Assessment of Cavitation From DEFINITY and DEFINITY RT

Area of Science:

• Ultrasound physics and bioeffects
• Medical imaging contrast agents
• Biomedical engineering

Background:

• Microbubbles are widely used as ultrasound contrast agents.
• Understanding microbubble behavior under therapeutic ultrasound is crucial for safety and efficacy.
• DEFINITY and DEFINITY RT are common ultrasound contrast agents with potentially different properties.

Purpose of the Study:

• To compare the size distributions of DEFINITY and DEFINITY RT microbubbles.
• To quantify the cavitation activity of DEFINITY and DEFINITY RT after infusion through a multi-sideport catheter.
• To assess microbubble behavior under simulated physiological conditions with therapeutic ultrasound.

Main Methods:

• Microbubble size distributions were measured using an impedance-based particle counter.
• Cavitation activity (stable and inertial) was quantified using passive cavitation imaging.
• Experiments were conducted in a flow phantom mimicking the human femoral vein at 1.5 MHz ultrasound frequency.

Main Results:

• DEFINITY RT exhibited a significantly higher microbubble number density post-infusion compared to non-expired DEFINITY.
• DEFINITY RT demonstrated greater stable and inertial cavitation doses than both expired and non-expired DEFINITY.
• Non-expired DEFINITY showed the least amount of cavitation activity.

Conclusions:

• DEFINITY RT microbubbles generate higher cavitation activity compared to DEFINITY.
• Microbubble formulation and number density are critical factors influencing cavitation.
• These findings have implications for the safe and effective use of ultrasound contrast agents in therapeutic applications.