Objectives: Myocardial contrast echocardiography observes heterogeneous opacification between regions near and far from the transducer depending on the depth of the focus point. The efficacy of the multi-focus setting was investigated for the improvement of this heterogeneous opacification of the myocardium in myocardial contrast echocardiography.
Methods: Myocardial contrast echocardiography was performed in five closed-chest dogs using triggered (every fourth cardiac cycle) second harmonic technology (1.8/3.6 MHz) following intravenous injection of 0.1 ml of Optison. The short-axis view of the left ventricle was recorded and baseline subtracted video intensity (peak intensity) was calculated in the anterior, septal and posterior left ventricular walls to evaluate myocardial opacification. Three different single foci at near (2 cm), middle (4 cm), and far (6 cm) points were examined, as well as the multi-focus setting combining the near and far foci.
Results: Using any single focus point, the peak intensities of segments far from the focus points were decreased and heterogeneous myocardial opacification was observed. Only the multi-focus setting demonstrated absence of differences in peak intensities between each segment with sufficient myocardial opacification of all segments.
Conclusions: The multi-focus setting may be advantageous for improving the heterogeneity of myocardial opacification in myocardial contrast echocardiography.