Power Doppler dual-frame triggering of myocardial contrast echocardiography: a quantitative video intensity analysis

The purpose of this study was to define the pattern of myocardial contrast observed during triggered dual-frame power Doppler imaging.

Ten patients with no previous history of myocardial infarction underwent a continuous intravenous infusion of Optison at 0.5 ml/min. Triggered, sequential dual-frame power Doppler imaging was performed from an apical four-chamber view using a prototype Acuson Sequoia imaging system. The average triggering interval was once every four cardiac cycles, and the average interval between sequential frames was 50 msec. Video intensity analysis was performed in five myocardial regions of interest, and the percent decrease in video intensity of the destruction frames in each region of interest was determined by subtracting the destruction frame video intensity from the fill frame video intensity. The percent decrease in video intensity varied significantly by myocardial location (P < 0.001), with greater destruction seen in the apical than in the basal regions.

This preliminary study demonstrates that power Doppler dual-frame triggering produces nonuniform decreases in video intensity, which likely represent nonuniform microbubble destruction. These results have important implications for the interpretation of myocardial perfusion patterns using this technique.