Portable Ultrasound Imaging of the Brain for Use in Forward Battlefield Areas

The overall goal of this project has been to develop i an ultrasound-based detection system designed to detect foreign bodies in the brain and ii a portable ultrasound-based imaging system capable of producing full brain images through the intact skull. This year, based on preliminary designs and testing in Years I and II of the project, a final design and reconstruction approach has been established. Key findings and considerations leading to the design have been The determination that in many regions of the brain -particularly in critical areas in the center of the brain - access angles via shear-mode transcranial windowing through the skull bone simultaneously produce longitudinal modes that can interfere with the shear mode imaging. Signal-to-noise rations of the shear-mode-windowed signals can be greatly enhanced using narrowband transmission signals. Image resolution at the reduced operating frequency necessary to achieve transcranial propagation greatly benefit from an extended degree of imaging angles.