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Investigation of Transcranial Focused Ultrasound Attenuation with Multilayer Head Model

Focused ultrasound is potential for brain imaging and neuromodulation, with high spatial resolution. Most focused ultrasound applications in brain science are based on the ultrasonic characteristics measured in pure water. However, the ultrasonic characteristic in brain is different from that in pure water, which is critical for practical application. This study investigates the transcranial focused ultrasound attenuation with multilayer head model. Based on the realistic geometry and biological tissue property of head model, a three-layer head model was constructed to simulate ultrasound wave propagation and explore its attenuation and offset. In addition, the effects of single-layer biological tissue on ultrasound was explored, include scalp, skull and brain tissue. Compared with that of pure water medium, the focal length of transcranial focused ultrasound is shortened by 8.2% and focal spot is diverged by 47.8% in head model. Besides, the total acoustic pressure attenuation is about 89% and 19dB. In single-layer biological tissue, the skull is the biggest influencing factor founded for the attenuation of ultrasound pressure. Result demonstrate that sound field characteristics of transcranial focused ultrasound has changed from the ones in pure water medium, which is of guidance for practical application.