Effects of shadowing on the time-intensity curves in contrast echocardiography: a phantom study

Literature states that the inability of myocardial contrast echocardiography to assess differences in flow between regions could be related to myocardial shadowing. In this study, we evaluate this effect on the time-intensity curves. In a perfusion phantom, shadowing was induced by high concentrations of a contrast agent (approximately 1 x 10(8) bubbles/mL), and evaluated for different flows (50-270 mL/min). The high concentration resulted in an increase of the video-intensity in regions of interest close to the transducer (2 mm) and a marked reduction in remote areas (20 mm). The peak intensity of the time-intensity curves did not correlate with flow (range r = 0.1, 0.37), while the inverse area under the curve correlated strongly (r = 0.98). The inverse curve width and the decay after peak intensity also correlated excellently with flow (r = 0.99 and range r = 0.97, 0.99). We opt for the decay as transmural flow indicator using contrast echocardiography, since this parameter is least affected by shadowing.