Quantitative acoustic characterization of a new surfactant-based ultrasound contrast agent.
The acoustic properties of a new ultrasound contrast agent, ST68, have been investigated. ST68 is a sonicated mixture of nonionic surfactants (Span-type and Tween-type) consisting of stabilized microbubbles with a mean diameter of 3.8 microns and a concentrations of 7.1 x 10(8) bubbles/mL. A pulsatile flow system was used to acquire data in vitro. The acoustic properties of ST68, as a function of time, frequency and dose, were calculated. Enhancement changed nonlinearly with contrast agent dose; maximum was 13.1 dB +/- 1.0 dB for a dose of 0.30 microL/mL of suspending medium. Attenuation reached approximately 11 dB/cm for dosages above 0.27 microL/mL and for frequencies between 2.5 and 6.0 MHz. In vivo, i.v. injections of ST68 were given to 4 rabbits (doses from 0.01 to 0.23 mL/kg). A clear increase in flow signal intensity was observed for 1 to 2 min. An in vivo dose-response curve was calculated from audio Doppler signals obtained with a 10-MHz cuff transducer placed around the distal aorta. Maximum enhancement was 18.3 dB +/- 3.13 dB for a 0.13 mL/kg dose. Moreover, ST68 appears to follow a simple relationship between in vivo enhancement and dose. In conclusion, ST68 is capable of producing marked vascular enhancement. Its acoustic properties have been characterized in vitro and in vivo.
Forsberg
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F
Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA. forsberg@esther.rad.tju.edu
Wu
Y
Y
Makin
I R
IR
Wang
W
W
Wheatley
M A
MA
D000162:Acoustics; D000818:Animals; D003287:Contrast Media; D006601:Hexoses; D007668:Kidney / Q000000981:diagnostic imaging; D011136:Polysorbates; D011673:Pulsatile Flow; D011817:Rabbits; D013501:Surface-Active Agents; D018615:Ultrasonography, Doppler, Color / Q000379:methods*
D003287:Contrast Media; D006601:Hexoses; D011136:Polysorbates; D013501:Surface-Active Agents; C009298:sorbitan monostearate