title: Transperineal prostate biopsy under magnetic resonance image guidance: a needle placement accuracy study.
abstract: OBJECTIVE
  To quantify needle placement accuracy of magnetic resonance image (MRI)-guided core needle biopsy of the prostate.
  
  
  METHODS
  A total of 10 biopsies were performed with 18-gauge (G) core biopsy needle via a percutaneous transperineal approach. Needle placement error was assessed by comparing the coordinates of preplanned targets with the needle tip measured from the intraprocedural coherent gradient echo images. The source of these errors was subsequently investigated by measuring displacement caused by needle deflection and needle susceptibility artifact shift in controlled phantom studies. Needle placement error due to misalignment of the needle template guide was also evaluated.
  
  
  RESULTS
  The mean and standard deviation (SD) of errors in targeted biopsies was 6.5 +/- 3.5 mm. Phantom experiments showed significant placement error due to needle deflection with a needle with an asymmetrically beveled tip (3.2-8.7 mm depending on tissue type) but significantly smaller error with a symmetrical bevel (0.6-1.1 mm). Needle susceptibility artifacts observed a shift of 1.6 +/- 0.4 mm from the true needle axis. Misalignment of the needle template guide contributed an error of 1.5 +/- 0.3 mm.
  
  
  CONCLUSIONS
  Needle placement error was clinically significant in MRI-guided biopsy for diagnosis of prostate cancer. Needle placement error due to needle deflection was the most significant cause of error, especially for needles with an asymmetrical bevel.
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Blumenfeld
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hata
authors.forename: Simon
authors.initials: S
authors.lastname: DiMaio
authors.forename: Kelly
authors.initials: K
authors.lastname: Zou
authors.forename: Steven
authors.initials: S
authors.lastname: Haker
authors.forename: Gabor
authors.initials: G
authors.lastname: Fichtinger
authors.forename: Clare M C
authors.initials: CM
authors.lastname: Tempany
mesh_terms: D000368:Aged; D016477:Artifacts; D001707:Biopsy, Needle / Q000379:methods*; D003287:Contrast Media / Q000494:pharmacology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009339:Needles; D019047:Phantoms, Imaging; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media