Cavitation Control for Enhanced Comminution of Renal Calculi.

[摘要] Shock wave lithotripsy (SWL) revolutionized the treatment of kidney stones when first introduced three decades ago. Instead of open stone surgery, ultrasonic shock waves could be applied from outside the body to fragment stones in-situ, offering a non-invasive approach to stone therapy. Although still widely utilized for the treatment of stones, SWL has yet to realize its full potential. Incomplete stone fragmentation and damage to surrounding tissues are common problems plaguing SWL procedures, and despite the fact that much progress has been made in understanding the mechanisms underlying these phenomena, implementation of this knowledge to improve clinical outcomes has been minimal. One of the fundamental components underlying stone fragmentation in SWL is the energetic formation and collapse of microscopic bubbles. This behavior—known as cavitation—can be incited by extremely intense ultrasound pulses such as the shock waves administered in lithotripsy procedures. The role of cavitation in SWL is twofold: violent collapse of bubbles generated at the stone surface confers large stresses to the structure of the stone, and is a crucial component of fragmentation; contrastingly, bubbles generated away from the stone along the acoustic propagation path can block energy from reaching the stone and compromise comminution efficacy.The work in this dissertation seeks to augment conventional SWL procedures through strategic control of the cavitation environment surrounding a kidney stone. This is achieved by way of two ultrasonic pulsing strategies designed to either enhance or suppress cavitation activity: 1) Histotripsy sequences, developed previously as a non-invasive therapeutic ultrasound technology for the mechanical fractionation of tissue structures, utilize very intense bursts of ultrasound to initiate and control a cavitational bubble cloud. 2) Bubble removal sequences, developed herein to mitigate unwanted cavitation activity, utilize low amplitude ultrasound bursts to stimulate the consolidation and de facto removal of cavitation bubble nuclei. Through appropriate application of these modalities for cavitation control, it is possible to enhance the comminution process for faster, more complete stone treatments. Ultimately, it is our hope that the concepts developed in this dissertation will provide the foundation for an enhanced first-line treatment for the non-invasive removal of kidney stones.

[发布机构] University of Michigan

[效力级别] Shock Wave Lithotripsy

[关键词] Histotripsy;Shock Wave Lithotripsy;Cavitation Control;Biomedical Engineering;Engineering;Health Sciences;Biomedical Engineering