title: MRI-guided robotic prostate biopsy: a clinical accuracy validation.
abstract: Prostate cancer is a major health threat for men. For over five years, the U.S. National Cancer Institute has performed prostate biopsies with a magnetic resonance imaging (MRI)-guided robotic system.
  
  
  OBJECTIVE
  A retrospective evaluation methodology and analysis of the clinical accuracy of this system is reported.
  
  
  METHODS
  Using the pre and post-needle insertion image volumes, a registration algorithm that contains a two-step rigid registration followed by a deformable refinement was developed to capture prostate dislocation during the procedure. The method was validated by using three-dimensional contour overlays of the segmented prostates and the registrations were accurate up to 2 mm.
  
  
  RESULTS
  It was found that tissue deformation was less of a factor than organ displacement. Out of the 82 biopsies from 21 patients, the mean target displacement, needle placement error, and clinical biopsy error was 5.9 mm, 2.3 mm, and 4 mm, respectively.
  
  
  CONCLUSIONS
  The results suggest that motion compensation for organ displacement should be used to improve targeting accuracy.
authors.affiliation: Queen's University, Kingston, Canada. helen@cs.queensu.ca
authors.forename: Helen
authors.initials: H
authors.lastname: Xu
authors.forename: Andras
authors.initials: A
authors.lastname: Lasso
authors.forename: Siddharth
authors.initials: S
authors.lastname: Vikal
authors.forename: Peter
authors.initials: P
authors.lastname: Guion
authors.forename: Axel
authors.initials: A
authors.lastname: Krieger
authors.forename: Aradhana
authors.initials: A
authors.lastname: Kaushal
authors.forename: Louis L
authors.initials: LL
authors.lastname: Whitcomb
authors.forename: Gabor
authors.initials: G
authors.lastname: Fichtinger
mesh_terms: D001707:Biopsy, Needle / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D011471:Prostatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012371:Robotics / Q000379:methods*; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*