Abstract:

Objective   To evaluate and analyze the accuracy and reliability of craniofacial landmark identification based on three-dimensional computerized tomography(CT) visualization images. Methods   Twenty CT images were randomly selected from the Department of Orthodontic, School of Stomatology, Shandong University. Nineteen common craniofacial landmarks were chosen in our study. Landmark coordinates for each image were obtained three times within one week by two investigators. Measurement error(ME) was used to assess the accuracy. Intra-class correlation coefficients(ICC) for all landmark coordinates were obtained to evaluate intra-observer and inter-observer reliabilities. Results   Intra-observer ME at X, Y and Z coordinate axes was 0.36, 0.30 and 0.25mm, respectively. Inter-observer ME at X, Y and Z coordinate axes was 0.78, 0.55 and 0.43mm, respectively. Intra-observer and inter-observer reliabilities of all coordinates for 70% of landmarks were greater than 0.9(ICC value). Conclusion   Craniofacial landmark identification based on three-dimensional images has a high accuracy and reliability for most landmarks. Intra-observer ME is less than interobserver ME. Landmarks with high intra-observer and inter-observer reliabilities should be chosen for three-dimensional image registration and measurement, which can decrease the ME.

Key words: Craniofacial landmarks; Three dimensional image; Accuracy;  Reliability