ASA 125th Meeting Ottawa 1993 May

3pPA3. The role of acoustic radiation force in contrast enhancement techniques using bubble-based ultrasound contrast agents.

J. B. Fowlkes

E. A. Gardner

J. A. Ivey

P. L. Carson

Dept. of Radiol., Univ. of Michigan, Ann Arbor, MI 48109-0553

The movement of bubbles in an acoustic field has recently been used to manipulate bubbles for the purpose of contrast enhancement in medical applications. Some ultrasound contrast agents consist of stabilized microbubbles which, when exposed to an acoustic field, can be collected at specific points in space and may be moved by translating the field. One application for this type of bubble manipulation is the collection of bubbles within the urinary tract for urinary reflux diagnosis. Experiments conducted on sacrificed dogs indicate that bubbles can be moved in a controlled fashion within the bladder using external acoustic fields. In addition, acoustic radiation force could be used to overcome hydrodynamic forces in flowing blood. Bubbles could be pushed to a vessel wall to collect contrast and when the sound field was turned off, a bolus of contrast agent would reenter the flow for measurement of tissue perfusion. In preliminary experiments, a bolus of bubbles was created in blood flowing through dialysis tubing. This paper will review these experimental findings and present an examination of the mechanisms involved in each application. [Work supported in part by USPHS Grant No. DK-42290.]