Sexual dimorphism of foramen magnum using Cone Beam Computed Tomography

The aim of this study was to evaluate whether the foramen magnum (FM) dimensions could be used for sex determination using the Cone Beam Computed Tomography (CBCT).

Two hundred and sixty six CBCT full Field Of View (FOV) scans (111 males and 115 female subjects) of the skull were retrospectively selected and the FM length, width measured on reconstructed axial cross section by two observers using the CS 3D imaging software at a slice thickness of 300 μm and the FM area subsequently calculated using two established formulae by Routal and Teixeira. All data were subjected to descriptive and discriminant functional analysis to validate the expression of sexual dimorphism in the metric parameters of FM.

Using the FM dimensions the overall accuracy rate of sex determination was 66.4%. Out of these, 70.3% of males and 62.6% of females were sexed correctly. The best parameter for sex determination was the Area of the FM. In addition, the accuracy rate of sex prediction using the Area dimensions (Teixeira's formula) was 66.4%, same as that of all the four FM parameters used together.

This study validates that there is statistically significant expression of sexual differences in the foramen magnum region, which may prove useful and reliable in predicting sex in partial skull remains by discriminant function analysis when other methods tend to be inconclusive. It suggests the reliability, usability and accuracy of CBCT in forensic identification.