The Effect of the Temporal Bone on Ultrasound Transmission

Focused ultrasound (FUS) has shown great promise in the field of neuromodulation. FUS is under investigation as a novel treatment for mesial temporal lobe epilepsy (MTLE) through modulating the hippocampus. The loss of energy transmission through a series of locations along a segment of ex vivo human skull has been investigated to determine the most effective treatment paths. Experimentally, a 0.5-MHz planar transducer was used to sonicate through two segments of ex vivo human temporal skull bone. Analysis of the scanned field enabled a determination of the level of attenuation and distortion of the transmitted signal. After successful transmission measurements of the temporal bone specimens, comparative analysis with simulations created using the Matlab package kWave was performed. A series of 2D simulations were compared with a matching scan performed on a segment of the skull, using density data as obtained from CT scans of the bone specimens. The resulting data will allow for the prediction of transmission fields for human patients using existing CT scans, enabling an assessment of the treatment path.