University of Minnesota, Minneapolis, 55455, USA.
Angle Orthod. 2011 Mar;81(2):245-52. doi: 10.2319/041810-210.1.
To determine the influence of landmark labeling on the accuracy and precision of an indirect facial anthropometric technique.
Eighteen standard linear craniofacial measurements were obtained from 10 adults using the 3dMDface system, with landmarks labeled (Labeled_3D) and without landmarks labeled (Unlabeled_3D) before image acquisition, and these were compared with direct anthropometry (Caliper). Images were acquired twice in two different sessions 1 week apart (T1 and T2). Accuracy and precision were determined by comparing mean measurement values and absolute differences between the three methods.
Mean measurements derived from three-dimensional (3D) images and direct anthropologic measurements were mostly similar. However, statistically significant differences (P < .01) were noted for seven measurements in Labeled_3D and six measurements in Unlabeled_3D. The magnitudes of these differences were clinically insignificant (<2 mm). In terms of precision, results demonstrated good reproducibility for both methods, with a tendency toward more precise values in Labeled_3D, when compared with the other two techniques (P < .05). We found that Labeled_3D provided the most precise values, Unlabeled_3D produced less precise measurements, and Caliper was the least capable of generating precise values.
Overall, soft tissue facial measurement with the 3dMDface system demonstrated similar accuracy and precision with traditional anthropometry, regardless of landmarking before image acquisition. Larger disagreements were found regarding measurements involving ears and soft tissue landmarks without distinct edges. The 3dMDface system demonstrated a high level of precision, especially when facial landmarks were labeled.
确定标志点标记对面部间接测量技术准确性和精密度的影响。
使用 3dMDface 系统，对 10 名成年人进行了 18 项标准线性颅面测量，在图像采集前分别进行了标志点标记（Labeled_3D）和未标记（Unlabeled_3D），并与直接人体测量（卡尺）进行了比较。图像在相隔 1 周的 2 个不同时段（T1 和 T2）中采集了 2 次。通过比较三种方法的平均测量值和绝对差值，确定了准确性和精密度。
来自三维（3D）图像和直接人体测量的平均测量值大多相似。然而，在 Labeled_3D 中有 7 项测量值和在 Unlabeled_3D 中有 6 项测量值存在统计学显著差异（P<0.01）。这些差异的大小在临床上无意义（<2mm）。就精密度而言，两种方法均表现出良好的可重复性，与其他两种技术相比，Labeled_3D 具有更精确的趋势（P<0.05）。我们发现，Labeled_3D 提供了最精确的测量值，Unlabeled_3D 产生了不太精确的测量值，而卡尺则最不能生成精确的测量值。
总体而言，无论在图像采集前是否进行标志点标记，3dMDface 系统的软组织面部测量与传统人体测量具有相似的准确性和精密度。对于涉及无明显边缘的耳朵和软组织标志点的测量，发现较大的差异。3dMDface 系统表现出高精度，尤其是当对面部标志点进行标记时。
