Strategy in Passively Reconstructing and Correcting Transcranial Focal Beam via Dual-Mode Ultrasound Phased Array

Focused ultrasound has been pointed out the theoretical and technical feasibility to reconstruct image for monitoring ultrasound CNS therapeutic efficacy via the transcranial way. However, practically the transcranial ultrasound still encounters severe challenges including severe phase aberration and attenuation due to the skull to abrupt the backscattered beamforming. This study proposes a correlation average correction algorithm with the intention to reconstruct the focal beam even encounter skull-insert severe phase aberration. The algorithm is implemented in a dual-mode ultrasound 256-channel phased array system operated at full-channel emission and sparse-channel receiving (32 channels). The concept is based on the use of averaged phase-aberration correlation to reduce phase aberration as well as to gain the image contrast-to-noise ratio. In-vitro transcranial experiments were conducted to evaluate the performance of the beam corrected reconstruction algorithm. Results showed that transcranial focal beam distribution can be successfully reconstructed in a weakly scattered tissue-mimicking skull-inserted phantom, and the image intensity was evaluated to highly correlated with the in-situ deposited pressure level. The results of this study may provide implication directing the potential to use ultrasound phased array to simultaneously perform transcranial focal beam guidance for ultrasound brain therapy application such as BBB opening.