Signal Processing for Stable Cavitation Focused Ultrasound BBB Disruption Control

Sonia Khan, Michael Smith, Ibrahim Youssef, Bhavya Shah, Rajiv Chopra, Laura Curiel

Research output: Contribution to journalConference articlepeer-review

Abstract

This paper aims to improve the cavitation response spectrum by applying filtering and signal processing techniques to better monitor stable cavitation in an animal blood-brain barrier (BBB) system (RK50, FUS Instruments). The acoustic signals detected by a hydrophone contain a strong 1420 kHz fundamental capable of distorting the A/D output. A proposed low-pass passive analog filter, with 1 MHz cut-off frequency, suppressed this fundamental and improved the system's dynamics of self-calibration based on the subharmonic. Current stability measurement relies on calculating area under the curve (AUC) within a 300 Hz bandwidth centered at the subharmonic frequency, corresponding to few points with the available frequency resolution. Fourier interpolation combined with windowing was used to boost the points available when determining the AUC. This combination also revealed changes in the spectrum by uncovering side lobes around the subharmonic with useful information. This suggests exploiting a wider bandwidth than the standard 300 Hz when using the AUC metric to detect stable and inertial cavitation for improved accuracy and system reliability. This methodology was confirmed in animal experiment, where the fundamental frequency was at 1556 kHz, and the subharmonic was expected at 778 kHz.

Original languageEnglish (US)
JournalIEEE International Ultrasonics Symposium, IUS
DOIs
StatePublished - 2021
Event2021 IEEE International Ultrasonics Symposium, IUS 2021 - Virtual, Online, China
Duration: Sep 11 2011Sep 16 2011

Keywords

  • Blood-brain barrier (BBB)
  • area under the curve (AUC)
  • cavitation
  • filtering
  • focused ultrasound
  • interpolation
  • microbubbles
  • subharmonic frequency
  • windowing

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

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