Assessment of myocardial elastography performance using normal and ischemic phantoms undergoing physiological motion

Myocardial Elastography has been introduced as a non-invasive, ultrasound-based imaging, which can detect abnormalities in myocardial stiffness that cannot be detected with the current standard echocardiography used clinically. By acquiring radio-frequency (RF) frames at high frame rates (190-310 Hz), the deformation of the myocardium can be estimated, and used to identify regions of abnormal deformation indicative of ischemia. In this study, we pursue in vitro validation of ME using polyacrylamide phantoms. Phantoms of homogeneous stiffnesses and with stiff inclusions were imaged, and ME was applied. Rotational motion was mapped and distinguished from torsional motion. During expansion/contraction, if an inclusion was not present, the estimated strain patterns were smooth, while if an inclusion was present, abnormalities were observed which enabled identification of the inclusion. The average peak radial and circumferential strains were 2.1±0.3% and -2.0±1% for a normal phantom, and -0.07±0.9% and 0.3±0.6% for an ischemic phantom, respectively. This study shows ME to be capable of distinguishing between different types of motion configurations, and is sensitive to stiffness changes in tissue-mimicking phantoms.