The 176th Meeting of the Acoustical Society of America (ASA) was held November 5–9, 2018, in Victoria, British Columbia, Canada. With an overall mission to generate, disseminate, and promote the knowledge and practical applications of acoustics, the meeting included several presentations of interest to the focused ultrasound community. Researchers from the Focused Ultrasound Foundation were invited to present their recent simulation study that developed and validated algorithms for how ultrasound propagates through the skull. Additional topics in the program included blood—spinal cord barrier opening, blood-brain barrier opening, droplet vaporization for mechanical brain tissue ablation, additional simulation work, and much more.
Blood–Spinal Cord Barrier (BSCB) Opening. Several papers from the University of Toronto/Sunnybrook Research Institute addressed BSCB opening. They described preclinical work, modeling, and the design of a transducer prototype for BSCB opening within human vertebrae. Their technique looks to be effective in preclinical experiments, and further technological development is ongoing to scale the transducers for human use.
Blood-Brain Barrier (BBB) Opening. Dr. Mark Borden (Boulder) presented data suggesting that the gas volume of injected microbubbles is the unifying parameter in microbubble dosing for BBB opening. O. Vince (PhD student with Dr. Eleanor Stride, Oxford, UK) presented preclinical work on the use of targeted magnetic nanodroplets for BBB opening. This is the first proof of concept study, and her preclinical study is ongoing.
Droplet Vaporization for Mechanical Brain Tissue Ablation. Drs. Tyrone Porter (Boston University) and Nathan McDannold (Harvard/Brigham and Women’s) are investigating mechanical (cavitation/non-thermal) ablation of brain tumors with phase-shift nanodroplets. This preclinical work is centered on developing safe and effective treatment regimens. It uses low frequency focused ultrasound that is close to the 220kHz range of the ExAblate system.
Simulation of Acoustic Propagation through Bone. L. Richards (PhD student with Dr. Robin Cleveland, Oxford, UK) presented neuromodulation simulations using k-waves to simulate propagation through human skull from a single element focused transducer. Experiments on volunteers are ongoing. Researchers at the University of Toronto presented a ray tracing method to simulate propagation through human vertebrae with phased array. The group from the Focused Ultrasound Foundation shared an invited presentation on their work simulating propagation through skull using experimental data to validate the algorithms.
Meeting report submitted by Frédéric Padilla, PhD, Foundation Research Fellow.