TRANSCUTANEOUS INTERRUPTION OF ULTRASOUND CONTRAST AGENTS FOR BLOOD-FLOW EVALUATION

RATIONALE AND OBJECTIVES. The ability to create short boluses in targe ted arteries with rapid rise times is limited by the transport of bubb les from the venous to arterial portion of the circulation. Acoustic i nterruption of contrast agent in arteries may create the short boluses necessary for simple wash-in/wash-out measures of blood flow. METHODS . An ultrasound contrast agent was used with spectral Doppler ultrasou nd to observe contrast interruption in femoral arteries and VX2 carcin oma in a rabbit model. At an upstream location in the femoral artery, single, sinusoidal ultrasound tone bursts at 1.8 MHz with durations of 0.25 to 1 seconds were applied to interrupt the flow of contrast agen t injected intravenously, RESULTS. In VX2 carcinoma, bursts as short a s 40 cycles produced contrast interruption lasting only one cardiac cy cle within the tumor periphery and I-SPPA <3 W/cm(2) produced measurab le interruptions. CONCLUSIONS. Acoustic fields applied transcutaneousl y interrupted flow of contrast agents to form temporally short negativ e boluses.