Noninvasive myocardial strain measurement by speckle tracking echocardiography - Validation against sonomicrometry and tagged magnetic resonance imaging

OBJECTIVES The aim of this study was to validate speckle tracking echocardiography (STE) as a method for angle-independent measurement of regional myocardial strain, using sonomicrometry and magnetic resonance imaging (MRI) tagging as reference methods. BACKGROUND Tissue Doppler imaging allows non-invasive measurement of myocardial strain in the left ventricle (LV), but is limited by angle dependency. METHODS Strain measurements with STE were obtained by a Custom-made program that allowed tracking of two-dimensional motion of speckle patterns in a B-mode image. In anesthetized clogs, we compared LV long- and short-axis measurements by STE to sonomicrometry during preload changes and regional myocardial ischemia. Measurements in the two orthogonal axes were obtained simultaneously in a single imaging plane. In human subjects, long-axis strain by STE and MRI tagging were compared in multiple segments of the LV. RESULTS In the experimental study there was good correlation and agreement between STE and sonomicrometry for systolic strain in the long axis (r = 0.90, p < 0.001; 95% limits of agreement -4.4% to 5.0%) and systolic shortening in the short axis (r = 0.79, p < 0.001; -5.6% to 5.1%). In the clinical study, 80% of the segments could be analyzed, and correlation and agreement between STE and MRI tagging were good (r = 0.87, p < 0.001; -9.1% to 8.0%). CONCLUSIONS Speckle tracking echocardiography provides accurate and angle-independent measurements of LV dimensions and strains and has potential to become a clinical bedside tool for quantifying myocardial strain.