Bioeffects considerations for diagnostic ultrasound contrast agents.
Diagnostic ultrasound contrast agents have been developed for enhancing the echogenicity of blood and for delineating other structures of the body. Approved agents are suspensions of gas bodies (stabilized microbubbles), which have been designed for persistence in the circulation and strong echo return for imaging. The interaction of ultrasound pulses with these gas bodies is a form of acoustic cavitation, and they also may act as inertial cavitation nuclei. This interaction produces mechanical perturbation and a potential for bioeffects on nearby cells or tissues. In vitro, sonoporation and cell death occur at mechanical index (MI) values less than the inertial cavitation threshold. In vivo, bioeffects reported for MI values greater than 0.4 include microvascular leakage, petechiae, cardiomyocyte death, inflammatory cell infiltration, and premature ventricular contractions and are accompanied by gas body destruction within the capillary bed. Bioeffects for MIs of 1.9 or less have been reported in skeletal muscle, fat, myocardium, kidney, liver, and intestine. Therapeutic applications that rely on these bioeffects include targeted drug delivery to the interstitium and DNA transfer into cells for gene therapy. Bioeffects of contrast-aided diagnostic ultrasound happen on a microscopic scale, and their importance in the clinical setting remains uncertain.
Miller
Douglas L
DL
Department of Radiology, University of Michigan, Ann Arbor, MI 48109-0553, USA. douglm@umich.edu
Averkiou
Michalakis A
MA
Brayman
Andrew A
AA
Everbach
E Carr
EC
Holland
Christy K
CK
Wible
James H
JH
Wu
Junru
J
D000818:Animals; D001831:Body Temperature; D003287:Contrast Media / Q000009:adverse effects*; D004452:Echocardiography; D005740:Gases / Q000378:metabolism; D006801:Humans; D012449:Safety; D014463:Ultrasonography
D003287:Contrast Media; D005740:Gases