Establishment And Evaluation Of Sex Determination Method From 12th Thoracic Vertebrae Based On Three-dimensional Reconstructed Models

Personal identification, which includes sex and race determination and age and stature estimation, is an important academic focus in fields such as forensic science, anthropology, archaeology, and so on. There are various difficulties in personal identification when it comes to actual forensic situations, such as in criminal cases the corpus would be in the high level corruption and mutilations; in disasters or accidents, many people died, the body has severely damaged and difficult to identify; in archaeological cases, only fragmented bones can be obtained; and so on. All such cases would cause obstacles in personal identification. Bones are most likely to be first-hand materials, for they are the easiest to be preserved in those special circumstances. The determination of the sex of the individual is the first essential step for positive identification as it decreases the possible matches by 50%. Sex determination from bones is an important academic focus of personal identification from bones in fields such as forensic science, anthropology, archaeology, and so on. The lower thoracic and lumbar vertebrae are often preserved well in archaeological skeletal assemblages and forensic contexts, because of their weight-bearing function and relative density, even when bone preservation is problematic for the axial skeleton, such as pelvic bone, skull and limbs. The objective of the study is to establish the method of using the 12th vertebra for sex determination of adult Chinese and evaluate its effect. The concrete methods are as follows: A total of 120 three-dimensional 12th thoracic (T12) vertebral models of Chinese subjects (60 males and 60 females) were obtained from the Department of Radiology, China-Japan Union Hospital of Jilin University. The 12th thoracic vertebra was developed by the clinic abdomen CT images. All images were retrieved on the CT workstation (advantage workstation 4.3, GE Medical System, General Electric Company, USA). The region of interest of the 12th vertebra was reformatted with 3D reconstruction. The 3D models of the 12th vertebra can be rotated, cut, clipped, and measured. A total of 25 linear measurements on 7 aspects of the vertebra were measured and 4 ratios were calculated. The items were selected which had the significant difference to establish the sex determination equation and was effect. The results show that of the total 29 traits, 27 were sexually dimorphic (P<0.05), the accuracy was 56.3%-89.2%, 8 traits had the accuracies mean or over 80.0%; the trait iVL had the highest accuracy of 89.2%. A function with four variables predicting sex with 90.8% accuracy was derived by using stepwise method of discriminant function analysis: Y=2.98×iBDsm+1.97×PH+3.37×BHp+3.27×sVL/BHa-32.80(mean centroids=-7.69). According to the study we can conclusion that the method of using the selected traits for sex determination of adult Chinese is practicable and has a relatively high accuracy.