Using an Ultrasonic Instrument to Size Extravascular Bubbles

In an ongoing development project, microscopic bubbles in extravascular tissue in a human body will be detected by use of an enhanced version of the apparatus described in "Ultrasonic Bubble- Sizing Instrument" (MSC-22980), NASA Tech Briefs, Vol.24, No.10 (October 2000), page 62. To recapitulate: The physical basis of the instrument is the use of ultrasound to excite and measure the resonant behavior (oscillatory ex- pansion and contraction) of bubbles. The resonant behavior is a function of the bubble diameter; the instrument exploits the diameter dependence of the resonance frequency and the general nonlinearity of the ultrasonic response of bubbles to detect bubbles and potentially measure their diameters.