Correcting Transcranial Ultrasound Aberrations through Acoustoelectric Derived Time Reversal Operations

Transcranial ultrasound (US) is impeded by attenuation and aberration of the pressure wave induced by the skull. One method for correcting for these errors is through time-reversal of the transmit US waveform. However, robust innate acoustic reflectors, which are typically necessary for time-reversal US, do not exist in the brain. Some methods exist to either create or embed reflectors or US emitters at target locations. However, these methods lack in either specificity, accuracy or are invasive. In this paper we explore the use of acoustoelectric imaging (AEI) in order to utilize an electrical current as a point for performing time-reversal aberration corrections. We modeled a section of human skull and brain in MatLab and used the k- Wave package to simulate transcranial US propagation. A monopole was modeled in the brain in order to simulate AEI for performing time-reversal and correct for focal aberrations. Our AEI TR results were compared to TR delays determined through direct detection of the pressure wave itself for validation. Both TR methods resulted in very similar pressure profiles at the target focal point and outperformed an uncorrected delay profile in lateral FWHM (1.17 vs 3.4), peak amplitude (0.41MPa vs 0.24MPa), and side lobe power (-27dB vs 17dB). Collectively, these results advocate the use of AEI for utilizing current sources in the brain, natural or implanted, as a source for performing TR-based aberration corrections and enhancing transcranial US focus.