Direct video-microscopic observation of the dynamic effects of medical ultrasound on ultrasound contrast microspheres.
OBJECTIVE
Ultrasound can cause destruction of microbubble contrast agents used to enhance medical ultrasound imaging. This study sought to characterize the dynamics of this interaction by direct visual observation of microbubbles during insonification in vitro by a medical ultrasound imaging system.


METHODS
Video microscopy was used to observe air-filled sonicated albumin microspheres adsorbed to a solid support during insonation.


RESULTS
Deflation was not observed at lowest transmit power settings. At higher intensities, gas left the microparticle gradually, apparently dissolving into the surrounding medium. Deflation was slower for higher microsphere surface densities. Intermittent ultrasound imaging (0.5 Hz refresh rate) caused slower deflation than continuous imaging (33 Hz).


CONCLUSIONS
Higher concentrations of microbubbles, lower ultrasound transmit power settings, and intermittent imaging each can reduce the rate of destruction of microspheres resulting from medical ultrasound insonation.
Klibanov
A L
AL
Mallinckrodt Inc., St. Louis MO 63134, USA. Sasha.L.Klibanov@mkg.com
Ferrara
K W
KW
Hughes
M S
MS
Wible
J H
JH
Wojdyla
J K
JK
Dayton
P A
PA
Morgan
K E
KE
Brandenburger
G H
GH
D000327:Adsorption; D000418:Albumins / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D006801:Humans; D016014:Linear Models; D018715:Microscopy, Video / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D008863:Microspheres; D013997:Time Factors; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data
D000418:Albumins; C060687:Albunex; D003287:Contrast Media