title: Collecting system percutaneous access using real-time tracking sensors: first pig model in vivo experience.
abstract: OBJECTIVE
  Precise needle puncture of the renal collecting system is an essential but challenging step for successful percutaneous nephrolithotomy. We evaluated the efficiency of a new real-time electromagnetic tracking system for in vivo kidney puncture.
  
  
  METHODS
  Six anesthetized female pigs underwent ureterorenoscopy to place a catheter with an electromagnetic tracking sensor into the desired puncture site and ascertain puncture success. A tracked needle with a similar electromagnetic tracking sensor was subsequently navigated into the sensor in the catheter. Four punctures were performed by each of 2 surgeons in each pig, including 1 each in the kidney, middle ureter, and right and left sides. Outcome measurements were the number of attempts and the time needed to evaluate the virtual trajectory and perform percutaneous puncture.
  
  
  RESULTS
  A total of 24 punctures were easily performed without complication. Surgeons required more time to evaluate the trajectory during ureteral than kidney puncture (median 15 seconds, range 14 to 18 vs 13, range 11 to 16, p=0.1). Median renal and ureteral puncture time was 19 (range 14 to 45) and 51 seconds (range 45 to 67), respectively (p=0.003). Two attempts were needed to achieve a successful ureteral puncture. The technique requires the presence of a renal stone for testing.
  
  
  CONCLUSIONS
  The proposed electromagnetic tracking solution for renal collecting system puncture proved to be highly accurate, simple and quick. This method might represent a paradigm shift in percutaneous kidney access techniques.
authors.affiliation: Life and Health Sciences Research Institute, School of Health Sciences, University of Minho, Braga, Portugal; 3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal; Algoritmi Center, School of Engineering, University of Minho, Guimarães, Portugal. Electronic address: pedrorodrigues@ecsaude.uminho.pt.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Rodrigues
authors.forename: João L
authors.initials: JL
authors.lastname: Vilaça
authors.forename: Carlos
authors.initials: C
authors.lastname: Oliveira
authors.forename: Antonio
authors.initials: A
authors.lastname: Cicione
authors.forename: Jens
authors.initials: J
authors.lastname: Rassweiler
authors.forename: Jaime
authors.initials: J
authors.lastname: Fonseca
authors.forename: Nuno F
authors.initials: NF
authors.lastname: Rodrigues
authors.forename: Jorge
authors.initials: J
authors.lastname: Correia-Pinto
authors.forename: Estevão
authors.initials: E
authors.lastname: Lima
mesh_terms: D000818:Animals; D003199:Computer Systems; D055590:Electromagnetic Phenomena; D005260:Female; D007685:Kidney Tubules, Collecting / Q000601:surgery*; D009403:Nephrostomy, Percutaneous / Q000379:methods*; D011677:Punctures / Q000379:methods*; D013552:Swine
keywords: 2-dimensional; 2D; 3-dimensional; 3D; EMT; PCNL; SCU; SIU; computer-assisted; electromagnetic tracking; imaging; instrumentation; kidney; nephrostomy; percutaneous; percutaneous nephrolithotomy; sensor interface unit; surgery; system control unit; three-dimensional