3-DIMENSIONAL IMAGING AND OSTEOMETRY OF ADULT HUMAN SKULLS USING HELICAL COMPUTED-TOMOGRAPHY

To make a digital image database of human craniology, we optimized the three-dimensional (3-D) images of 29 dried human skull specimens by h elical computed tomography (CT). For the verification of the quantitat ive exactitude of these image data, we manually measured nine items of direct distances between standard anthropologic points on each skull and the corresponding distances projected on the CT monitor by specify ing the respective points. The results obtained by the two methods of manual and CT measurements were compared and statistically analyzed. T he CT measurements were so exact that the lower limit of correlation c oefficients (95% of the confidence interval) between the two results w as more than 0.8 in six items; i.e., maximal cranial length and breadt h, minimal frontal breadth, bizygomatic breadth, distance between ecto molares and nasion-basion length. In contrast, the CT results were les s well correlated with the manual measurements of three items; i.e., d istance between bilateral mastoidales, total facial height, and nasal breadth. We concluded that the qualitative representation of 3-D CT im ages was adequate, although some quantitative data may be incorrect. T he inaccuracy is suspected to be due to the difficulty in specifying t he standard points on the CT images, and due to the differences in mea surement procedures between the direct and projected distances.