Lippold Carsten, Liu Xiang, Wangdo Kim, Drerup Burkhard, Schreiber Kristina, Kirschneck Christian, Moiseenko Tatjana, Danesh Gholamreza
Department of Orthodontics, University Medical Centre of Muenster, Waldeyerstraße 30, 48149 Münster, Germany.
Head Face Med. 2014 Dec 8;10:54. doi: 10.1186/1746-160X-10-54.
Three-dimensional landmarks of the face are important for orthodontic examination, harmony assessment and treatment planning. Currently, facial landmarks are often measured by orthodontists via direct observation and manual soft tissue image analysis. This study wants to evaluate and present an objective method for measuring selected facial landmarks based on an analysis of curvature maps and of sagittal profile obtained by a laser-scanning method.
The faces of 15 people were scanned in 3D by means of the laser scanner FastSCAN™. It allowed the recording of a curvature map of the face in under a minute, which depicted the distribution of Gaussian and mean curvatures. The median-sagittal profile line of the face was localized in this map, and a mathematical analysis comprising its first and second derivatives was performed. Anatomical landmarks were identified and facial measurements performed. To assess validity the obtained data were compared with manual measurements by orthodontists by means of Lin's concordance correlation CCC coefficient and reliability was determined by consecutive measurements.
Facial landmarks, such as the soft tissue glabella and nasal tip, could be easily and accurately identified and located. Lin's CCC showed substantial agreement between digital and manual measurements for 4 of the 7 distances evaluated. Larger discrepancies were due to inadequate image quality and scanning errors. Reliability of consecutive measurements by the same operator was excellent.
In our pilot study the three-dimensional laser-scanning method FastSCAN™ allowed a reliable and accurate identification of anatomical landmarks of the face. The obtained distances between certain landmarks, such as the intercanthal distance, were largely consistent with those from manual measurements. Due to its easy and rapid implementation, the method facilitates facial analysis and could be a clinically valid alternative to manual measurements, when remaining problems in scanning accuracy can be resolved.
面部的三维标志点对于正畸检查、和谐性评估及治疗计划至关重要。目前，正畸医生常通过直接观察和手动软组织图像分析来测量面部标志点。本研究旨在基于对曲率图和通过激光扫描法获得的矢状面轮廓的分析，评估并提出一种测量选定面部标志点的客观方法。
使用FastSCAN™激光扫描仪对15人的面部进行三维扫描。该扫描仪能在一分钟内记录面部的曲率图，描绘高斯曲率和平均曲率的分布。在该图中定位面部的正中矢状轮廓线，并对其进行包含一阶和二阶导数的数学分析。识别解剖标志点并进行面部测量。为评估有效性，通过林氏一致性相关系数CCC将所得数据与正畸医生的手动测量结果进行比较，并通过连续测量确定可靠性。
诸如软组织眉间点和鼻尖等面部标志点能够轻松且准确地被识别和定位。林氏CCC显示，在所评估的7个距离中的4个，数字测量和手动测量之间存在高度一致性。较大差异归因于图像质量不足和扫描误差。同一操作员连续测量的可靠性极佳。
在我们的初步研究中，三维激光扫描方法FastSCAN™能够可靠且准确地识别面部的解剖标志点。某些标志点之间获得的距离，如内眦间距，与手动测量结果基本一致。由于其实施简便快捷，该方法便于面部分析，并且在扫描精度方面的遗留问题得以解决时，可能成为手动测量在临床上有效的替代方法。
