Three-layer model with absorption for conservative estimation of the maximum acoustic transmission coefficient through the human skull for transcranial ultrasound stimulation

• DOI: 10.1016/j.brs.2022.12.005
• Publication Date: 2022-12-19T16:46:45Z
• Authors: David Attali; Thomas Tiennot; Mark Schafer; Elsa Fouragnan; Jérôme Sallet; Charles F Caskey; Robert Chen; Ghazaleh Darmani; Ellen J. Bubrick; Christopher Butler; Charlotte J Stagg; Miriam Klein-Flügge; Lennart Verhagen; Seung-Schik Yoo; Kim Butts Pauly; Jean-Francois Aubry
• Keywords: Human head; Human skull

Transcranial ultrasound stimulation (TUS) has been shown to be a safe and effective technique for non-invasive superficial deep brain stimulation. Safe efficient translation humans requires estimating the acoustic attenuation of human skull. Nevertheless, there are no international guidelines impact skull bone. A tissue independent, arbitrary derating was developed by U.S. Food Drug Administration take into account absorption (0.3 dB/cm-MHz) diagnostic ultrasound. However, case transcranial imaging, FDA model does not insertion loss induced bone, nor tissue. Therefore, estimated is overly conservative which could potentially limit TUS applications if same were adopted. Here we propose three-layer including bone calculate maximum pressure transmission through frequencies ranging between 100 kHz 1.5 MHz. The calculated decreases with frequency thickness peaks each corresponding multiple half wavelength. 95th percentile over accessible surface 20 skulls 12 typical diameters beam on surface, varies 40% 78%. To facilitate adjustment short pulses, such as imaging or stimulation, table summarizes diameter frequency.