizes of bilateral MACs, our pilot study indicated that 81.9% (50/61) of deceased persons could be distinguished. In conclusion, volumetric analysis of MACs measured using PMCT imaging has the potential to identify individuals and reduce the number of candidates.

Purpose: This was a preliminary study to assess surgical construction and regeneration of mastoid air cells in the treatment of cholesteatoma. Methods: Two-stage tympanoplasty with mastoidectomy was performed in four cases of unilateral cholesteatoma with sclerotic mastoid. During the first-stage operation, small fragments of autologous cortical bone were inserted into the cavity after mastoidectomy to form a honeycomb-like structure. Reconstruction of the lateral wall of the mastoid cavity was performed using the mastoid cortical bony plate. Pre- and postoperative mastoid volume was evaluated by three-dimensional reconstruction based on high-resolution computed tomography (HR-CT) images. Results: HR-CT images after the first-stage operation showed that mastoid volume had increased in all subjects. Macroscopic inspection during the second-stage operation revealed that the honeycomb-like structure made of bony fragments and covered by thin mucosa in the mastoid cavity was stable, with no evidence of effusion or granulation tissue. No retraction of the eardrum, middle ear effusion or recurrence of cholesteatoma was observed, and the hearing level on a pure-tone audiogram was improved in any subject 60 - 94 months after the second-stage operation. Conclusion: Surgical construction and regeneration of mastoid air cells using autologous cortical bone can be useful in treatment of cholesteatoma with arrested mastoid pneumatization., Surgical Science, 3(11), pp.514-517; 2012