Numerical simulation of low-intensity focused ultrasound in brain for neuromodulation

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Low-intensity focused ultrasound (LIFU) could effectively modulate neurons at a target brain region within the ultrasound focal spot, which indicates a potential of ultrasound for therapy of neural disorder noninvasively. LIFU employs ultrasound intensity similar to or lower than that used by medical ultrasound imaging so that LIFU does not produce tissue damage or temperature increase. LIFU could localize ultrasound intensity at a desired brain location of a millimeter range of the focal spot with sub-millimetre resolution. Therefore, the target brain cells can be modulated with high specificity without affecting the surrounding neurons. However, it is challenge to predict the ultrasound focal spot location at the desired brain region because of complicated head geometry and structures. Magnetic resonance imaging (MRI) can be used to monitor the focal spot during ultrasound neuro-modulation, but MRI is expensive and may not be always available at the treatment site. Furthermore, it could be difficult to estimate accurately the amount of ultrasonic energy applied at the target region due to ultrasound attenuation within the complicated head structures. Objective of this research project is to develop a numerical simulation tool to understand and evaluate the LIFU beam profile and intensity distribution within the brain, which is crucial and urgently demanded to make this LIFU neuro-modulation technology available as a standard tool for research in cognitive and psychiatric disorders. The developed simulation tool will allow us to locate ultrasound focal spot with sub-millimetre resolution and to control the desired ultrasound energy applied at the target brain region precisely. This project provides neuroscientists and clinicians a new tool to understand and treat major depression with potential benefits for millions of Canadians and globally.