Detecting HIFU-induced inertial cavitation in both space and time with a diagnostic ultrasound system

Presented by Caleb Farney

ABSTRACT
The onset and presence of inertial cavitation in high-intensity focused ultrasound (HIFU) therapy has been identified as an important indicator of energy deposition for therapy guidance. A common technique for detecting inertial cavitation is so-called passive cavitation detection, where broad band noise emissions indicative of inertially-driven bubble collapses are detected using a fixed focus acoustic transducer. This technique is sub-optimal for clinical applications, for most passive cavitation detector (PCD) transducers are tightly focused and thus afford limited spatial coverage of the HIFU focal region. Here we report on efforts to use a Terason 2000 diagnostic ultrasound system as a PCD by operating in passive mode, obtaining the RF signals corresponding to each scan line, and filtering out the contribution from scattering of the main HIFU signal and its harmonics. This approach allows for spatially-resolved detection of inertial cavitation throughout t! he focal region while being insensitive to scattering from voids or bubbles. Incorporation of these techniques in a diagnostic ultrasound platform could result in a much-needed tool for improving HIFU guidance and treatment. [Work supported by the Dept.
of the Army (Award No. DAMD17-02-2-0014) and the Center for Subsurface Sensing and Imaging Systems (NSF ERC Award No. EEC-9986821).]