Principles of Contrast Echocardiography

Contrast echocardiography is used for a variety of clinical applications including the delineation of endocardial borders to assess wall motion, enhancement of the blood pool to better appreciate intra-cavitary abnormalities such as thrombi and masses, and assessment of myocardial microvascular perfusion. Contrast echocardiography relies on the ultrasound detection of acoustically active nano- or microparticles that undergo cavitation in an ultrasound field. In their most common form, microbubble contrast agents are composed of a gas core containing a high molecular weight, low-solubility gases; and are encapsulated by lipid, albumin, or polymer shells which reduce gas diffusion and lower surface tension. This chapter describes key technical elements of clinical and research contrast echocardiography including: (1) microbubble composition and characteristics, (2) microbubble behavior in the vasculature and their interactions with native cells and plasma proteins, (3) unique acoustic properties of microbubbles and how they can be leveraged to specifically detect contrast signal during clinical ultrasound imaging, and (4) safety of microbubble contrast agents.