Administration of a contrast agent to a patient will increase the amount of information that can be obtained from any method of diagnostic imaging. Iodinated contrast agents, barium sulfate, and gadolinium are routinely used for radiography, CT, and MRI in both human and animal patients. Although administration of any contrast agent may be associated with the development of adverse events, the benefits of administration are usually considered to exceed the risk.1–7 In veterinary medicine, the use of CEUS is not as common as the use of other contrast-enhanced imaging techniques. Contrast agents for ultrasonography consist of microbubbles with a size approximately equal to that of an RBC. These microbubbles typically contain a high-molecular weight gas core that is encapsulated in a lipid or polymer shell. The gas core makes the microbubble extremely echogenic such that individual bubbles can be detected ultrasonographically.8 The microbubbles remain strictly within the vasculature and are used to highlight blood flow and tissue perfusion. The use of CEUS does not involve ionizing radiation and is not associated with nephrotoxicosis; therefore, it is commonly used in human patients in Europe and Asia.9,10 In the United States, the FDA has not approved microbubble contrast agents for use in diagnostic imaging procedures except for cardiac imaging in people. In 2007, the FDA announced a black box warning for all ultrasonographic contrast agents following the death of 4 patients after injection of a microbubble contrast agent, although none of those deaths was proven to have been caused by injection of the contrast agent.11 Since then, results of large, multicenter studies12,13 indicate that CEUS is a safe diagnostic imaging method for human patients.
Ultrasonography is the most common cross-sectional diagnostic imaging method used in dogs and cats because it is readily available and does not require animals to be anesthetized. Results of multiple studies14–18 in which CEUS was used in dogs and cats suggest that CEUS is a clinically valuable diagnostic procedure, and no adverse events associated with injection of various contrast agents were reported. However, the true incidence of adverse events associated with CEUS is unknown. Accurate information about potential adverse events associated with CEUS in dogs and cats is important for the education of pet owners and referring veterinarians. The purpose of the study reported here was to perform a retrospective multicenter survey to determine the incidence of adverse events within 24 hours after CEUS in dogs and cats and to calculate the risk for death within 24 hours after ultrasonography for dogs and cats that had CEUS performed, compared with that for dogs and cats that had ultrasonography performed without injection of a contrast agent. We hypothesized that the incidence of adverse events within 24 hours after CEUS would be low and that the risk of death in dogs and cats within 24 hours after CEUS would not differ from that in dogs and cats with similar clinical signs that had ultrasonography performed without injection of a contrast agent.
SAS, version 9.2, SAS Institute Inc, Cary, NC.
Definity, Lantheus Medical Imaging, North Billerica, Mass.
Levovist, Schering, Berlin, Germany.
Optison, GE Healthcare, Princeton, NJ.
Sonovue, Bracco Diagnostics Inc, Princeton, NJ.
Targestar-P, Targeson Inc, San Diego, Calif.
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