High spatial resolution speckle tracking improves accuracy of 2-dimensional strain measurements: An update on a new method in functional echocardiography

Background: We previously found that a 2-dimensional (2D) strain echocardiography method had some limitations in the assessment of low magnitudes and rates of deformation. Here, we study whether a recently introduced high spatial resolution speckle tracking (HRT) method improves accuracy of 2D strain measurements. Methods: A gelatin block was cyclically compressed by a hydraulic piston. Regional deformations measured by 2D-HRT were compared with reference strains obtained from an embedded pair of sonomicrometry crystals. Global deformations (along the gelatin block) were compared to strains calculated from tracings of piston motion. We tested a wide range of strains (5.4%-21.5%) and combined each measurement with simulated heart rates (24-196/min). Results: Regional deformations measured by 2D-HRT demonstrated excellent correlation (r = 0.99, P <.0001) and agreement (bias +/- 2SD = -0.3 +/- 1.3%) with sonomicrometry. Close correlation (r 0.99, P <.0001) and agreement (bias +/- 2SD = 0.5 +/- 1.2%) was observed also for global strains measured by 2D-HRT and compared with tracings of piston motion. There was good reproducibility of all tests: interobserver and intraobserver variabilities were 3.2% and 3.4% for regional strains and 3.1% and 3.5% for global strains, respectively. Conclusion: In our in vitro setting, the 2D-HRT method produced precise and accurate measurements of strains for clinically relevant ranges of deformation magnitudes and ranges.