Steering Capabilities of an Acoustic Lens for Transcranial Therapy: Numerical and Experimental Studies

Abstract

Brain therapy by transcranial focused ultrasound needs to compensate for the delays locally induced by the skull. The patient-specific phase profile is currently generated by a multi-element array with a growing number of elements. We recently introduced a disruptive approach, consisting in using a single element transducer coupled to an acoustic lens of controlled thickness: by adjusting the local thickness of the lens, we were able to induce a phase difference which compensated that of the skull. Nevertheless, such an approach suffers from an apparent limitation: the lens is a priori designed for one specific target. In this paper, we demonstrate the possibility of taking advantage of the isoplanatic angle of the aberrating skull in order to steer the focus by mechanically moving the transducer/acoustic lens pair around its initial focusing position. This study, conducted on three human skull samples, confirms that tilting of the transducer with the lens restores a single focus at 914 kHz for a steering up to 11mm in the transverse direction, and 10mm in the longitudinal direction, around the initial focal region. Acoustic lens, transcranial ultrasound, therapeutic ultrasound

Sonication of the anterior thalamus with MRI-Guided transcranial focused ultrasound (tFUS) alters pain thresholds in healthy adults: A double-blind, sham-controlled study

“…However, deviations in subject skull surface may perturb the sonication beam trajectory in configurations. Some groups have proposed using 3D printed lenses to account for skull curvature and these likely can correct for inconsistencies[ 48 , 49 ].…”

“…proposed using 3D printed lenses to account for skull curvature and these likely can correct for inconsistencies [48,49].…”

Neuronavigated Repetitive Transcranial Ultrasound Stimulation Induces Long-Lasting and Reversible Effects on Oculomotor Performance in Non-human Primates

“…For frequencies higher than 300 kHz, CT-based (Marquet et al, 2009;Pulkkinen et al, 2014) or MR-based (Wintermark et al, 2014;Miller et al, 2015) aberration correction needs to be performed. This can be achieved with multielement arrays of transducers (Jeanmonod et al, 2012;Chauvet et al, 2015) or with single element transducers combined with an acoustic lens (Maimbourg et al, 2018a(Maimbourg et al, , 2019. With these latest developments, rTUS appears to be very promising and offers a novel and competitive neurostimulation technique.…”

Direct Communication Between Brains: A Systematic PRISMA Review of Brain-To-Brain Interface

“…However, in this case, it is hard to adjust the directivity and focal depth of ultrasound beam, which is a limitation of tFUS CBI systems to target specific areas inside the brain from the hardware perspective. To overcome such limitations, some promising methods have been proposed recently, which includes applying acoustic lens (Maimbourg et al, 2020) or holographic plates (Jiménez-Gambín et al, 2019) in front of the tFUS transducer to achieve adjustable acoustic beam steering and focusing. Furthermore, new applications of tFUS based CBI systems may be explored more.…”