title: Comparison of freehand-navigated and aiming device-navigated targeting of liver lesions.
abstract: BACKGROUND
  Accurate needle placement is crucial for the success of percutaneous radiological needle interventions. We compared three guiding methods using an optical-based navigation system: freehand, using a stereotactic aiming device and active depth control, and using a stereotactic aiming device and passive depth control.
  
  
  METHODS
  For each method, 25 punctures were performed on a non-rigid phantom. Five 1 mm metal screws were used as targets. Time requirements were recorded, and target positioning errors (TPE) were measured on control scans as the distance between needle tip and target.
  
  
  RESULTS
  Time requirements were reduced using the aiming device and passive depth control. The Euclidian TPE was similar for each method (4.6 ± 1.2-4.9 ± 1.7 mm). However, the lateral component was significantly lower when an aiming device was used (2.3 ± 1.3-2.8 ± 1.6 mm with an aiming device vs 4.2 ± 2.0 mm without).
  
  
  CONCLUSIONS
  Using an aiming device may increase the lateral accuracy of navigated needle insertion.
authors.affiliation: University of Bern, ARTORG Centre for Biomedical Engineering Research, Bern, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Wallach
authors.forename: G
authors.initials: G
authors.lastname: Toporek
authors.forename: S
authors.initials: S
authors.lastname: Weber
authors.forename: R
authors.initials: R
authors.lastname: Bale
authors.forename: G
authors.initials: G
authors.lastname: Widmann
mesh_terms: D002138:Calibration; D004867:Equipment Design; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy*; D008670:Metals / Q000737:chemistry; D009339:Needles; D019047:Phantoms, Imaging; D011677:Punctures / Q000295:instrumentation; D015641:Radiography, Interventional / Q000295:instrumentation*; D015203:Reproducibility of Results; D012371:Robotics; D013238:Stereotaxic Techniques / Q000295:instrumentation; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed
chemical_list: D008670:Metals
keywords: image-guided therapy; interventional radiology; stereotaxy