P4A-2 An In-Vivo Study of Frame Rate Optimization for Myocardial Elastography

In this paper, the requirement and optimization of the frame rate for myocardial elastography was investigated in normal mice and humans in vivo. Using a retrospective electrocardiogram (ECG) gating technique, the highest frame rate was 8 kHz and 481 Hz, respectively. Axial displacement and strain of myocardium were estimated using an RF speckle tracking method consisting of a 1-D kernel in a 2-D search. The frame rate was then decimated to study its effects on the image quality of myocardial elastography, in terms of elastographic signal-to-noise (SNRe) and correlation coefficient. Trade-offs between SNRe and effective frame rate were identified in the murine case. The optimum range of frame rate was found to be between 2000 and 2700 Hz, or equivalently, 250-350 frames per cardiac cycle (fpc). In the human case, the image quality increased monotonously with the frame rate. A frame rate higher than 480 Hz (i.e., 350 fpc) was thus required for both systole and diastole.