Hologram-assisted focused ultrasound for brain therapy

Acoustic holograms are 3-D-printed structures that can passively modulate the transmitted wavefront from a single-element source and generate arbitrary-shape beams in multi-layered media. This approach has been of great interest in the brain therapy field, where the skull-induced beam aberration leads to undesired off-targeting effects while the complex brain anatomy may limit optimal target coverage. Acoustic holograms have been shown to successfully address these limitations by providing a more simple and cost-efficient alternative as compared to phased arrays. This presentation will cover assessment of acoustic holograms in both animal and human applications, including hologram design technical details. First, an overview of potentially useful acoustic patterns generated transcranially for brain applications will be presented. Second, the basics of hologram design are described, with different approaches of wavefront processing and heights distribution generation depending on single-element transducer geometry. Third, an overview of the preclinical blood–brain barrier (BBB) opening and neuromodulation outcomes in mice will be presented, followed by BBB opening outcomes in non-human primates. Finally, in-silico feasibility of clinical BBB opening and neuromodulation will be reported. Hologram-assisted focused ultrasound (FUS) is a promising and powerful technology which provides new avenues into a novel and simple approach for cost-efficient and rapid FUS application in the brain.