Applications of Ultrasound Contrast Agents

Echocardiography plays a critical role in the management of patients, especially in its ability to evaluate left ventricular (LV) global and regional function. Its clinical utility, however, may be affected by image quality. In approximately 10% to 15% of routine echocardiograms and up to 25% to 30% of studies performed in intensive care units, the endocardial border is not clearly defined. Ultrasound contrast agents have been shown in numerous studies to enhance delineation of the endocardial border, which improves both the qualitative and quantitative assessment of LV function and decreases interobserver and intraobserver variability.

Several ultrasound-enhancing agents (UEAs) are currently available for clinical use, which are listed in previous chapters. They are approved by regulatory agencies in multiple countries for left ventricular opacification (LVO), which enhances definition of LV endocardial borders in patients with “technically suboptimal” echocardiograms at rest. Some of the agents are also approved for enhancement of Doppler signals. Apart from helping to improve assessment of LV systolic function, ultrasound contrast agents have been shown to enhance the detection and evaluation of other structural abnormalities. This chapter provides examples of common scenarios in which ultrasound contrast agents can provide better delineation of not only cardiac function but also pathology. Not all current clinical applications can be reviewed within the scope of this chapter, and for more details, readers are referred to the most recent consensus statement about contrast agents released by the American Society of Echocardiography.