title: Focused ultrasound to expel calculi from the kidney: safety and efficacy of a clinical prototype device.
abstract: OBJECTIVE
  Focused ultrasound has the potential to expel small stones or residual stone fragments from the kidney, or move obstructing stones to a nonobstructing location. We evaluated the efficacy and safety of ultrasonic propulsion in a live porcine model.
  
  
  METHODS
  Calcium oxalate monohydrate kidney stones and laboratory model stones (2 to 8 mm) were ureteroscopically implanted in the renal pelvicalyceal system of 12 kidneys in a total of 8 domestic swine. Transcutaneous ultrasonic propulsion was performed using an HDI C5-2 imaging transducer (ATL/Philips, Bothell, Washington) and the Verasonics® diagnostic ultrasound platform. Successful stone relocation was defined as stone movement from the calyx to the renal pelvis, ureteropelvic junction or proximal ureter. Efficacy and procedure time was determined. Three blinded experts evaluated histological injury to the kidney in the control, sham treatment and treatment arms.
  
  
  RESULTS
  All 26 stones were observed to move during treatment and 17 (65%) were relocated successfully to the renal pelvis (3), ureteropelvic junction (2) or ureter (12). Average ± SD successful procedure time was 14 ± 8 minutes and a mean of 23 ± 16 ultrasound bursts, each about 1 second in duration, were required. There was no evidence of gross or histological injury to the renal parenchyma in kidneys exposed to 20 bursts (1 second in duration at 33-second intervals) at the same output (2,400 W/cm(2)) used to push stones.
  
  
  CONCLUSIONS
  Noninvasive transcutaneous ultrasonic propulsion is a safe, effective and time efficient means to relocate calyceal stones to the renal pelvis, ureteropelvic junction or ureter. This technology holds promise as a useful adjunct to surgical management for renal calculi.
authors.affiliation: Department of Urology, School of Medicine, University of Washington, Seattle, Washington 98195, USA. jdharper@uw.edu
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Harper
authors.forename: Mathew D
authors.initials: MD
authors.lastname: Sorensen
authors.forename: Bryan W
authors.initials: BW
authors.lastname: Cunitz
authors.forename: Yak-Nam
authors.initials: YN
authors.lastname: Wang
authors.forename: Julianna C
authors.initials: JC
authors.lastname: Simon
authors.forename: Frank
authors.initials: F
authors.lastname: Starr
authors.forename: Marla
authors.initials: M
authors.lastname: Paun
authors.forename: Barbrina
authors.initials: B
authors.lastname: Dunmire
authors.forename: H Denny
authors.initials: HD
authors.lastname: Liggitt
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Evan
authors.forename: James A
authors.initials: JA
authors.lastname: McAteer
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Hsi
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bailey
mesh_terms: D000818:Animals; D002129:Calcium Oxalate / Q000737:chemistry; D004195:Disease Models, Animal; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D007150:Immunohistochemistry; D007669:Kidney Calculi / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D008096:Lithotripsy / Q000379:methods; D013552:Swine; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000295:instrumentation* / Q000379:methods*; D014463:Ultrasonography
chemical_list: D002129:Calcium Oxalate
keywords: SWL; UPJ; kidney; kidney calculi; lithotripsy; shock wave lithotripsy; ultrasonography; ureteropelvic junction; ureteroscopy