MRI-guided robotic prostate biopsy: a clinical accuracy validation.
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.
Xu
Helen
H
Queen's University, Kingston, Canada. helen@cs.queensu.ca
Lasso
Andras
A
Vikal
Siddharth
S
Guion
Peter
P
Krieger
Axel
A
Kaushal
Aradhana
A
Whitcomb
Louis L
LL
Fichtinger
Gabor
G
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*