Ultrasound contrast agents approved for use in the United States consist of microbubbles of high-density, high–molecular-weight gasses (perflutren or sufur hexafluoride) encapsulated by protein, lipid, or polymer shells. These agents enhance the reflection of ultrasound waves, increasing the signal-to-noise ratio and improving visualization of the vasculature. Indications approved by the Food and Drug Administration (FDA) include echocardiography (perflutren protein-type a microspheres [Optison, GE Healthcare], perflutren lipid microspheres [Definity, Lantheus Medical Imaging, Inc], and sulfur hexafluoride lipid-type A microspheres [Lumason, Bracco Diagnostics]); as well as evaluation of liver masses in adults and pediatric patients, and vesicouretral reflux in pediatric patients (Lumason only). Clinical practice guidelines from the American Society of Echocardiography, the Intrasocietal Accreditation Commission, and many international organizations provide guidance for sonographers on indications and uses of contrast agents, developing institutional policies, and contrast safety. Ultrasound contrast agents have an excellent overall safety profile and a low risk of serious adverse events. FDA-mandated contraindications and warnings have evolved over the last decade as a number of large clinical studies have confirmed the effectiveness and safety of ultrasound contrast for a variety of applications. All approved ultrasound contrast agents carry a black-box warning regarding the risk of cardiopulmonary reactions, including fatalities, which have occurred uncommonly during or following administration. The risk of adverse reactions may be greater in patients with preexisting cardiopulmonary conditions. The most common adverse event associated with contrast is headache. Other potential safety and tolerability concerns include anaphylactic reactions, use in patients with cardiovascular shunts, back pain (especially in patients receiving Definity), and use in women who are pregnant or nursing. Contrast-enhanced ultrasound guidelines emphasize the importance of a multidisciplinary team approach in the successful implementation of injected contrast agents. Sonographers have a critical role in identifying the need for contrast during a particular ultrasound examination, as well as working with hospital administrators to develop policies for the safe and effective use of contrast agents in imaging.
After reading this article, the participant should be able to:
- Discuss characteristics, properties, and approved clinical uses of ultrasound contrast agents approved for use in the United States.
- Describe the current black-box warning for ultrasound contrast agents and explain how this warning has changed over the last decade.
- Recognize other key safety and tolerability concerns associated with the use of these agents in ultrasound imaging.
Categories: Ultrasound/Sonography, Radiation Safety/Protection