title: The digital flexible ureteroscope: in vitro assessment of optical characteristics.
abstract: BACKGROUND
  Recent advances in endoscope design have placed the charged coupled device chip on the tip of the endoscope. The image is instantly digitalized and converted into an electrical signal for transmission. Digital technology was first introduced into flexible cystoscopes/nephroscopes and subsequently into rigid and flexible ureteroscopes. Herein, we assess the image characteristics and advantages of a new generation of digital flexible ureteroscopes.
  
  
  METHODS
  The Olympus URF-V flexible digital ureteroscope and the Olympus URF-P3 fiberoptic ureteroscope were assessed in vitro for image resolution, distortion, color representation, grayscale imaging, field of view, and depth of field.
  
  
  RESULTS
  The digital ureteroscope had a higher resolution at 3, 5, 10, and 20 mm (25.2 lines/mm vs. 8.0, 14.1 vs. 5.0, 6.3 vs. 2.8, and 3.2 vs. 1.3), respectively. Distortion with the digital flexible ureteroscope was lower, though not statistically significant. Color representation was better with the digital ureteroscope, whereas contrast evaluation was comparable between both scopes. The digital flexlible ureteroscope produced a 5.3 times larger image size compared with the standard fiberoptic flexible uretersocpe with a narrower field of view. The depth of field was limited by light and not the optic or the camera for both ureteroscopes.
  
  
  CONCLUSIONS
  The development of digital flexible ureteroscopes represents a significant technological advance in urology. These devices offer significantly improved resolution and color reproduction as compared with traditional fiberoptic flexible ureteroscopes. Future clinical trials are warranted to ultimately determine the advantages of these innovative endoscopes.
authors.affiliation: Division of Urologic Surgery, Comprehensive Kidney Stone Center, Duke University Medical Center, Durham, North Carolina 27710, USA. dorit.zilberman@duke.edu
authors.forename: Dorit E
authors.initials: DE
authors.lastname: Zilberman
authors.forename: Michael E
authors.initials: ME
authors.lastname: Lipkin
authors.forename: Michael N
authors.initials: MN
authors.lastname: Ferrandino
authors.forename: Walter Neal
authors.initials: WN
authors.lastname: Simmons
authors.forename: John G
authors.initials: JG
authors.lastname: Mancini
authors.forename: Maria E
authors.initials: ME
authors.lastname: Raymundo
authors.forename: Pei
authors.initials: P
authors.lastname: Zhong
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Preminger
mesh_terms: D003116:Color; D055620:Optical Phenomena; D018583:Pliability; D015203:Reproducibility of Results; D020709:Ureteroscopes