title: Novel ureteroscopic navigation system with a magnetic tracking device: a preliminary ex vivo evaluation.
abstract: OBJECTIVE
  Examination of the pyelocaliceal system using a flexible ureteroscope necessitates accurate orientation of the tip of the instrument. This study assessed the use of a novel real-time ureteroscopic navigation system in a pyelocaliceal phantom.
  
  
  METHODS
  The navigation system used a magnetic tracking device to determine the position of the ureteroscope in a pyelocaliceal phantom and displayed the position of the endoscope on a three-dimensional image that could be rotated. Twenty-eight urologists were divided into group A and group B (seven novice surgeons and seven experienced surgeons in each group). All participants were asked to examine the phantom and identify the positions of three designated calices, without the navigation system (Task 1) and with the navigation system (Task 2). In group A, participants performed Task 1 followed by Task 2. In group B, participants performed Task 2 followed by Task 1. The accuracy rate (AR) of identifying the calices, migration length (ML) of the tip of the ureteroscope, and time (T) taken to complete the task were recorded. The results were compared between Task 1 and Task 2, and between novice and experienced surgeons.
  
  
  RESULTS
  The AR for Task 2 was 100% in both group A and group B. The AR was significantly lower in Task 1 than in Task 2 for both novice and experienced surgeons in both groups (group A: novice P=0.016, experienced P=0.034; group B: novice P=0.015, experienced P=0.015; Wilcoxon test). In Group A, T was significantly longer in Task 1 than in Task 2 for experienced surgeons. There were no significant differences in ML or T between novice and experienced surgeons.
  
  
  CONCLUSIONS
  Our novel ureteroscopic navigation system improved the accuracy of ureteroscopic maneuvers. Further development of this system for use in clinical ureteroscopic procedures is planned.
authors.affiliation: Department of Urology and Andrology, Kansai Medical University , Osaka, Japan .
authors.forename: Kenji
authors.initials: K
authors.lastname: Yoshida
authors.forename: Gen
authors.initials: G
authors.lastname: Kawa
authors.forename: Hisanori
authors.initials: H
authors.lastname: Taniguchi
authors.forename: Takaaki
authors.initials: T
authors.lastname: Inoue
authors.forename: Takao
authors.initials: T
authors.lastname: Mishima
authors.forename: Masaaki
authors.initials: M
authors.lastname: Yanishi
authors.forename: Motohiko
authors.initials: M
authors.lastname: Sugi
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Kinoshita
authors.forename: Tadashi
authors.initials: T
authors.lastname: Matsuda
mesh_terms: D000328:Adult; D002983:Clinical Competence; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods; D007670:Kidney Calices; D060526:Magnetic Fields; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D020709:Ureteroscopes; D018666:Ureteroscopy / Q000193:education / Q000295:instrumentation* / Q000379:methods