Observer reliability of three-dimensional cephalometric landmark identification on cone-beam computerized tomography

Abstract

Objective-To evaluate reliability in 3D landmark identification using Cone-Beam CT.Study Design-Twelve pre-surgery CBCTs were randomly selected from 159 orthognathic surgery patients. Three observers independently repeated three times the identification of 30 landmarks in the sagittal, coronal, and axial slices. A mixed effects ANOVA model estimated the Intraclass Correlations (ICC) and assessed systematic bias.Results-The ICC was >0.9 for 86% of intra-observer assessments and 66% of inter-observer assessments. Only 1% of intra-observer and 3% of inter-observer coefficients were <0.45. The systematic difference among observers was greater in X and Z than in Y dimensions, but the maximum mean difference was quite small. Conclusion-Overall, the intra-and inter-observer reliability was excellent. 3D landmark identification using CBCT can offer consistent and reproducible data, if a protocol for operator training and calibration is followed. This is particularly important for landmarks not easily specified in all three planes of space.Three-dimensional cephalometry has long been proposed as the ideal for orthodontic diagnosis, treatment planning, and follow-up of the patients. 1 Diagnosis, treatment planning, and assessment of change over time have been routinely based on landmark based analysis in 2D cephalometry. 1 CORRESPONDING AUTHOR: Lucia H.S. Cevidanes, DDS, MS, PhD, UNC School of Dentistry, Assistant Professor, Department of Orthodontics, 201 Brauer Hall, UNC School of Dentistry, Chapel Hill, NC, 27599-7450, Phone: (919) 3578603, Email: cevidanl@dentistry.unc.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The use of Cone-Beam CT (CBCT) in dentistry offers great potential for 3D diagnosis and treatment planning compared to CT. 5-16 However, the development of three-dimensional landmark-based cephalometric analysis requires definition of 3D landmarks on complex curving structures, which is not a trivial problem. As Bookstein 16 noted, there is a lack of literature about suitable operational definitions for the landmarks in the 3 planes of space (coronal, sagittal, and axial). Practical considerations of identification errors, coupled with an essential need for biological relevance and a balanced representation of components of the craniofacial form, limit the number and nature of landmarks available for analysis. Historically landmarks, such as Articulare, were used because of the ease in landmark location on the 2D cephalometric projections, but these projected superimposed structures do not exist in the actual 3D facial structure. For these reasons, the...

Agreement of Dental Students in the Detection of Normal Landmarks When Comparing Digital Lateral Cephalograms and Three-Dimensional Cone Beam Computed Tomography Images

“…Two bilateral landmarks, i.e. the right and left ramus in the Y-coordinate and in the right and left Con in the Z-coordinate, showed low ICC scores (25). In our study, no ICC < 0.45 was reported.…”

“…3D as compared to 2D is important. de Oliveira et al (25) have evaluated the reliability of observers in 3D-landmark identification using CBCT. They showed that 3% of IRCs were < 0.45.…”

Reliability of a method to conduct upper airway analysis in cone-beam computed tomography

“…Before starting the analysis, each patient's head position was corrected with the Dolphin software tools, using the midsagittal, the Frankfort horizontal and the transporionic 15,16 planes as references, considering that small deviations in the position of the head are bound to exist.…”

Asymmetry assessment using cone beam CT

“…In these cases observers tend to locate the landmarks in the planes of easiest visualization. 9,10 Difficulty is created by inclusion of the medio-lateral dimension to landmark location, a dimension which was not considered when lateral cephalometric landmarks were created. 10 A benefit of CBCT landmark identification is a lack of superimposed structures, which creates easier visualization of certain skull regions.…”

“…Voxel size, type of image detector, scanning time, reconstruction time, radiation dose, and head position have been mentioned as variables that could affect CBCT linear measurements. 9,15 Two previous studies have investigated the effect of head position on linear measurements and found it insignificant. 16,17 Another study compared measurement accuracy using two different voxel settings with no difference in accuracy between the two groups.…”