Measurements of transmural strain variations by two dimensional ultrasound speckle tracking

Background: Myocardial infarction (MI) is known to progress from the inner layers towards the epicardium. Since it is important to detect MI early, to prevent a negative remodeling process of the left ventricle (LV), the hypothesis of this study was that evaluation of layer-specific strains is feasible, and it will enable differentiation between subjects with large MI, small MI and normal LV. Methods: In this study a commercial speckle tracking echocardiography (STE) program was modified to measure the strains at three myocardial layers instead of for the total-wall-thickness. After a validation process by using software implemented phantoms, the commercial and modified programs were applied to echocardiography of 54 subjects. Results: The validation study results for 972 segments showed an agreement between the endocardial strains, manually measured by the commercial program, and automatically measured by the modified program. Finally, the algorithm was applied to scans of 15 normal subjects, 9 patients with small MI and to 6 patients with large MI. The results show that the strain elevated from the endocardium towards the epicardium for the normal and small MI groups, but not for the large MI group. Conclusions: In conclusion, the layer-specific STE method allows accurate analysis of the transmural variations of the strains.