Prostate histotripsy: evaluation of prostatic urethral treatment parameters in a canine model.

Abstract

OBJECTIVE: To assess the impact of histotripsy treatment parameters (pulse number and pulse-repetition frequency [PRF]) on the efficiency of histotripsy induced homogenisation of the prostatic urethra. MATERIALS AND METHODS: In all, 34 transabdominal prostate histotripsy treatments were applied along a perpendicular plane traversing the prostatic urethra of 21 dogs. Prostate histotripsy was applied with (i) escalating pulse number with fixed PRF or (ii) at fixed pulse number with varying PRFs. The development of urethral homognisation ≤14 days of histotripsy was evaluated endoscopically and confirmed histologically. RESULTS: Within 14 days of histotripsy 50%, 83%, 83%, and 100% of dogs receiving 12 500, 25 000, 50 000, and 100 000 pulses/mm of treatment path (delivered at 500 Hz PRF), respectively developed prostatic urethral disintegration. Delivery of 100 000 pulses/mm was required to achieve urethral disintegration in all dogs within 24 h of histotripsy treatment. Increasing histotripsy PRF from 50 to 500 to 2000 Hz while applying a constant dose of 25 000 pulses/mm treatment was associated with increased rate of urethral disintegration (50% vs 75% vs 100% at 14 days, respectively). CONCLUSIONS: Increasing the number of histotripsy pulses and/or increasing the PRF of histotripsy treatment applied to the urethra may improve the rate and efficiency of prostatic urethral disintegration in the canine model. This understanding will aid in the development of treatment strategies for prostate histotripsy for benign prostatic hyperplasia in human trials.