The 3dMD photogrammetric photo system in cranio-maxillofacial surgery: Validation of interexaminer variations and perceptions

Background: Three-dimensional photography of the face is increasingly used to overcome the downsides of conventional photography or anthropometry regarding reliable evaluation. However, the precision of such a system has to be validated before it can be implemented for clinical use.

Material and methods: Eight people were photographed with the 3dMDface system using lighting from sets of 2 × 4 compact fluorescent lights in a clinical photography room without natural light sources. Two different operators then individually, and without interaction, marked 27 different anatomical landmarks using the 3dMD Patient software. During this process, the operators were fully blinded against each other. The purpose of the study was to determine the repeatability and accuracy of the system when used by different operators and at different times. The 3D differentiation was analyzed using mixed ANOVA with person as the random factor, and operator, repetition, and landmark as the fixed factors. The ANOVA was followed by a Ryan-Einot-Gabriel-Welsch F post-hoc test for landmarks.

Results: Statistical analysis grouped the landmarks into three subgroups: high precision, medium precision and low precision.

Conclusions: Virtual 3D models derived from the 3dMDface system not only provide a high level of technical precision but also of intra- and interobserver reliability regarding landmark identification. However, some of the classical landmarks are not reliable when it comes to virtual models; these are generally landmarks that examiners of real patients would tend to identify using palpation of underlying bony structures, such as the soft gonion.