Evaluation of transmural myocardial deformation and reflectivity characteristics

Several physical properties of the myocardium, such as velocity, strain rate, strain, the mean reflected ultrasonic energy and its cyclic variation have been measured to assess regional myocardial function. Prior studies have merely focused on extracting one of these parameters at a time. Moreover, their temporal resolution was often compromised and the methodology used, did often not allow to detect transmural changes of these properties. The purpose of this study was to overcome these limitations by extracting all these parameters simultaneously in different layers of the cardiac wall at a high temporal resolution. The study showed significant changes of all parameters transmurally. Radial velocities showed a marked endo- to epicardial velocity gradient. Radial strain rate and strain were highest in the mid-myocardium, although relatively low in other layers. Finally, integrated backscatter patterns showed a complex but reproducible behavior at high temporal resolution. Their cyclic variation showed to be higher in layers exhibiting more strain. These results show that the sub-endo- and sub-epicardial fibers do not contribute significantly to the radial thickening of the posterior wall. Moreover, the observations made for the transmural integrated backscatter behavior are in concordance with the hypothesis that changes in integrated backscatter are directly related to the total regional (three-dimensional) strain.