Design of a histotripsy array for the treatment of intracerebral hemorrhage

Histotripsy is a focused ultrasound technique using short, high amplitude pulses to generate targeted cavitation. Recently, the feasibility to treat blood clots through human skulls with histotripsy has been shown in vitro. The purpose of this study was to evaluate acoustic parameters for developing an optimized array design for the treatment of intracerebral hemorrhage (ICH) with histotripsy. The main performance criteria were to achieve a large electronic focal steering range (≥ 20 mm) and an ability to correct aberration through the skull. A hemispherical aperture of 150 mm radius was considered with modular elements to allow for arbitrary insertion of a catheter hydrophone to perform aberration correction. The attenuation at discrete frequencies from 250 kHz–2 MHz was measured through excised human skulls (n = 7) along with effects of incidence angle and aberration to optimize the operating frequency. Different piezoelectric materials were tested to optimize the peak-output, transduction efficiency, and durability at high PRF. One of the best performers, 17 mm square PZ36 material at 700 kHz, was found to produce at least 1.5 MPa free field at PRFs of 1 kHz. Finally, simulation showed that an optimally packed array configuration using 360 modules should be able to achieve an effective steering range of at least ±20 mm through the skull.Histotripsy is a focused ultrasound technique using short, high amplitude pulses to generate targeted cavitation. Recently, the feasibility to treat blood clots through human skulls with histotripsy has been shown in vitro. The purpose of this study was to evaluate acoustic parameters for developing an optimized array design for the treatment of intracerebral hemorrhage (ICH) with histotripsy. The main performance criteria were to achieve a large electronic focal steering range (≥ 20 mm) and an ability to correct aberration through the skull. A hemispherical aperture of 150 mm radius was considered with modular elements to allow for arbitrary insertion of a catheter hydrophone to perform aberration correction. The attenuation at discrete frequencies from 250 kHz–2 MHz was measured through excised human skulls (n = 7) along with effects of incidence angle and aberration to optimize the operating frequency. Different piezoelectric materials were tested to optimize the peak-output, transduction efficiency, a...