In vivo droplet vaporization using diagnostic ultrasound-a potential method for occlusion therapy?

The experimental objective was to determine whether a transpulmonary droplet emulsion (90%30 /spl mu/m) which would be utilized to occlude the capillary bed of tissue. Gas bubbles can be made in vivo to potentially block capillaries, by acoustic droplet vaporization (ADV) of injected, superheated, dodecafluoropentane droplets. Droplets evaporate into gas bubbles when exposed to an acoustic field who's peak rarefactional pressure exceeds a well defined threshold. It has been found that I.A. as well as I.V. injections can be used to introduce the emulsion into the blood stream and subsequently perform ADV (using B- and M-mode on a clinical ultrasound scanner) at the target site. I.V. administration results in a lower gas bubble yield, possibly due to droplet filtering in the lung, dilution in the blood volume or other circulatory effects.