Objective
Single-element low-intensity focused ultrasound (LIFU) is an emerging form of human
neuromodulation. Current coupling methods are impractical for clinical bedside use.
Here, we evaluate commercially available high-viscosity gel polymer matrices as couplants
for human LIFU neuromodulation applications.
Methods
We first empirically tested the acoustic transmission of three densities at 500 kHz
and then subjected the gel with the least acoustic attenuation to further tests of
the effect of thickness, frequency, de-gassing and production variability.
Results
The highest-density gel had the lowest acoustic attenuation (3.3%) with low lateral
(<0.5 mm) and axial (<2 mm) beam distortion. Different thicknesses of the gel up to
10 mm did not appreciably affect results. The gel polymers exhibited frequency-dependent
attenuation at 1 and 3 MHz up to 86.6%, as well as significant beam distortion >4
mm. Poor de-gassing methods also increased pressure attenuation at 500 kHz up to 59.6%.
Standardized methods of making these gels should be established to reduce variability.
Conclusion
Commercially available de-gassed, high-density gel matrices are a low-cost, easily
malleable, low-attenuation and distortion medium for the coupling of single-element
LIFU transducers for human neuromodulation applications at 500 kHz.
Keywords
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Article info
Publication history
Published online: March 06, 2023
Accepted:
February 7,
2023
Received in revised form:
January 19,
2023
Received:
October 24,
2022
Publication stage
In Press Corrected ProofIdentification
Copyright
© 2023 World Federation for Ultrasound in Medicine & Biology. All rights reserved.
