Clinical Applications of Contrast Echocardiography

One of the most recent revolutions of echocardiography has been the introduction of intravenous contrast agents for the optimization of echocardiographic imaging. This has proven to be of tremendous value, over and above the parallel improvement of equipment manufactured and new transducers capable of transmitting and receiving ultrasound at different frequencies. There are now clear recommendations by the American Society of Echocardiography jointly with the Europeans that regular use of intravenous contrast agents in echocardiography benefits image interpretation at rest and perhaps even more, during stress [1,2]. The symposium held during the Euroecho 8 congress in Athens, December 2004 on “Clinical value and perspectives of Contrast Echocardiography” gives us the opportunity to highlight the most important clinical implementations but also research opportunities ready to be implemented in clinical echocardiography today. There are now a number of second generation echo-contrast agents that have been in the market for several years all over the world and there are more to come very soon in the market, demonstrating the benefit of those agents. In the United States, Optison and Definity are routinely used to improve image quality. In Europe, Optison and Sonovue are used for the same indications. Several hundreds of thousands of patients have received echo-contrast todate and compared to other contrast agents used in imaging, echo contrast agents are the safest [3]. During that symposium, experts from all-over Europe presented their experience in considering current but also some future applications of contrast echocardiography. These new possibilities are clearly illustrated in the articles of this supplement from which some important remarks can be drawn. Image quality is crucial to formulate a diagnosis. Even experts can produce poor images and need to use contrast to improve quality. This is particularly important when other non-experts in echocardiography are looking at the pictures in order to make a clinical decision and if image quality is not convincing, then they will turn into alternative imaging modalities that may produce a better picture. One good picture is worth a thousand words! Using contrast echocardiography and thus improving endocardial delineation of the left ventricle, allows for a better and more reproducible assessment of left ventricular ejection fraction in such a way that is comparable to cardiac magnetic resonance imaging (CMR) with only a fraction of its cost. This has been elegantly demonstrated by Hoffmann et al who used Sonovue in 120 patients from several centers in order to determine the agreement of unenhanced and contrast-enhanced echocardiography against biplane cine-ventriculography and CMR [4]. They convincingly showed that contrast-enhanced echocardiography significantly improves inter-observer variability for the assessment of ejection fraction to a level obtained by CMR, while cine-ventriculography exhibits a large inter-observer variability [4]. Furthermore, assessing reCARDIOLOGY UPDATE 2006