In vivo measurement of small velocity signals and change in thickness of the heart walls

We have previously developed a new method for accurately tracking the movement of the heart wall based on both the phase and magnitude of the demodulated signals to determine the instantaneous position of an object. By this method, velocity signals of the heart wall with small amplitudes less than several micrometers on the motion resulting from a heartbeat can be accurately detected. Moreover, the method has been applied to multiple points preset in the heart wall along an ultrasonic beam so that the spatial distributions of the local change in thickness during one cardiac cycle is determined. In this paper, the method is applied to the free wall of the right ventricle (RV), the interventricular septum (IVS), and the posterior wall of the left ventricle (LV). From the relationships among the results for these parts of the heart, new findings which characterize the velocity signals and the change in thickness in each cardiac period are described. This method offers potential for quantitative myocardial diagnosis.