Characterization of Acoustic Properties of PVA-Shelled Ultrasound Contrast Agents
This work examines the acoustic behavior of ultrasound contrast agents made of poly (vinyl alcohol) (PVA) shelled microbubbles manufactured at three different pH and temperature conditions. Backscattering amplitude, attenuation coefficient and phase velocity of ultrasonic waves propagating through suspensions of PVA contrast agents were measured at temperature values ranging from 24°C to 37°C in a frequency range from 3 MHz to 13 MHz. A significant enhancement of the backscattering amplitude and a weak dependence on temperature were observed. Attenuation and phase velocity, on the other hand, showed higher sensitivity to temperature variations. The dependence on system parameters such as the number of cycles, frequency, and exposure of the peak negative pressure, P thr , at which ultrasound contrast agents fracture was also investigated. The effects of temperature, blood, and, whenever data were available, of the dimension of the microbubbles on P thr are also considered. The large shell thickness notwithstanding, the results of this investigation show that at room temperature, PVA contrast agents fracture at negative peak pressure values within the recommended safety limit. Furthermore, P thr decreases with increasing temperature, radius of the microbubbles, and number of cycles of the incident wave. In conclusion, these results suggest that PVA-shelled microbubbles may offer a potentially viable system to be employed for both imaging and therapeutic purposes.
KeywordsContrast Agent Phase Velocity Ultrasonic Wave Acoustic Property Pulse Repetition Frequency
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- 4.Grishenkov D, Pecorari C, Brismar TB and Paradossi G (2009) Characterization of acoustic properties of PVA-shelled ultrasound contrast agents: linear properties (Part I). Ultrasound Med Biol. In printGoogle Scholar