The effect of CT scanning and metal artefact reduction strategies on measuring knee implant displacement: iMAR – helpful or harmful?

IF 3.2 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

European Journal of Radiology Pub Date : 2025-07-04 DOI:10.1016/j.ejrad.2025.112281

Maaike A. ter Wee , Rogier P.J. Speelman , Johannes G.G. Dobbe , Arthur J. Kievit , Mario Maas , Leendert Blankevoort , Geert J. Streekstra

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引用次数: 0

Abstract

Background

A recent development in diagnosing total knee arthroplasty (TKA) tibial component loosening uses Computed Tomography (CT) images of loaded knees to assess implant micro-motion, but metal artefacts can affect reliability. This study investigates the impact of increased exposure and tube voltage, iterative metal artefact reduction reconstruction (iMAR), Sn-filtering and an extended CT scale (ECTS), compared to a standard knee CT protocol on load-induced implant displacement measurement.

Method

CT scans of a fresh frozen cadaver leg with a TKA were acquired using a standard protocol and four metal artefact reduction strategies: Increased exposure/tube voltage, iMAR, Sn-filtering, and ECTS reconstruction. Each scan was repeated 10 times with random leg repositioning ensuring no implant-bone motion. Image analysis included implant and proximal tibial cortex segmentation, object registration across scans, and quantification of apparent relative displacement. Grey-level similarity was assessed using the correlation coefficient (CC). Implant displacement error was measured using translation and rotation norms, mean target registration error (mTRE), and maximum total point motion (MTPM).

Results

CT scans with metal artefact reduction showed less noise and streaking. Grey-level similarity of the implant was similar across protocols (CC = 0.88). iMAR had the highest bone similarity (CC = 0.99). Implant displacement errors were comparable for increased exposure/tube voltage, Sn-filtering and ECTS (median: 0.08 mm translation, 0.13° rotation, 0.09 mm mTRE, 0.14 mm MTPM). However, iMAR statistically significantly increased median rotation norm to 0.19˚.

Conclusion

Increased exposure/tube voltage, Sn-filtering, and ECTS do not impact the measurement error of 3D CT-based knee implant loosening detection. iMAR showed increased rotational error while other displacement parameters remained unchanged, suggesting it may be less suitable for quantifying implant displacement.

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CT扫描和金属伪影复位策略对测量膝关节假体位移的影响：iMAR -有益还是有害？

背景：在全膝关节置换术（TKA）胫骨构件松动诊断中，最近的一项进展是使用加载膝关节的计算机断层扫描（CT）图像来评估植入物的微运动，但金属伪影会影响可靠性。本研究探讨了与标准膝关节CT方案相比，增加暴露和管电压、迭代金属伪影还原重建（iMAR）、sn滤波和扩展CT尺度（ECTS）对负载诱导植入物位移测量的影响。方法采用标准方案和四种金属伪影减少策略（增加暴露/管电压、iMAR、sn滤波和ECTS重建）对新鲜冷冻尸体腿进行ct扫描。每次扫描重复10次，随机重新定位腿部，确保无植入骨运动。图像分析包括植入物和胫骨近端皮质分割，扫描对象配准，以及表观相对位移的量化。采用相关系数（CC）评价灰色相似度。使用平移和旋转规范、平均目标配准误差（mTRE）和最大总点运动（MTPM）测量种植体位移误差。结果金属伪影还原后的ct扫描显示噪音和条纹减少。不同方案植入物的灰色相似度相似（CC = 0.88）。iMAR骨相似度最高（CC = 0.99）。植入物位移误差与增加的暴露/管电压、sn滤波和ECTS相当（中位数：0.08 mm平移，0.13°旋转，0.09 mm mTRE, 0.14 mm MTPM）。然而，iMAR统计学上显著提高了中位旋转规范至0.19˚。结论增加暴露/管电压、sn滤波和ECTS对三维ct膝关节假体松动检测的测量误差没有影响。iMAR显示旋转误差增加，而其他位移参数保持不变，提示iMAR可能不太适合量化种植体位移。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

European Journal of Radiology 医学-核医学

CiteScore

6.70

自引率

3.00%

发文量

398

审稿时长

42 days

期刊介绍： European Journal of Radiology is an international journal which aims to communicate to its readers, state-of-the-art information on imaging developments in the form of high quality original research articles and timely reviews on current developments in the field. Its audience includes clinicians at all levels of training including radiology trainees, newly qualified imaging specialists and the experienced radiologist. Its aim is to inform efficient, appropriate and evidence-based imaging practice to the benefit of patients worldwide.