Mechanisms underlying PRF-dependent lesion growth in HCT histotripsy

Establish the mechanistic basis for why lesions did not grow at 100 Hz but continued to expand at 1 kHz during 1–10 second treatments using 10 µs pulses inside a hollow cylindrical transducer lumen, including whether bubble-memory effects and PRF-dependent modifications to the lateral pressure field drive enhanced off-axis erosion at higher PRF.

Background

The authors observed that for 10 µs pulses, lesions at 100 Hz showed no significant growth from 1 to 10 seconds, whereas at 1 kHz lesions enlarged and expanded radially beyond the on-axis high-pressure region. They hypothesize that bubble-memory effects and residual gas may alter cloud characteristics and the surrounding pressure field, potentially facilitating lateral erosion at higher PRF.

Identifying the dominant mechanisms would guide optimization of PRF and pulse sequencing to maximize erosion efficiency while controlling lesion geometry in an intravascular HCT setting.