Computed tomography of the occipital bone for sex estimation in Turks

Sex estimation is a fundamental component of forensic identification when DNA analysis is not feasible. Because cranial morphology and sexual dimorphism vary among populations, population-specific standards are required. However, occipital bone morphometric data for Turkish adults remain limited. Therefore, the aim of this study was to evaluate the reliability of occipital bone measurements obtained from cranial computed tomography for sex estimation in Turkish adults.

Three-dimensional cranial computed tomography images of 384 individuals (192 females, 192 males), aged 18-65, obtained between 01/01/2010 and 31/12/2021, were retrospectively analyzed. Nine anatomical distances on the occipital bone were measured, and their discriminative roles in sex estimation were assessed using logistic regression analysis. Additionally, inter-observer agreement was evaluated by comparing measurements from two independent observers.

The combined analysis of all measurements yielded a sex prediction accuracy of 82.8% for females and 80.2% for males. Foramen magnum width, occipital condyle length, occipital condyle width, and external occipital protuberance depth were identified as the most discriminative variables. A model combining these four variables achieved classification accuracies of 83.3% for females and 79.2% for males, with an overall accuracy of 81.3%. The full model including all nine measurements showed an overall accuracy of 81.5%. High intra- and inter-observer agreement was observed.

Computed tomography-based morphometric analysis of the occipital bone is a reliable method for sex estimation in forensic medicine. These results support the development of population-specific reference data for the Turkish population.