Optimal phase on biaxial driven transducers based only on electrical power measurements

Delgado, Sagid; Curiel, Laura; Rubel, Oleg; Silva, Geovane Da; Pichardo, Samuel

doi:10.1109/ultsym.2017.8092099

Cited by 1 publication

(1 citation statement)

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“…This ring-type biaxial transducer presents opportunities for addressing steering and efficiency issues with a smaller footprint for a new generation of fully steerable phased arrays. The dimensions of biaxial transducers achieved to date make them particularly suitable as single elements for small animal studies, or for assembly into an array format for clinical applications (Pichardo et al 2015, Delgado et al 2017, 2021.…”

Section: Introductionmentioning

confidence: 99%

Biaxial ultrasound driving technique for small animal blood–brain barrier opening

Pellow,

Li,

Delgado

et al. 2023

Phys. Med. Biol.

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Biaxial driving can more efficiently convert electrical power to forward acoustic power in piezoelectric materials, and the interaction between the orthogonal electric fields can produce a combination of extensional and shear deformations as a function of the phase difference between them to allow dynamic steering of the beam with a single-element. In this study, we demonstrate for the first time the application of a single-element biaxially driven ring transducer in vivo for blood–brain barrier opening in mice, and compare it to that achieved with a conventional single-element highly focused (F# = 0.7) spherical transducer operating at a similar frequency. Transcranial focused ultrasound (0.45 MPa, 10 ms pulse length, 1 Hz repetition frequency, 30 s duration) was applied bilaterally to mice with a 40 μl/kg bolus of DefinityTM microbubbles, employing either a single-element biaxial ring (1.482 MHz, 10 mm inner diameter, 13.75 mm outer diameter) or spherical (1.5 MHz, 35 mm diameter, F# = 0.7; RK50, FUS Instruments) transducer on each side. Follow-up MRI scans (T1 pre- and post- 0.2 mmol/kg Gd injection, T2) were acquired to assess blood–brain barrier opening volume and potential damage. Compared to blood–brain barrier opening achieved with a conventional single-element spherical focused transducer, the opening volume achieved with a single-element biaxial ring transducer was 35% smaller (p = 0.002) with a device of a ring diameter of 40% the aperture size. Axial refocusing was further demonstrated with the single-element biaxial ring transducer, yielding a 1.63 mm deeper, five-fold larger opening volume (p = 0.048) relative to its small-focus mode. The biaxial ring transducer achieved a more localized opening compared to the spherical focused transducer under the same parameters, and further enabled dynamic axial refocusing with a single-element transducer with a smaller fabrication footprint.

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Section: Introductionmentioning

confidence: 99%