Evaluation of the accuracy and reliability of 3-dimensional computerized tomography for measurement of maxillofacial region

Song, Jae Chul; Jang, Hyun Jung; Lee, Sang Han

Abstract

The purpose of this study was to evaluate the reliability and accuracy of measurements obtained from 3-dimensional reconstructions of computerized tomography(CT) scans. The CT scans of six human dry skulls were 3-dimensional image reconstructed, and the cephalometric landmarks were recorded as X, Y, Z coordinates by two observers. Computerized cephalometrics were performed on the frontal and lateral cephalograms. Intraobserver and interobserver variations were calculated for each method and tested for statistical significance. And measurements taken from 3-dimensional CT were compared with corresponding manual measurements taken from the dry skulls. The results were as follow: 1. Intra-observer standard deviation of landmarks of the 3-dimensional CT by two observers were 0.49mm and 0.37mm in X axis, 0.26mm and 0.20mm in Y axis, and 0.29mm and 0.32mm in Z axis. There were highly significant, and large correlation between two observers(p<0.01). 2. Intra-observer standard deviation of landmarks of the frontal and lateral cephalogram by two observers were less than 1mm in all landmarks, but in the frontal cephalogram, standard deviation and range of right and left orbitale was larger than 3-dimensional CT about two times. There were highly significant, and large correlation between two observers(p<0.01) except for ROr in X axis of frontal cephalogram and Po of lateral cephalogram. 3. In comparison with manual measurements, 3-dimensional CT measurements increased 0.37mm and decreased 0.46mm in maximum and the mean difference between two methods was 0.29mm. There were highly significant, and large correlation between two methods(p<0.01). This study showed that landmarks recorded from 3-D CT reproduced very accuratly and there were little differences between 3-D CT and manual measurement. Therefore 3-D CT is very accurate and reliable method for measurement of maxillofacial region.