P5B-5 Echogenic Liposomes in High-Frequency Ultrasound Imaging

The goal of this study is to estimate the acoustic properties of our self-made echogenic liposomes including effective working time, resonance frequency, nonlinear scattering and fragmentation using a 25-MHz high-frequency ultrasonic imaging system. Our self-made echogenic liposomes were also prepared based on the film hydration method and their average size was 1600 nm. We found that 0.3 mL buffer volume at 7 centigrade temperature mixing with dry 0.25 mg liposomes powder at 120 seconds vibration duration are the optimal conditions for ultrasound imaging. The effective working time of the echogenic liposomes was approximately 10 minutes. The resonance frequency range is from 7 to 11 MHz. As transmitting 10 MHz pulses, nonlinear scattering of echogenic liposomes can be observed and the inducing harmonic components intensities increase with increasing the acoustic pressure. Fragmentation phenomenon occurs in 10-cycle 2.25 MHz driven pulses with 0.15 MPa. Potential applications of the echogenic liposomes include the high-frequency nonlinear imaging in small animals and configured as targeted agents.