Echocardiographic strain imaging, also known as deformation imaging, has been developed as a means to objectively quantify regional and global myocardial function. First introduced as a post-processing feature of tissue Doppler imaging velocity converted to strain and strain rate, strain imaging has more recently also been derived from speckle tracking analysis. Tissue Doppler imaging yields velocity information from which strain and strain rate are mathematically derived whereas two-dimensional speckle tracking yields strain information from which strain rate and velocity data are derived. Data obtained from these two different techniques may not be equivalent due to limitations inherent with each technique. Speckle tracking analysis can generate longitudinal, circumferential, and radial strain measurements and left ventricular twist. Although potentially useful, these measurements are also complicated and frequently displayed as difficult-to-interpret waveforms. Strain imaging is now considered a robust research tool and has great potential to play many roles in routine clinical practice. This chapter explains the fundamental concepts of deformation imaging, the technical features of strain imaging using tissue Doppler imaging and speckle tracking, and the strengths and weaknesses of these methods.
