Miles James E, Buelund Lene E
Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 16, 1870, Frederiksberg C, Denmark.
BMC Biomed Eng. 2021 Feb 1;3(1):2. doi: 10.1186/s42490-021-00047-7.
Multiplanar reconstructions of computed tomography (CT) scans can alleviate issues with bone or joint positioning during scan acquisition. The repeatability of these reconstructions is dependent on human operators applying reconstruction criteria, and therefore is subject to error, which could affect measurement reliability for angular or spatial measurements made for orthopaedic surgery. We describe a method for quantifying inter-reconstruction variability numerically and graphically using metadata from the CT header to find vectors describing reconstruction axis alignment. The approach is demonstrated using 3 sets of computed tomographic reconstructions of 24 vulpine femorotibial joints.
Vectors describing axis alignments permitted identification and subsequent analysis of deviations from optimal alignment between reconstruction sets. For the worked example, alignment deviations equivalent to femoral abduction/adduction were nearly twice those for extension/flexion, and simulation of the effects of these deviations on measurements closely matched published data.
The method presented here is straightforward and permits numerical and graphical analysis of reconstruction variability. Reconstruction alignment variability should be considered before adopting new reconstruction criteria for clinical use, and evaluated whenever there is suspicion that reconstruction variability could unduly influence subsequent measurements. These evaluations may help drive improvements in reconstruction criteria. The methods described here could also be employed for comparing patient positioning between scans and between different scan modalities.
计算机断层扫描（CT）的多平面重建可缓解扫描采集过程中骨骼或关节定位的问题。这些重建的可重复性取决于操作人员应用重建标准，因此容易出现误差，这可能会影响骨科手术中角度或空间测量的可靠性。我们描述了一种利用CT头部的元数据以数字和图形方式量化重建间变异性的方法，以找到描述重建轴对齐的向量。使用24个狐科动物股胫关节的3组计算机断层扫描重建来演示该方法。
描述轴对齐的向量允许识别并随后分析重建集之间与最佳对齐的偏差。对于实例，相当于股骨外展/内收的对齐偏差几乎是伸展/屈曲偏差的两倍，并且这些偏差对测量影响的模拟与已发表的数据非常匹配。
本文提出的方法简单明了，允许对重建变异性进行数字和图形分析。在采用新的重建标准用于临床之前，应考虑重建对齐变异性，并且每当怀疑重建变异性可能过度影响后续测量时都应进行评估。这些评估可能有助于推动重建标准的改进。这里描述的方法也可用于比较扫描之间以及不同扫描模式之间的患者定位。
