Towards standardized postprocessing of global longitudinal strain by feature tracking – OptiStrain CMR-FT study

Abstract

BackgroundLeft 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.MethodsWe 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).ResultsCompared 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.ConclusionStandardization 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.

Head‐to‐head comparison of cardiovascular MR feature tracking cine versus acquisition‐based deformation strain imaging using myocardial tagging and strain encoding

“…This is often cited as the main reason why clinical routine implementation is lagging. Training and standardisation may overcome the bias introduced by inconsistent software application and will probably lead to reduced observer‐induced variability 18,36 . Despite high consistency and correlation among vendors, differences in absolute agreement and absolute strain values suggest a requirement for software‐specific reference values and furthermore a need for further standardisation to allow easy clinical routine implementation.…”

“…Training and standardisation may overcome the bias introduced by inconsistent software application and will probably lead to reduced observer-induced variability. 18,36 Despite high consistency and correlation among vendors, differences in absolute agreement and absolute strain values suggest a requirement for software-specific reference values and furthermore a need for further standardisation to allow easy clinical routine implementation. Beyond limited agreement within FT-derived deformation assessment, the current data demonstrate distinct deviations for different approaches applied to evaluate myocardial deformation.…”

Intra- and inter-observer reproducibility of multilayer cardiac magnetic resonance feature tracking derived longitudinal and circumferential strain

“…Heinke et al (17) described a post-processing standardisation of deriving CMR-FT GLS in which assessors evaluated the quality of contour placement following manual delineation and performed adjustments as necessary based on evidence of poor tracking. This approach was shown to improve intra-and inter-observer agreement when comparing pre-and post-standardisation data.…”

Direct comparison of multilayer left ventricular global longitudinal strain using CMR feature tracking and speckle tracking echocardiography

“…Secondly, strain analysis was performed using only a single software. The literature shows that inter-vendor reproducibility is a limiting factor for routine implementation of CMR-FT in clinical practice, with a recent study by Heinke et al highlighting the need for standardised postprocessing of GLS measurements in reducing variability [ 25 ]. Although this study focusses on global strain, the issue of intervendor variability has also been reported in measuring multi-layer segmental strain [ 26 ].…”