Acoustic Coupling Pads for the Control of Ultrasound Neuromodulation Exposure
Thursday, June 1, 2023
3:30 PM-5:30 PM
BIOMED Master's Thesis Defense
Title:
Acoustic Coupling Pads for the Control of Ultrasound Neuromodulation Exposure
Speaker:
Samantha F. Schafer, Master's Candidate
School of Biomedical Engineering, Science and Health Systems
Drexel University
Advisor:
Peter A. Lewin, PhD
Richard B. Beard Distinguished University Professor
School of Biomedical Engineering, Science and Health Systems
Drexel University
Details:
The purpose of this work is to develop an experimental system that would control acoustic artifacts when evaluating the clinical outcome of the noninvasive, ultrasound administered neurostimulation. Such systems are needed to ensure the statistical significance of the results and determine the efficacy obtained when performing single- and double-blind studies. Focused ultrasound administered at low intensities (below ISPTA = 720 mW/cm2) and frequencies in the range 500 kHz – 750kHz has been reported to treat conditions like anxiety, depression, and other psychiatric disorders. However, the assessment of clinical efficacy and significance of the outcome requires these experiments to be performed as single- or (ideally) double-blind studies, to substantiate statistical results. This is challenging because when energized to release an acoustic pulse, ultrasound transducers generate an audible clicking sound associated with the pulse repetition frequency of the treatment protocol, thereby producing an auditory cue, and hence unfavorably interfering with the design of the study.
To bypass this issue an experimental approach able to control ultrasound exposure while maintaining this auditory cue to is needed; it would have to ensure that the subjects (both sham and treated) are single blinded to the exposure condition, and simultaneously prevent the operators from inadvertently providing cues to the subject (double-blinding). Prior methods mentioned in the literature, such as disrupting the mechanical coupling between the transducer and the patient or using an “on/off” protocol, do not solve this problem.
Accordingly, this research focused on an innovative approach of developing acoustic coupling pads that facilitated single-blind and double-blind experiments by selectively transmitting ultrasound into the subject without affecting the audible sound or sensations from the neurostimulation transducer. The pads developed successfully provided a blinding method to low intensity focused ultrasound neuromodulation; the testing of both transmitting and absorbing pads indicated negligible transmission loss of about 5% and acoustic pressure amplitude attenuation of about 40 dB (100 times), respectively.
Contact Information
Natalia Broz
njb33@drexel.edu