Toma A M, Zhurov A, Playle R, Ong E, Richmond S
Department of Applied Clinical Research & Public Health (Orthodontic Department), Cardiff University Dental Hospital, Heath Park, Cardiff, CF14 4XY, Wales, UK.
Orthod Craniofac Res. 2009 Feb;12(1):33-42. doi: 10.1111/j.1601-6343.2008.01435.x.
The three-dimensional (3D) measuring technology is useful to inspect facial shape in three planes of space (X, Y, and Z). Recent work has been directed to analyse craniofacial morphology using facial soft tissue landmarks to identify facial differences among population. The reproducibility of facial landmarks is almost necessary to ensure accurate 3D facial measurements.
The aim of this study is to assess the reproducibility of facial soft tissue landmarks using laser-scan 3D imaging technology.
Facial landmarks were assessed for 30 15(1/2)-year-old British-Caucasian children (15 males and 15 females). The sample was recruited from the Avon Longitudinal Study of Parents and Children (ALSPAC). The 3D facial images were acquired for each subject using two high-resolution Konica/Minolta laser scanners. Twenty-one facial landmarks (63 X, Y, and Z coordinates) were identified and recorded on each 3D facial image by two examiners. The reproducibility of landmarks identification at 2-week interval was assessed for one of the examiners (intra-examiner). In addition, the reproducibility of landmarks was assessed between the two examiners (inter-examiner). Using Bland-Altman plots, both intra- and inter-examiner assessments had evaluated landmarks reproducibility in three dimensions for the sample divided by gender. The reproducibility of the 3D-coordinates for each landmark was considered under three categories (< 0.5 mm, < 1 mm, and >1 mm) for both intra- and inter-examiner reproducibility assessments.
The distribution of coordinates at the three levels of reproducibility show the following percentages: intra-examiner: < 0.5 mm (38%), < 1 mm (51%), >1 mm (11%); inter-examiner: < 0.5 mm (35%), < 1 mm (48%), >1 mm (17%). Generally, 10 landmarks were reproducible to less than 1 mm for both intra- and inter-examiner reproducibility assessments. The Labiale Superius was the most reproducible and Palebrale Superius was the least reproducible landmark. Some landmarks showed greater reliability in certain planes of space; the Glabella was more reliable in the Z than the Y axis. Gender differences were found; Subnasale was more reproducible in the Y-axis in males compared with females.
The reproducibility of facial landmarks should be considered in the three planes of space. The majority of X-Y-Z coordinates taken to the 21 facial landmarks were reproducible to < 1 mm which is clinically acceptable. The accuracy of landmarks identification ranged from 0.39 to 1.49 mm. The reliability in identification depends on the clarity and definition of each landmark as well as gender characteristics. The different landmarks reproducibility should be considered when evaluating changes related to growth and healthcare interventions.
三维（3D）测量技术有助于在空间的三个平面（X、Y和Z）中检查面部形状。最近的研究致力于利用面部软组织标志点分析颅面形态，以识别不同人群之间的面部差异。面部标志点的可重复性对于确保准确的3D面部测量几乎是必不可少的。
本研究旨在评估使用激光扫描3D成像技术对面部软组织标志点的可重复性。
对30名15.5岁的英国白种儿童（15名男性和15名女性）进行面部标志点评估。样本来自阿冯父母与儿童纵向研究（ALSPAC）。使用两台高分辨率柯尼卡/美能达激光扫描仪为每个受试者采集3D面部图像。两名检查人员在每张3D面部图像上识别并记录21个面部标志点（63个X、Y和Z坐标）。对其中一名检查人员在2周间隔时标志点识别的可重复性进行评估（检查人员内部）。此外，还评估了两名检查人员之间标志点的可重复性（检查人员间）。使用布兰德-奥特曼图，检查人员内部和检查人员间评估均按性别对样本在三个维度上评估了标志点的可重复性。对于检查人员内部和检查人员间的可重复性评估，每个标志点的3D坐标的可重复性分为三类（<0.5毫米、<1毫米和>1毫米）。
在三个可重复性水平上坐标的分布显示出以下百分比：检查人员内部：<0.5毫米（38%），<1毫米（51%），>1毫米（11%）；检查人员间：<0.5毫米（35%），<1毫米（48%），>1毫米（17%）。一般来说，对于检查人员内部和检查人员间的可重复性评估，10个标志点的可重复性小于1毫米。上唇点是最具可重复性的标志点，而眶上点是可重复性最低的标志点。一些标志点在特定的空间平面上显示出更高的可靠性；眉间点在Z轴上比在Y轴上更可靠。发现了性别差异；男性鼻下点在Y轴上的可重复性高于女性。
应在空间的三个平面上考虑面部标志点的可重复性。用于21个面部标志点的大多数X-Y-Z坐标的可重复性小于1毫米，这在临床上是可接受的。标志点识别的准确性范围为0.39至1.49毫米。识别的可靠性取决于每个标志点的清晰度和定义以及性别特征。在评估与生长和医疗保健干预相关的变化时，应考虑不同标志点的可重复性。
