ABSTRACT
Objective: To analyze contrast imaging characteristic and resistance to acoustic pressure of perfluorooctylbromide (PFOB) lipidic microbubbles and compared with perfluoropropane (C3F8) lipidic microbubbles in vitro. Methods: PFOB lipidic particles with biotin and C3F8 lipidic microbubbles with biotin were prepared, and the stability of them were evaluated. Then the agents were used for imaging before and after adding of avidin, and the signal intensity were compared. Both PFOB particles and C3F8 microbubbles were exposed in ultrasound field of low (MI=0.28) and high (MI=0.56) ultrasound pressure levels. Their signal intensity after different exposure time (10, 20, 30 s) were compared. Results: Aggregation occurred in both two contrast agents after addition of avidin,and the particle sizes were significantly larger before (both P<0.05). The differences of particle size between the two contrast agents were significant before (t=16.225, P<0.001) and after addition of avidin (t=-5.046,P<0.001). The concentration of PFOB lipid particles did not change significantly during the observation period of stability evaluation, while C3F8 microbubbles decreased with standing time. Addition of avidin produced significant imaging enhancement in PFOB particles. However, C3F8 microbubbles manifested ultrasonic backscatter before and after adding of avidin. The signal intensity of PFOB particles were stable under low (MI=0.28) and high acoustic pressure (MI=0.56). The signal intensity of C3F8 microbubbles decreased with the prolongation of exposure time under low (MI=0.28) and high acoustic pressure (MI=0.56). Conclusion: Compared with C3F8microbubbles, PFOB particles with smaller particle size and better resistance to acoustic pressure, more suitable for targeted contrast ultrasound imaging.