Pitfalls in the accurate measurement of joint space narrowing in semiflexed, anteroposterior radiographic imaging of the knee.
Pitfalls in the accurate measurement of joint space narrowing in semiflexed, anteroposterior radiographic imaging of the knee.
复制标题
膝关节半屈前后位放射线成像中精确测量关节间隙狭窄的缺陷。
DOI：
10.1002/art.20363
复制
发表时间：
2004
影响因子：
--
通讯作者：
Lequesne,Michel
中科院分区：
文献类型：
--
作者：
Mazzuca,StevenA;Brandt,KennethD;Buckwalter,KennethA;Lequesne,Michel
膝关节连续X线片半屈曲前后位（SF‐AP）视图关节间隙宽度（JSW）变化的计算机测量最近已被用作缓解疾病的骨关节炎药物（DMOAD）临床试验的主要结局指标。在使用X线透视实现内侧胫骨平台和X射线束的可再现对线时，SF‐AP放射学方案在检测关节间隙狭窄（JSN）方面的灵敏度高于传统放射学定位技术。然而，SF‐AP视图的实用性受到每次检查中X线穿透变化的影响，这可能会混淆膝关节AP视图中固有的X线摄影放大率对JSW自动测量的校正。最近一项使用SF‐AP方案的DMOAD试验显示，JSW不太可能增加≥0.50 mm（即，大于测量误差）。本报告提供了一个分析这个问题，和研究的目的是证明，替代JSW的自动估计与精确的手动测量可以显着减少问题归因于射线magnifications.MethodsSF-AP射线照片获得在基线，并在16个月和30个月后，从受试者参加了6个中心的DMOAD试验。对于每次检查，将一个6.35 mm钢球固定在腓骨头上方的皮肤上，以估计影像学放大率（%Mag）并校正JSW测量值。通过自动方法（边缘检测）和手动方法测量内侧胫股间室的最小骨间距（IBD）和%Mag。IBD和放大校正JSW估计中的%Mag的自动和手动测量的组合在其再现性、一致性和对JSN.ResultsWith全自动测量方面进行了比较，模拟X射线照片中的X射线穿透变化和数字X射线照片中的边缘增强导致计算机“看到”一个直径被人为减小的金属球，导致JSW的测量值膨胀。使用IBD和%Mag的手动测量在很大程度上消除了这些问题，并将JSW增加≥0.50 mm的膝关节频率从16%降低至2%。在15个膝关节中的14个膝关节中，使用手动方法观察到JSW显著增加，这种JSW的增加可以通过研究期间显著的外侧间室狭窄或内侧平台对齐不良的发展来解释。SF‐AP视图中膝关节JSW测量的自动和手动方法具有相当的阅片员内重现性，手动方法不太容易受到影响影像学放大率原始JSW估计值校正的技术因素的影响。在我们能够确定这些技术问题的实际有效解决方案之前，必须谨慎使用DMOAD试验中涉及膝关节AP成像的任何放射学方案。
ObjectiveComputerized measurement of changes in joint space width (JSW) on serial radiographs of the knee in the semiflexed, anteroposterior (SF‐AP) view has been used recently as a primary outcome measure in clinical trials of disease‐modifying osteoarthritis drugs (DMOADs). In the use of fluoroscopy to achieve reproducible alignment of the medial tibial plateau and x‐ray beam, the SF‐AP radiographic protocol affords greater sensitivity in the detection of joint space narrowing (JSN) than that achieved by conventional radiographic positioning techniques. However, the utility of the SF‐AP view is compromised by the variation in x‐ray penetration in each examination, which may confound the correction of the automated measurement of JSW for the radiographic magnification inherent in an AP view of the knee. A recent DMOAD trial using the SF‐AP protocol showed an improbable increase in JSW of ≥0.50 mm (i.e., greater than the measurement error). The present report provides an analysis of this problem, and the study aim was to demonstrate that substitution of the automated estimates of JSW with precise manual measurements can markedly reduce the problem attributable to radiographic magnification.MethodsSF‐AP radiographs were obtained at baseline and at 16 months and 30 months thereafter from subjects enrolled in a 6‐center DMOAD trial. For each examination, a 6.35‐mm steel ball was affixed to the skin over the head of the fibula to permit estimation of the percentage of radiographic magnification (%Mag) and correction of JSW measurements. Measurements of the minimum interbone distance (IBD) in the medial tibiofemoral compartment and the %Mag were obtained by an automated method (edge detection) and manually. Combinations of automated and manual measurements of the IBD and %Mag in estimates of magnification‐corrected JSW were compared with respect to their reproducibility, agreement, and sensitivity to JSN.ResultsWith fully automated measurements, variations in x‐ray penetration in analog radiographs and edge enhancement in digital radiographs resulted in the computer “seeing” a metal ball whose diameter was artifactually reduced, resulting in an inflated measurement of JSW. Use of manual measurement of the IBD and %Mag largely eliminated these problems and reduced, from 16% to 2%, the frequency of knees exhibiting an increase in JSW ≥0.50 mm. In 14 of the 15 knees in which a significant increase in JSW was noted with the manual method, this increase in JSW could be explained by the development of significant lateral compartment narrowing during the study or poor alignment of the medial plateau.ConclusionAlthough automated and manual methods of JSW measurement of the knee in the SF‐AP view possess comparable intrareader reproducibility, the manual method is less susceptible to technical factors that affect the correction of raw JSW estimates for radiographic magnification. Until we can identify practical, effective solutions to these technical problems, use of any radiographic protocol involving AP imaging of the knee in a DMOAD trial must be viewed with caution.