Accuracy of linear craniometric measurements obtained from laser scanning created 3D models of dry skulls

Abstract

The aim of this study was to establish the reliability of directly taken linear measurements on dry skulls and corresponding measurements taken on the 3D digital models created by laser scanning as well as to assess the agreement between both measuring methods. Four skulls were measured in two competitive methods—a direct measuring, based on the conventional craniometric method, and a digital measuring, accomplished on 3D models created by laser scanning. Thirteen cranial measurements were taken on both dry skulls and 3D models. The intraand inter-examiner reliability was estimated using intraclass correlation coefficient. The agreement between both measuring methods was assessed applying the Bland-Altman method for replicated measurements. A Bland-Altman plot was constructed for each of the 13 parameters. The 3D model and directly taken measurements were assessed as highly reliable and reproducible, excepting the orbital height. Our results showed that 96 % of all digital measurements differ from the directly taken ones with less than 2 mm and respectively 67.6 % differ with less than 1 mm. Based on the results of the Bland-Altman plots, most of the measurements obtained by both measuring methods could be accepted as comparable, since the majority of differences were within the constructed limits of agreement. However, there were digital measurements, particularly these with landmarks situated on bone margins, which systematically overestimated the directly taken ones.