Impact of hydrostatic pressure on phase-change contrast agent activation by pulsed ultrasound

Saurabh Raut, Mawia Khairalseed, Arvin Honari, Shashank R. Sirsi, Kenneth Hoyt

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


A phase-change contrast agent (PCCA) can be activated from a liquid (nanodroplet) state using pulsed ultrasound (US) energy to form a larger highly echogenic microbubble (MB). PCCA activation is dependent on the ambient pressure of the surrounding media, so any increase in hydrostatic pressure demands higher US energies to phase transition. In this paper, the authors explore this basic relationship as a potential direction for noninvasive pressure measurement and foundation of a unique technology the authors are developing termed tumor interstitial pressure estimation using ultrasound (TIPE-US). TIPE-US was developed using a programmable US research scanner. A custom scan sequence interleaved pulsed US transmissions for both PCCA activation and detection. An automated US pressure sweep was applied, and US images were acquired at each increment. Various hydrostatic pressures were applied to PCCA samples. Pressurized samples were imaged using the TIPE-US system. The activation threshold required to convert PCCA from the liquid to gaseous state was recorded for various US and PCCA conditions. Given the relationship between the hydrostatic pressure applied to the PCCA and US energy needed for activation, phase transition can be used as a surrogate of hydrostatic pressure. Consistent with theoretical predictions, the PCCA activation threshold was lowered with increasing sample temperature and by decreasing the frequency of US exposure, but it was not impacted by PCCA concentration.

Original languageEnglish (US)
Pages (from-to)3457-3466
Number of pages10
JournalJournal of the Acoustical Society of America
Issue number6
StatePublished - Jun 1 2019

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Acoustics and Ultrasonics


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