Each patient underwent MCE examination (IE33, Philips Ultrasound, Andover, Massachusetts) using an S3 transducer and the preset low mechanical index (MI) imaging in power modulation mode (operating frequency 2.5 MHz). The default MI was 0.10, with small variation (0.09 to 0.15) according to the imaging depth. A peripheral infusion of sulfur hexafluoride (Sonovue, Bracco Diagnostics Inc., Milan, Italy) was commenced at 0.7 ml/min and adjusted in 0.1-ml/min steps to achieve optimum myocardial opacification. Optimum myocardial opacification was defined as homogeneous left ventricular opacification combined with at least mild homogeneous opacification of myocardial segments without attenuation or shadow artifacts. Once “steady state” was reached, resting images were acquired in the 3 apical long-axis views. Single-beat loops were acquired during short breath holds and were stored digitally.

For stress imaging, intravenous adenosine (140 μg/kg/min) was administered for 4 minutes, or less if angina was induced or if perfusion/wall motion abnormalities became apparent.

During the infusion, the same imaging dataset (comprising 2-, 3-, and 4-chamber apical views) was sequentially acquired at approximately 1-min intervals, with storage of multiple cineloops for each view. Patients were monitored continuously by electrocardiography, sphygmomanometry, and pulse oximetry.

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http://imaging.onlinejacc.org/article.aspx?articleid=1109666

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For perfusion assessment, rest and stress images were displayed side by side. A perfusion defect was defined as a decrease in contrast enhancement relative to another region with comparable image quality.

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Results: Compared with X-ray angiography, MCE provided diagnostic accuracy of 82%, sensitivity of 85%, and specificity of 76% for detecting significant coronary stenosis. Disease location was also identified with reasonable accuracy (diagnostic accuracy 81% for left anterior descending disease, 77% for left circumflex artery disease, and 84% for right coronary artery disease). With CMR as the reference standard for functional assessment, MCE provided diagnostic accuracy of 79%, sensitivity of 85%, and specificity of 74%. Interobserver agreement for MCE was 79% (95% confidence interval: 67% to 88%)..