[Quantitative analysis of craniofacial skeleton asymmetry by three-dimensional computed tomography].

Objective To present a method of quantitative diagnosis of craniofacial skeleton deformities based on three-dimensional computed tomography (3D CT).Methods 20 cases with facial asymmetric deformities underwent 3D CT and the 3D images were reconstructed by Mimics 10.0 (Belgium).Anatomical landmarks were located and the coordinate of the landmarks obtained.Axial images of 1 patient with Romberg disease was used as representative case.The differences in the distance between the right landmarks and the left were calculated and analyzed.Results The measurement results were not significantly different between two stages with an interval of 4 weeks (P ＞ 0.05),showing a reproducible resutls.The deviation of landmarks at facial midline increased gradually from upward to downward,reaching (2.63 ± 0.54) mm at menton point.Paired landmarks showed asymmetry in three dimensions,especially gonion point on the left side,which was deviated 10.21 mm inward,9.26 mm fo.rward,6.30 mm upward,compared to the opposite side.Conclusions The method of 3D CT quantitative analysis can provide precise information in the diagnosis and treatment planning of facial asymmetry deformity. Key words: Imaging, three-dimensional ;  Tomography, spiral computed ;  Craniomaxillofacial surgery