A full-wave phase aberration correction method for transcranial high-intensity focused ultrasound brain therapies

Transcranial high-intensity focused ultrasound has recently been used to noninvasively treat several types of brain disorders. However, due to the large differences in acoustic properties of skulls and the surrounding soft tissue, it can be a challenge to adequately focus an ultrasonic beam through the skull. We present a novel, fast, full-wave method of correcting the aberrations caused by the skull by phasing the elements of a phased-array transducer to create constructive interference at the target. Because the method is full-wave, it also allows for trajectory planning by determining the phases required for multiple target points with negligible additional computational costs. Experimental hydrophone scans with an ex vivo skull sample using a 256-element 1-MHz transducer show an improvement of 6.2% in peak pressure at the focus and a reduction of side-lobe pressure by a factor of 2.31. Additionally, mispositioning of the peak pressure from the intended treatment location is reduced from 2.3 to 0.5 mm.