Fourier phase and amplitude analysis for automated objective evaluation of myocardial contrast echocardiograms

Objective methods for evaluating myocardial contrast echocardiography (MCE) are not yet widely available. We applied a Fourier analysis to myocardial contrast echocardiograms to identify myocardial perfusion defects.

Harmonic power-Doppler contrast echocardiograms were performed in 21 patients undergoing Tl-201-SPECT imaging and in 13 controls. Images were transformed using Fourier analysis to obtain phase of the first harmonic sinusoidal curve displayed as color coded sequence of myocardial intensity changes. Means and standard deviations of regional phase angles were measured. The method was validated in an in vitro model. A contrast filled latex balloon was imaged at different gain settings mimicking defined time-intensity curves. An intraoperative porcine infarction model served to prove feasibility of Fourier transformation to analyze real-time pulse inversion contrast echocardiography.

In patients, phase imaging and intensity analysis showed focal areas with marked phase shifts (106 +/- 90 degrees) and heterogeneous distribution of phase angles (SD 66 +/- 17 degrees), correctly identifying 13/14 perfusion defects. The in vitro validation yielded increasing phase angles with increasing beta-values. This method was successfully applied to real-time MCE, identifying all infarction areas during occlusion of the left anterior descending artery.

Phase analysis can be used to display dynamics of myocardial opacification.