TY - JOUR
T1 - Signal Processing for Stable Cavitation Focused Ultrasound BBB Disruption Control
AU - Khan, Sonia
AU - Smith, Michael
AU - Youssef, Ibrahim
AU - Shah, Bhavya
AU - Chopra, Rajiv
AU - Curiel, Laura
N1 - Publisher Copyright:
© 2021 IEEE.
PY - 2021
Y1 - 2021
N2 - 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.
AB - 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.
KW - Blood-brain barrier (BBB)
KW - area under the curve (AUC)
KW - cavitation
KW - filtering
KW - focused ultrasound
KW - interpolation
KW - microbubbles
KW - subharmonic frequency
KW - windowing
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U2 - 10.1109/IUS52206.2021.9593526
DO - 10.1109/IUS52206.2021.9593526
M3 - Conference article
AN - SCOPUS:85122891123
SN - 1948-5719
JO - IEEE International Ultrasonics Symposium, IUS
JF - IEEE International Ultrasonics Symposium, IUS
T2 - 2021 IEEE International Ultrasonics Symposium, IUS 2021
Y2 - 11 September 2011 through 16 September 2011
ER -