Institute of Experimental and Translational Cardiac Imaging DZHK Centre for Cardiovascular Imaging Goethe University Hospital Frankfurt, Theodor-Stern Kai 7, 60590, Frankfurt am Main, Germany.
Department of Cardiovascular Imaging, Menzies Institute for Medical Research, Hobart, Tasmania, Australia.
BMC Cardiovasc Disord. 2019 Nov 27;19(1):267. doi: 10.1186/s12872-019-1255-4.
Left ventricular global longitudinal strain (GLS) with cardiovascular magnetic resonance (CMR) is an important prognostic biomarker. Its everyday clinical use is limited due to methodological and postprocessing diversity among the users and vendors. Standardization of postprocessing approaches may reduce the random operator-dependent variability, allowing for comparability of measurements despite the systematic vendor-related differences.
We investigated the random component of variability in GLS measurements by optimization steps which incrementally improved observer reproducibility and agreement. Cine images in two-, three- and four-chamber-views were serially analysed by two independent observers using two different CMR-FT softwares. The disparity of outcomes after each series was systematically assessed after a number of stepwise adjustments which were shown to significantly reduce the inter-observer and intervendor bias, resulting standardized postprocessing approach. The final analysis was performed in 44 subjects (ischaemic heart disease n = 15, non-ischaemic dilated cardiomyopathy, n = 19, healthy controls, n = 10). All measurements were performed blind to the underlying group allocation and previous measurements. Inter- and intra-observer variability were tested using Bland-Altman analyses, intra-class correlation coefficients (ICCs) and coefficients of variation (CVs).
Compared to controls, mean GLS was significantly lower in patients, as well as between the two subgroups (p < 0.01). These differences were accentuated by standardization procedures, with significant increase in Cohen's D and AUCs. The benefit of standardization was also evident through improved CV and ICC agreements between observers and the two vendors. Initial intra-observer variability CVs for GLS parameters were 7.6 and 4.6%, inter-observer variability CVs were 11 and 4.7%, for the two vendors, respectively. After standardization, intra- and interobserver variability CVs were 3.1 and 4.3%, and 5.2 and 4.4%, respectively.
Standardization of GLS postprocessing helps to reduce the random component of variability, introduced by inconsistencies of and between observers, and also intervendor variability, but not the systematic inter-vendor bias due to differences in image processing algorithms. Standardization of GLS measurements is an essential step in ensuring the reliable quantification of myocardial deformation, and implementation of CMR-FT in clinical routine.
心血管磁共振（CMR）的左心室整体纵向应变（GLS）是一种重要的预后生物标志物。由于使用者和供应商之间的方法和后处理多样性，其日常临床应用受到限制。后处理方法的标准化可能会降低随机的、依赖操作者的变异性，从而允许尽管存在与供应商相关的系统差异，但仍可以对测量结果进行比较。
我们通过逐步改进观察者可重复性和一致性的优化步骤，研究了 GLS 测量中的随机变异性组成部分。使用两种不同的 CMR-FT 软件，两名独立观察者在二维、三维和四腔心视图中对电影图像进行连续分析。在一系列调整之后，系统地评估了每个系列之后结果的差异，这些调整显著降低了观察者间和供应商间的偏差，从而实现了标准化的后处理方法。最后分析在 44 名受试者（缺血性心脏病 n=15、非缺血性扩张型心肌病 n=19、健康对照 n=10）中进行。所有测量均在不知道基础分组和先前测量的情况下进行。使用 Bland-Altman 分析、组内相关系数（ICC）和变异系数（CV）来测试观察者内和观察者间的可变性。
与对照组相比，患者的平均 GLS 明显降低，两个亚组之间也存在差异（p<0.01）。通过标准化程序，这些差异更加明显，Cohen's D 和 AUC 显著增加。观察者和两个供应商之间观察者间和观察者内的 CV 和 ICC 协议的改善也表明了标准化的益处。GLS 参数的初始观察者内变异性 CV 分别为 7.6%和 4.6%，观察者间变异性 CV 分别为 11%和 4.7%，对于两个供应商。标准化后，观察者内和观察者间变异性 CV 分别为 3.1%和 4.3%和 5.2%和 4.4%。
GLS 后处理的标准化有助于减少观察者之间和观察者内不一致性引入的随机变异性，以及供应商之间的变异性，但不能减少由于图像处理算法差异引起的系统供应商偏差。GLS 测量的标准化是确保心肌变形可靠量化并将 CMR-FT 应用于临床常规的重要步骤。
