Influence of contrast-enhanced ultrasound administration setups on microbubble enhancement: a focus on pediatric applications.

BACKGROUND: In pediatrics, contrast-enhanced ultrasound offers high-quality imaging with an excellent safety profile.

OBJECTIVE: To investigate the effects of varying intravenous administration setups on in vitro enhancement and concentration of two commercially available ultrasound contrast agents, taking into consideration potential pediatric applications.

MATERIALS AND METHODS: We quantified in vitro enhancement using a flow phantom (ATS Laboratories, Bridgeport, CT) and Acuson S3000 ultrasound system (Siemens Healthineers, Mountain View, CA) with a 9L4 probe in Cadence pulse sequencing mode. We determined microbubble concentration with an LSRII flow cytometer (BD Biosciences, San Jose, CA). We investigated Optison (GE Healthcare, Princeton, NJ) and Lumason (Bracco, Geneva, Switzerland) ultrasound contrast agents. The ultrasound (US) contrast agent was injected via a 1 mL syringe and flushed with 5 mL of saline through a 22-gauge diffusion catheter (BD Medical, Franklin Lakes, NJ) with the following variations: in-line injection through a 3-way stopcock with and without a neutral displacement connector (ICU Medical, San Clemente, CA), perpendicular through a 3-way stopcock with and without a connector, and without a 3-way stopcock. We also conducted injections through a 22-gauge standard angiocatheter.

RESULTS: Injection through the connector and perpendicular injection via the 3-way stopcock resulted in significant decreases in enhancement for both ultrasound contrast agents (P<0.0001). Injection through the connector resulted in significant decrease in concentration for Optison (P<0.05). Neither addition of the 3-way stopcock (P>0.24) nor use of a pediatric diffusion catheter (P>0.28) affected the enhancement.

CONCLUSION: Ultrasound contrast agent enhancement depends on the administration route, although some effects appear to be specific to the ultrasound contrast agent used. To avoid loss of enhancement, neutral displacement connectors and perpendicular injection should be avoided.