Simulating performance of a through-transmit aberration correction method for transcranial focused ultrasound

Transcranial focused ultrasound (tFUS) is a promising neuromodulation tool but typically demands subject-specific aberration correction based on pre-acquired CT images. A method that does not rely on CT is desirable. Riis et al. developed a method, called relativistic through-transmit (RTT), that corrects by comparing through-skull signals to free-field signals from two opposing transducer arrays positioned on either side of the head. RTT showed promise in deep-brain regions, but its robustness under noise, steering, and positioning uncertainties is not well characterized. To evaluate RTT’s performance, we performed 2-D k-wave simulations modeling commercially available transducers in a through-transmit arrangement across a non-human primate skull. To avoid instability in published iterative phase correction methods, we corrected by pseudoinverse. To quantify efficacy, we measured corrected through-skull pressure and focal position. In an ideal case (no uncertainties, etc.), RTT restored 102% of the intended pressure at spatial peak (2.3 mm focal shift) and 92% at target. Performance varied between targets, restoring 56%–78% pressure when steering 10 mm off-axis. In 20 simulations where we applied random transducer position uncertainties up to 4 mm, RTT delivered 81%–108% pressure (mean = 95%, s.d. = 7%). This work provides the first theoretical analysis of a novel aberration correction method and the groundwork for methodological improvements.