Background

Functional disorders of the hand are generally investigated first using conventional radiographic imaging. However, X-rays (two-dimensional (2D)) provide limited information and the information may be reduced by overlapping bones and projection bias. This work presents a three-dimensional (3D) hand reconstruction method from biplanar X-rays.

Method

This approach consists of the deformation of a generic hand model on biplanar X-rays by manual and automatic processes. The reference examination being the manual CT segmentation, the precision of the method was evaluated by a comparison between the reconstructions from biplanar X-rays and the corresponding reconstructions from the CT scan (0.3 mm section thickness). To assess the reproducibility of the method, 6 healthy hands (6 subjects, 3 left, 3 men) were considered. Two operators repeated each reconstruction from biplanar X-rays three times to study inter- and intra-operator variability. Three anatomical parameters that could be calculated automatically from the reconstructions were considered from the bone surfaces: the length of the scaphoid, the depth of the distal end of the radius and the height of the trapezius.

Results

Double the root mean square error (2 Root Mean Square, 2RMS) at the point/area difference between biplanar X-rays and computed tomography reconstructions ranged from 0.46 mm for the distal phalanges to 1.55 mm for the bones of the distal carpals. The inter-intra-observer variability showed precision with a 95% confidence interval of less than 1.32 mm for the anatomical parameters, and 2.12 mm for the bone centroids.

Discussion

The current method allows to obtain an accurate 3D reconstruction of the hand and wrist compared to the traditional segmented CT scan. By improving the automation of the method, objective information about the position of the bones in space could be obtained quickly. The value of this method lies in the early diagnosis of certain ligament pathologies (carpal instability) and it also has implications for surgical planning and personalized finite element modeling.

Level of proof

Basic sciences.

中文翻译：

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双平面 X 射线手部三维重建：准确性和可靠性评估

背景

通常首先使用传统的放射线成像来研究手部的功能障碍。然而，X 射线（二维 (2D)）提供的信息有限，并且信息可能会因骨骼重叠和投影偏差而减少。这项工作提出了一种利用双平面 X 射线进行三维 (3D) 手部重建的方法。

方法

该方法包括通过手动和自动过程在双平面 X 射线上对通用手模型进行变形。参考检查是手动CT分割，通过比较双平面X射线重建和CT扫描（0.3毫米 切片厚度）的相应重建来评估该方法的精度。为了评估该方法的重现性，考虑了 6 只健康手（6 名受试者，3 名左手，3 名男性）。两名操作员将双平面 X 射线的每次重建重复三次，以研究操作员之间和内部的变异性。从骨表面考虑了可以从重建中自动计算的三个解剖参数：舟状骨的长度、桡骨远端的深度和斜方肌的高度。

结果

双平面 X 射线和计算机断层扫描重建之间的点/面积差异的双均方根误差（2 均方根，2RMS）范围从 远端指骨的 0.46 毫米到 远端腕骨的 1.55 毫米。观察者内部变异性显示出精确性， 解剖参数的 95% 置信区间小于 1.32 毫米， 骨质心的置信区间小于 2.12 毫米。

讨论

与传统分段 CT 扫描相比，当前方法可以获得手和手腕的准确 3D 重建。通过提高该方法的自动化程度，可以快速获得有关骨骼在空间中位置的客观信息。该方法的价值在于某些韧带病变（腕骨不稳定）的早期诊断，并且对手术计划和个性化有限元建模也具有影响。

证明级别

基础科学。