Internship: Transcranial ultrasound stimulation with acoustic lens

The Institute Physics for Medicine Paris develops transcranial focused ultrasound therapy systems. In particular, the team is a pioneer in the modulation of nerve activity (neuromodulation) using low-intensity focused ultrasound. Neuromodulation is a major tool in physiology and medicine, for the study of brain mechanisms and the treatment of numerous neurological diseases. Various techniques have been introduced to improve precision (deep brain stimulation, optogenetics), or to offer a non-invasive approach (transcranial electrical stimulation (TES), transcranial magnetic stimulation (TMS)). Transcranial Ultrasound has the unique potential to perform not only cortical but also deep neurostimulation, with millimetric resolution, and to do so non-invasively. During this internship, the student will participate in the development of a non-invasive, low-cost transcranial focused ultrasound device, based on a unique technology recently patented by our laboratory: an acoustic lens manufactured by 3D printing and placed in front of an ultrasound mono-element, in order to correct aberrations due to the skull [1]. The great heterogeneity of the skull defocuses and alters the quality of an ultrasound beam passing through it. The laboratory benefits from 20 years’ experience in transcranial ultrasound focusing [2].

The current version of the device incorporates a focused ultrasound transducer with characteristics optimized to reach a given therapeutic target, being studied in an ongoing clinical trial. The internship will focus on exploring new transducer characteristics for other therapeutic targets.

The internship will be divided into two parts:

– the student will search and exploit CT and MRI image banks (public or private) to obtain information representative of the broadest possible population. The student will identify anatomical targets of interest and develop an automatic method for planning (including probe positioning) neuromodulation treatment on these targets.

– the student will set up numerical simulations of ultrasound propagation through the skull [3] to assess the impact of candidate transducer parameters (radius of curvature, diameter, frequency, etc.) on the safety and efficacy of treatments for each therapeutic target.

If the results are satisfactory, this new probe could be used in clinical trials by 2026.

[1] Maimbourg G. et al. 3D-printed adaptive acoustic lens as a disruptive technology for transcranial ultrasound therapy using single-element transducers. https://doi.org/10.1088/1361-6560/aaa037
[2] Aubry J-F. et al.. Optimal focusing by spatio-temporal inverse filter. II. Experiments. Application to focusing through absorbing and reverberating media.  https://doi.org/10.1121/1.1377052
[3] http://www.k-wave.org