Computed tomography-based sex determination using osseous and pneumatic components of the temporal bone in a Japanese population

OBJECTIVES: The temporal bone, particularly its petrous portion, is highly dense and resilient, preserving its morphology under extreme conditions. This study aimed to three-dimensionally measure the volume of bone and air of the temporal bone using computed tomography (CT) and to develop an objective, high-accuracy sex estimation model for a contemporary Japanese population. METHODS: CT images of 120 Japanese adults (57 male, 63 female) were analyzed. Utilizing three-dimensional reconstructed images, the bone volume and air volume were measured. The predictive performance was assessed using classification accuracy and the area under the curve (AUC) from receiver operating characteristic (ROC) analysis. RESULTS: Descriptive statistics demonstrated significant sexual dimorphism in both bone volume and air volume across bilateral sides, with males exhibiting significantly larger values than females. In the binary logistic regression analysis, models incorporating specific morphometric parameters provided stable discriminant functions. CONCLUSIONS: Our findings indicate substantial sexual dimorphism in the temporal bone morphology of modern Japanese individuals. In particular, the logistic regression models combining the inner air cell pneumatization and the outer bone volume-both of which are highly resistant to postmortem changes-offer an objective and reliable method for sex estimation. This approach serves as a practical and useful screening tool in forensic practice and disaster victim identification (DVI) scenarios where the pelvis or other cranial structures are unavailable.