title: Comparison of manual and computer assisted ultrasonic guidance for transparenchymal percutaneous renal needle placement.
abstract: OBJECTIVE
  We evaluated a novel computer based guidance system for deploying needles into the renal parenchyma. We compared it to current standards, including a fixed needle guide and a freehand technique.
  
  
  METHODS
  We performed an in vitro comparison followed by a porcine trial. The in vitro model consisted of a bath of ultrasound medium with suspended metallic targets. We compared the number of attempts and the time needed by the novel guide design with and without its software and a support arm vs the freehand approach. In the porcine model we tested the software guide with and without a support arm for targeting a 5 mm lesion embedded in the renal parenchyma. Impressions of difficulty, time, the number of attempts, needle tip visualization and needle tip divergence were documented.
  
  
  RESULTS
  Compared to freehand targeting the software guide and support arm decreased the number of targeting attempts in the in vitro model from 4.8 to 1.6 (p <0.001) and decreased the time required from 31.8 to 11.4 seconds (p <0.001). In the porcine study needle tip visualization with the software and support arm received an average score of 1.3 vs 1.8 with the software guide alone (p = 0.04). Tip divergence received a score of 1.4 with the arm and 1.8 without it (p = 0.07). Overall contribution received a score of 1.4 with and without the support arm (p = 0.35).
  
  
  CONCLUSIONS
  Computer assisted needle deployment decreased the time and number of attempts required to successfully target simulated parenchymal lesions and also decreased the subjective difficulty inherent in the standard freehand approach.
authors.affiliation: Department of Urology, Columbia University Medical Center, New York, New York, USA.
authors.forename: Jason F
authors.initials: JF
authors.lastname: Skenazy
authors.forename: Gabriella
authors.initials: G
authors.lastname: Mirabile
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Hruby
authors.forename: Ingrid
authors.initials: I
authors.lastname: Lauer-Arnold
authors.forename: Mantu
authors.initials: M
authors.lastname: Gupta
authors.forename: Jaime
authors.initials: J
authors.lastname: Landman
mesh_terms: D000818:Animals; D044963:Biopsy, Fine-Needle / Q000295:instrumentation* / Q000379:methods; D003936:Diagnosis, Computer-Assisted / Q000295:instrumentation*; D004195:Disease Models, Animal; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D066298:In Vitro Techniques; D007668:Kidney / Q000000981:diagnostic imaging / Q000473:pathology*; D011336:Probability; D012307:Risk Factors; D012680:Sensitivity and Specificity; D034421:Sus scrofa; D013552:Swine; D013997:Time Factors; D018084:Ultrasonography, Interventional / Q000295:instrumentation* / Q000379:methods