Reproducibility of osseous landmarks used for computed tomography based three-dimensional cephalometric analyses

SummaryPurposeThe aim of this paper was to measure the reproducibility of osseous landmark identification from two recently described three-dimensional (3D) cephalometric analyses: 3D-ACRO and 3D-Swennen analyses. The study population consisted of 13 patients examined with spiral 3D computed tomography (CT). We used a previously validated low-dose CT protocol. For each analysis, 22 cephalometric reference landmarks were identified on 3D CT surface renderings. Forty-four reference landmarks were identified per patient. Two series of identifications were performed by two independent observers. In total, 3432 imaging measurements were completed. The intra-observer reconstructed mean log was 1.210 ± 1.042 mm for the 3D-ACRO analysis, and 1.311 ± 1.042 mm for 3D-Swennen analysis (comparison: p = 0.17 NS). The inter-observer reconstructed mean log was 1.799 ± 1.037 mm for the 3D-ACRO analysis, and 2.465 ± 1.036 mm for 3D-Swennen analysis (comparison: p = 0.000000002). The difference between the intra- and inter-observer reconstructed mean logs were 1.486 ± 1.057 mm for 3D-ACRO and 1.880 ± 1.056 mm for 3D-Swennen analysis. In conclusions: 3D-ACRO analysis was significantly more reproducible than 3D-Swennen analysis (p = 0.0027) due to the use of a majority of highly reproducible cephalometric landmarks. Finally, we propose a classification scheme and exclusion criteria for reference landmarks used in 3D cephalometrics, based on inter-observer reproducibility and anatomical reality.