title: Rapid freehand MR-guided percutaneous needle interventions: an image-based approach to improve workflow and feasibility.
abstract: OBJECTIVE
  To develop and evaluate software-based methods for improving the workflow of magnetic resonance (MR)-guided percutaneous interventions.
  
  
  METHODS
  A set of methods was developed that allows the user to: 1) plan an entire procedure, 2) directly apply this plan to skin entry site localization without further imaging, and 3) place a needle under real-time MR guidance with automatic alignment of three orthogonal slices along a planned trajectory with preference to the principal patient axes. To validate targeting accuracy and time, phantom experiments (96 targets) and in vivo paraspinal and kidney needle punctures in two pigs (55 targets) were performed. The influence of trajectory obliquity, level of experience, and organ motion on targeting accuracy and time was analyzed.
  
  
  RESULTS
  Mean targeting error was 1.8 ± 0.9 mm (in vitro) and 2.9 ± 1.0 mm (in vivo) in all directions. No statistically significant differences in targeting accuracy between single- and double-oblique trajectories, novice and expert users, or paraspinal and kidney punctures were observed. The average time (in vivo) from trajectory planning to verification of accurate needle placement was 6 minutes.
  
  
  CONCLUSIONS
  The developed methods allow for accurate needle placement along complex trajectories and are anticipated to reduce table time for MR-guided percutaneous needle interventions.
authors: Friedrich Alexander University, Pattern Recognition Lab, Department of Computer Science, Erlangen, Germany. eva.rothgang@informatik.uni-erlangen.de
authors: Eva
authors: E
authors: Rothgang
authors: Wesley D
authors: WD
authors: Gilson
authors: Frank
authors: F
authors: Wacker
authors: Joachim
authors: J
authors: Hornegger
authors: Christine H
authors: CH
authors: Lorenz
authors: Clifford R
authors: CR
authors: Weiss
mesh_terms: D055011:Ablation Techniques / Q000295:instrumentation / Q000379:methods*; D000465:Algorithms; D000818:Animals; D001707:Biopsy, Needle / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D061705:Image-Guided Biopsy / Q000295:instrumentation / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D007267:Injections / Q000295:instrumentation / Q000379:methods*; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D013552:Swine; D057188:Workflow