Fetal speckle-tracking echocardiography: a comparison between two-dimensional and electronic spatio-temporal image correlation (e-STIC) technique

Background: Speckle tracking technology has been applied to assess ventricular deformation throughout the cardiac cycle. An electronic four dimensional probe that allows rapid acquisition of electronic spatio-temporal image correlation volumes (eSTIC) has been recently introduced. Objectives: The aim of our study was to investigate whether e-STIC acquisition improves deformation analyses reproducibility. Study design: We recruited fetuses between 20 and 40 weeks of gestation. We obtained a 2D video clip and an e-STIC volume of a four-chamber view. We focused on left ventricular global strain (LV-GS) and left ventricular ejection fraction (LV-FE). Intraobserver, interobserver and intermethod agreement were assessed by means of intraclass correlation coefficient (ICC) and illustrated by Bland-Altman plots. Systematic differences between measurements were assessed using a paired t-test. Results: The mean difference between LV-GS values obtained with e-STIC and 2D analysis was −0.10 (95% CI −2.28, 2.08). No systematic differences were found between the two techniques for LV-GS values (p-value =.927). The mean difference between LV-FE values obtained with e-STIC and 2D analysis was 7.55 (95% CI 4.16, 10.95; p-value <.001). The inter-rater reliability of LV-GS was moderate-to-substantial for both e-STIC and 2D. The inter-rater reliability of LV-FE obtained via e-STIC was superior to that obtained via 2D analysis. The intra-rater reliability of LV-GS obtained with e-STIC was superior to that obtained with 2D analysis (ICC 0.857; 95% IC 0.761–0.917). The intra-rater reliability of LV-FE obtained via e-STIC was superior to that obtained via 2D analysis (ICC 0.647; IC 0.51–0.783). Conclusions: e-STIC seems to be a better technique than 2D analysis for intra-rater reliability of LV-GS. 4D acquisition might improve intrinsic limitations of speckle tracking echocardiography.