Sex determination and age estimation method using the trabecular structure of the third cervical vertebral body by head and neck CT in Japanese adults.

Objectives: This study aimed to develop sex determination and age estimation equations using the trabecular structure of the third cervical vertebra from head and neck computed tomography (CT) images by analyzing bone microarchitecture.

Methods: Trabecular bone structure was analyzed in a centrally located region of interest (ROI) within the third cervical vertebral body (C3) using CT scans from 132 Japanese adults (66 males and 66 females). Three primary measurements were taken: total vertebral volume (Tissue Volume, TV; mm), trabecular bone volume (Bone Volume, BV; mm), and trabecular bone surface area (Bone Surface, BS; mm). Bone volume fraction (BV/TV; %) was calculated as a bone density index. Additional parameters-bone surface-to-volume ratio (BS/TV; mm/mm), bone surface-to-bone volume ratio (BS/BV; mm/mm), trabecular thickness (Tb.Th; μm), and trabecular number (Tb.N; 1/mm)-were measured. Sex differences were evaluated, and a logistic regression model was developed for sex determination. Age estimation equations were created for the total sample and by sex.

Results: Males had larger TV, BV, and BS than females. The sex determination model achieved 80.0 % accuracy. BV/TV declined with age, especially in females, while TV showed an increasing trend in males. Age estimation was more accurate for females (mean absolute error [MAE]: 11.67 years) than that for males (MAE: 14.15 years). Sex-related differences reflect skeletal variation and suggest menopause-associated bone loss may explain female model performance.

Conclusions: C3 trabecular structure offers forensic potential for both sex and age prediction. The developed models may contribute to individual identification by providing biologically meaningful estimations.