title: Focused ultrasound guided relocation of kidney stones.
abstract: OBJECTIVE
  Complete removal of all fragments is the goal of any intervention for urinary stones. This is more important in lower pole stones where gravity and spatial orientation of lower pole infundibulum may hinder spontaneous passage of fragments. Various adjuvant therapies (inversion, diuresis, percussion, oral citrate, etc.) are described to enhance stone-free rate but are not widely accepted. Focused ultrasound-guided relocation of fragments is a recently described technique aimed at improving results of intervention for stone disease. Purpose of this review is to discuss development of this technology and its potential clinical applications.
  
  
  METHODS
  Pubmed search was made using key words "Focused ultrasound" and "kidney stone". All English language articles were reviewed by title. Relevant studies describing development and application of focused ultrasound in renal stones were selected for review.
  
  
  RESULTS
  Focused ultrasound has proven its efficacy in successfully relocating up to 8 mm stone fragments in vitro and in pigs. Relocation is independent of stone composition. The latest model allows imaging and therapy with a single handheld probe facilitating its use by single operator. The acoustic energy delivered by the new prototype is even less than that used for extracorporeal shock wave lithotripsy. Therapeutic exposure has not caused thermal injury in pig kidneys.
  
  
  CONCLUSIONS
  Focused ultrasound-guided relocation of stones is feasible. Though it is safe in application in pigs, technology is awaiting approval for clinical testing in human beings. This technology has many potential clinical applications in the management of stone disease.
authors.affiliation: Department of Urology, Christian Medical College, Vellore, India.
authors.forename: Nitin
authors.initials: N
authors.lastname: Abrol
authors.affiliation: Department of Urology, Christian Medical College, Vellore, India.
authors.forename: Nitin S
authors.initials: NS
authors.lastname: Kekre
keywords: Focused ultrasound; relocation; renal calculi; stone-free rate