Different microbubble ultrasound contrast agents have
been approved for abdominal and cardiac applications,
and their use has increased over recent years. Experimental
studies with high power ultrasound beams have
shown that microbubbles produce bioeffects in the cells
of nearby tissues as a result of cavitation. To prevent
these effects, the power of the ultrasound beam should be
kept below the cavitation threshold. Clinically, most
adverse reactions result in minor, self-resolving events
such as headache, nausea, altered taste, and a sensation
of heat. Anaphylactoid reactions, however, may rarely
occur and usually resolve spontaneously or with symptomatic
treatment. In a few cases anaphylactoid reactions
may be severe, or even fatal. Despite this, microbubble
contrast agents are safe by any reasonable standard, and
certainly are safe compared to iodine- and gadolinium based
contrast agents.
