Left ventricular global myocardial strain assessment comparing the reproducibility of four commercially available CMR-feature tracking algorithms

To compare the reproducibility of cardiovascular magnetic resonance feature-tracking (CMR-FT) packages to assess global left ventricular (LV) myocardial strain. In 45 subjects (i.e. 15 controls, 15 acute myocardial infarction, 15 dilated cardiomyopathy patients), we determined inter-vendor, inter-observer (two readers) and intra-observer reproducibility of peak systolic global radial, circumferential and longitudinal strain (GRS, GCS and GLS, respectively) comparing four commercially available software packages. Differences between vendors were assessed with analysis of variance (ANOVA), between observers and readings with intraclass correlation coefficient (ICC) and coefficient of variation (CV). The normalised end-diastolic volume was 91, 77 and 119 ml/m² (median, Q1, Q3) and ejection fraction was 41 ± 14%, range 12-67%. Global longitudinal strain (GLS), global circumferential strain (GCS) and global radial strain (GRS) values were 13.9% ± 5.4% (3.9-23.8%), 12.2% ± 5.8% (1.0-25.1%) and 32.0% ± 14.7 (3.6-67.8%), respectively. ANOVA showed significant differences between vendors for GRS (p < 0.001) and GLS (p = 0.018), not for GCS (p = 0.379). No significant bias was found for both intra- and inter-observer variability. The ICC for inter- and intra-observer reproducibility ranged 0.828-0.991 and 0.902-0.997, respectively. The CV, however, ranged considerably, i.e. 4.0-28.8% and 2.8- 27.7% for inter- and intra-observer reproducibility, respectively. In particular, for GRS differences in CV values between vendors were large, i.e. 5.2-28.8% and 2.8-27.7%, for inter- and intra-observer reproducibility, respectively. In a cohort of subjects with a wide range of cardiac performances, GRS and GLS values are not interchangeable between vendors. Moreover, although intra- and inter-observer reproducibility amongst vendors is excellent, some vendors encounter problems to reproducibly measure global radial strain. (orig.)