Further studies on ultrasonic contrast blood flowmetry

It was demonstrated in a previous work (see IEEE Ultras. Sym. Proc., vol.2, pp.907-910, 1989) that change in ultrasonic attenuation of a flowing fluid as a function of time following a bolus injection of a gaseous ultrasonic contrast agent can be used to derive mean flow rate based upon the indicator dilution principle and that flow profile can be estimated using a real-time B-scanner from images of the agent. Here, results are presented to show that ultrasonic contrast agents may also be useful for time domain blood flow estimation via cross-correlation or a dual-probe approach. Two different approaches of time domain contrast ultrasonic flowmetry were studied using a mock flow loop: (1) velocity estimation using an optical correlator from recorded video ultrasonic images, and (2) velocity estimation using a two-probe arrangement from cross correlation of RF signals. Both methods use bolus injection of a contrast agent upstream from the monitoring site