Transcranial shear-mode ultrasound imaging Characterization of Point Spread Function and assessment of excitation techniques

This study presents work on an imaging technique that utilizes shear-wave propagation through the skull. The pulse-echo point spread functions (PSF) were obtained by imaging a point scatterer behind ex vivo human craniums at 1 MHz. Brightness images of the target obtained with either shear-mode or conventional longitudinal-mode transmission in the bone were assessed to quantify distortions to the PSF. The signal-to-noise ratio (SNR) limitations introduced by severe attenuation of shear-waves in the skull were overcome with frequency modulated (FM) coded excitations.