The effect of histotripsy on tissues with different mechanical properties

Histotripsy is a non-invasive mechanical tissue ablation method that depends on the initiation and maintenance of a cavitation bubble cloud to mechanically fractionate soft tissue. The effect of histotripsy on tissue has been observed to vary depending on their mechanical properties. Tissue fractionation induced by histotripsy is often self-limiting at anatomical boundaries of tougher tissue such as blood vessels. This paper studies how histotripsy affects tissue with different mechanical properties. The pressure threshold to initiate the cavitation bubble cloud in tissue with varying properties, including elastic modulus, water content, and density, was measured, and the resulting tissue fractionation was evaluated. Results demonstrate a significant increase in cavitation cloud initiation threshold and a significant decrease in the extent of tissue damage for tissues of increased mechanical strength. Cavitation cloud initiation threshold increased in tissues with higher ultimate strength, higher density, and lower water content. Resistance to histotripsy damage was shown to increase for tissues with higher ultimate strength and density. These results improve our understanding of the effect of histotripsy on tissue with different mechanical properties and provide a rational basis to tailor acoustic parameters for fractionation of specific tissues.