title: Visualization support for the planning of hepatic needle placement.
abstract: OBJECTIVE
  Percutaneous image-guided interventions, such as radiofrequency ablation or biopsy, are using needle-shaped instruments which have to be inserted into a target area without penetrating any vital structure. The established planning workflow is based on viewing 2D slices of a pre-interventional CT or MR scan. However, access paths not parallel to the axial plane are often necessary. For such complicated cases, the planning process is challenging and time consuming if solely based on 2D slices. To overcome these limitations while keeping the well-established workflow, we propose a visualization method that highlights less suited paths directly in the 2D visualizations with which the radiologist is familiar.
  
  
  METHODS
  Based on a user defined target point and segmentation masks of relevant risk structures, a risk structure map is computed using GPU accelerated volume rendering and projected onto the 2D slices. This visualization supports the user in defining safe linear access paths by selecting a second point directly in the 2D image slices.
  
  
  RESULTS
  In an evaluation for 20 liver radiofrequency ablation cases, 3 experienced radiologists stated for 55% of the cases that the visualization supported the access path choice. The visualization support was rated with an average mark of 2.2. For 2 of the 3 radiologists, a significant reduction of the planning duration by 54 and 50% was observed.
  
  
  CONCLUSIONS
  The proposed visualization approach can both accelerate the access path planning for radiofrequency ablation in the liver and facilitate the differentiation between safer and less safe paths.
authors.affiliation: Fraunhofer MEVIS - Institute for Medical Image Computing, Universitaetsallee 29, 28359, Bremen, Germany. christian.schumann@mevis.fraunhofer.de
authors.forename: Christian
authors.initials: C
authors.lastname: Schumann
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bieberstein
authors.forename: Stefan
authors.initials: S
authors.lastname: Braunewell
authors.forename: Matthias
authors.initials: M
authors.lastname: Niethammer
authors.forename: Heinz-Otto
authors.initials: HO
authors.lastname: Peitgen
mesh_terms: D001707:Biopsy, Needle / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008113:Liver Neoplasms / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011300:Preoperative Care / Q000379:methods; D015641:Radiography, Interventional / Q000379:methods*; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods