A Non-Invasive In-Vivo Tissue Bubble Detector Using Pulse-Heterodyne Acoustical Resonance Spectroscopy

Period of Performance: 11/01/1994 - 11/01/1996


Phase 2 SBIR

Recipient Firm

Marisys, Inc.
131 NW 43rd Street
Boca Raton, FL 33431
Principal Investigator

Research Topics


Development of safe and efficient procedures for humans working under hyperbaric conditions requires a thorough understanding of gas bubble dynamics. It is generally accepted that the presence of gas phases in critical tissues is the principal agent of decompression illness; yet there currently exists no reliable mechanism for direct experimental verification of tissue gas bubble formation and growth. Further research into the genesis, dynamics and management of decompression induced tissue gas bubbles would be greatly accelerated by the availability of instrumentation capable of assaying bubble populations within a volume of tissue in-vivo. In preliminary research sponsored by the U.S. Navy (NMR&DC SIBR N93-049 Phase I) a wide range of technologies which might be used as the basis for a tissue bubble detector were evaluated; including acoustical, radiographic and electromagnetic approaches. Of the physical mechanisms evaluated, an ultrasound technique based upon a relatively unstudied non-linear bubble resonance phenomenon was determined to have the best potential for measuring gas bubble sizes and discriminating against non-bubble artifacts. Development of an instrument which exploits this phenomenon is proposed. the bubble instrument will be based upon acoustical resonance spectroscopy using short, high frequency interrogation pulses to provide high spatial resolution. The primary Phase II research effort will be the determination of an optimal strategy for generating pumping and interrogation waveforms and for rocessing the signal returns. Following the initial research and as a part of Phase II, instruments meeting the operational requirements of the Naval Medical Research Institute will be developed and delivered to NMRI for use in ongoing research.