Pilot in vivo studies on transcutaneous boiling histotripsy in porcine liver and kidney

Abstract

Boiling histotripsy (BH) uses millisecond-long pulses of focused ultrasound (FUS) waves with shocks to mechanically homogenize tissue. Here we report a pilot in vivo acute study on transcutaneous volumetric BH ablation of porcine liver and kidney. BH treatment was administered using a 1.5 MHz FUS transducer operating at peak electric power ranging from 0.6 to 4 kW with B-mode ultrasound guidance using an imaging probe mounted coaxially. Sonication protocols delivered 5-30 pulses of 1-10 ms duration and 1% duty factor to focal points spaced 1-1.5 mm apart in a rectangular grid with 5-15 mm linear dimensions. Well-demarcated volumetric BH lesions were successfully generated in both liver and kidney without respiratory gating. The treatment was accelerated 6-fold without affecting the quality of tissue homogenization by using shorter duration BH pulses of larger peak power. These data indicate that transcutaneous volumetric renal and hepatic ablations are feasible in the in vivo porcine model. Studies are ongoing to optimize treatment parameters with the goal of clinical BH ablation of renal and hepatic masses. [This work was supported by NIH R01 EB7643, K01 EB015745, NSBRI through NASA NCC 9-58, RFBR 16-02-00653, and Urology Care Foundation.]