Myocardial contrast echocardiography: advantages of quantitative analysis.

Every technology yet to be consolidated needs to be compared with reference methods to evaluate its accuracy. Over the past years, contrast echocardiography has been compared against a variety of standards. In experimental studies, myocardial perfusion data from ultrasound have been compared with the measurements of coronary blood flow obtained by labeled microspheres, or with infarct size following myocardial tissue staining. In initial clinical studies, hand-made contrast agents have been injected into the coronary arteries during cardiac catheterization, and myocardial contrast enhancement has been compared with angiographic coronary patency in the acute phase of the infarction, left ventricular recovery following myocardial reperfusion, and patient’s outcome. With the marketing of lung-crossing agents and the availability of technologies that make myocardial enhancement visible after intravenous contrast administration, it became natural to compare myocardial contrast echocardiography with a consolidated diagnostic tool such as SPECT. Contrast echocardiography and SPECT differ both in physical principles and in information provided. Specifically, myocardial contrast effect depends upon ultrasound-induced resonance or destruction of microbubbles in coronary microcirculation; thus, a regional contrast enhancement implies microvascular patency. Conversely, tracer uptake by SPECT requires the functional integrity of cell’s membrane in addition to a patent microcirculation. Still, myocardial contrast echocardiography has been compared with SPECT as this method is the most widely avail-