Reproducibility and reliability of three-dimensional soft tissue landmark identification using three-dimensional stereophotogrammetry.

OBJECTIVE To evaluate the intraexaminer repeatability and interexaminer reproducibility of soft tissue landmarks on three-dimensional (3-D) stereophogrammetric images. MATERIALS AND METHODS Thirty-four stereophotogrammetric images were taken and 19 soft tissue points were identified. The images were obtained using the 3-DMD Face (3-DMD TM Ltd, Atlanta, Ga) system. Two examiners marked 34 images manually with a mouse-driven cursor 4 weeks apart. Intraexaminer marking differences were calculated and classified as <0.5 mm, 0.5-1 mm, and >1 mm. Intraclass correlation coefficients were calculated for intraexaminer reliability. A paired-samples t-test was used to evaluate the difference between the examiners. Interexaminer reproducibility was evaluated by kappa analysis. Statistical significance was set at P < .05. RESULTS Only one landmark (labiale superior) had an intraexaminer marking difference less than 0.5 mm. Existing landmarks had an intraexaminer difference less than 1 mm, but higher than 0.5 mm. The intraclass correlation coefficients (ICCs) indicated good intraexaminer repeatability for both observers. The ICC range for examiners 1 and 2 was 0.986-1.000 and 0.990-1.000, respectively. Kappa scores showed good interexaminer agreement, especially on the z-axis. CONCLUSIONS Except labiale superior, the soft tissue landmarks used in this study were shown to have moderate reproducibility, but the difference between the landmarks was less than 1 mm, and they had clinically acceptable reproducibility.