Browsing by Subject "burst wave lithotripsy"

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    Impact of stone type on cavitation in burst wave lithotripsy
    (Acoustical Society of America, 2018-12-26) Hunter, Christopher; Maxwell, Adam D.; Cunitz, Bryan; Dunmire, Barbrina; Sorensen, Mathew D.; Williams, James C.; Randad, Akshay; Bailey, Michael; Kreider, Wayne; Anatomy and Cell Biology, School of Medicine
    Non-invasive kidney stone treatments such as shock wave lithotripsy (SWL) and burst wave lithotripsy (BWL) rely on the delivery of pressure waves through tissue to the stone. In both SWL and BWL, the potential to hinder comminution by exciting cavitation proximal to the stone has been reported. To elucidate how different stones alter prefocal cavitation in BWL, different natural and synthetic stones were treated in vitro using a therapy transducer operating at 350 kHz (peak negative pressure 7 MPa, pulse length 20 cycles, pulse repetition frequency 10 Hz). Stones were held in a confined volume of water designed to mimic the geometry of a kidney calyx, with the water filtered and degassed to maintain conditions for which the cavitation threshold (in the absence of a stone) matches that from in vivo observations. Stone targeting and cavitation monitoring were performed via ultrasound imaging using a diagnostic probe aligned coaxially with the therapy transducer. Quantitative differences in the extent and location of cavitation activity were observed for different stone types—e.g., “softer” stones (natural and synthetic) that disintegrate into “dusty” fragments produced larger prefocal cavitation clouds. Future work will focus on correlation of such cavitation metrics with stone fragmentation.
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    Update on clinical trials of kidney stone repositioning and preclinical results of stone breaking with one system
    (Acoustical Society of America, 2018-12-21) Bailey, Michael R.; Wang, Yak-Nam; Kreider, Wayne; Dai, Jessica C.; Cunitz, Bryan W.; Harper, Jonathan D.; Chang, Helena; Sorensen, Mathew D.; Liu, Ziyue; Levy, Oren; Dunmire, Barbrina; Maxwell, Adam D.; Biostatistics, School of Public Health
    Our goal is an office-based, handheld ultrasound system to target, detach, break, and/or expel stones and stone fragments from the urinary collecting system to facilitate natural clearance. Repositioning of stones in humans (maximum 2.5 MPa, and 3-second bursts) and breaking of stones in a porcine model (maximum 50 cycles, 20 Hz repetition, 30 minutes, and 7 MPa peak negative pressure) have been demonstrated using the same 350-kHz probe. Repositioning in humans was conducted during surgery with a ureteroscope in the kidney to film stone movement. Independent video review confirmed stone movements (≥ 3 mm) in 15 of 16 kidneys (94%). No serious or unanticipated adverse events were reported. Experiments of burst wave lithotripsy (BWL) effectiveness on breaking human stones implanted in the porcine bladder and kidney demonstrated fragmentation of 8 of 8 stones on post mortem dissection. A 1-week survival study with the BWL exposures and 10 specific-pathogen-free pigs, showed all findings were within normal limits on clinical pathology, hematology, and urinalysis. These results demonstrate that repositioning of stones with ultrasonic propulsion and breaking of stones with BWL are safe and effective.