title: Feasibility of 3.0T magnetic resonance imaging-guided laser ablation of a cadaveric prostate.
abstract: OBJECTIVE
  To demonstrate the feasibility of 3.0T magnetic resonance imaging (MRI)-guided laser ablation of the prostate.
  
  
  METHODS
  MRI-guided laser ablations in the intact prostate gland were performed in 5 cadavers. The cadavers were brought into the MRI suite and placed in a supine headfirst position. A needle guide grid was placed against the perineum, and MRI was performed to co-localize the grid with the prostate imaging data set. Using the guidance grid and 14-gauge Abbocath catheters, the laser applicators were placed in the prostate with intermittent MRI guidance. After confirmation of the position of the laser applicators, 2-minute ablations were performed with continuous MRI temperature feedback. Using the relative change in temperature and the Arrhenius model of thermal tissue ablation, the ablation margins were calculated.
  
  
  RESULTS
  Laser ablation was successfully performed in all 5 cadaveric prostates using 15- and 30-W laser generators. Thermal mapping in the axial, sagittal, and coronal planes was performed with calculated ablation margins projected back onto the magnitude MR images. Deviations of the needles from the template projections ranged from 1.0 to 4.1 mm (average 2.1) at insertion depths of 75.5-116.5 mm (average 98.2). In the 2 cadavers for which histologic correlation was available, the extent of the ablation zone corresponded to the temperature mapping findings and the ablation transition zones were identifiable on hematoxylin-eosin staining.
  
  
  CONCLUSIONS
  Transperineal laser ablation of the prostate gland is possible using 3.0T MRI guidance and thermal mapping and offers the potential for precise image-guided focal targeting of prostate cancer.
authors.affiliation: Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA. woodrum.david@mayo.edu
authors.forename: David A
authors.initials: DA
authors.lastname: Woodrum
authors.forename: Krzysztof R
authors.initials: KR
authors.lastname: Gorny
authors.forename: Lance A
authors.initials: LA
authors.lastname: Mynderse
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Amrami
authors.forename: Joel P
authors.initials: JP
authors.lastname: Felmlee
authors.forename: Haraldur
authors.initials: H
authors.lastname: Bjarnason
authors.forename: Oscar I
authors.initials: OI
authors.lastname: Garcia-Medina
authors.forename: Roger J
authors.initials: RJ
authors.lastname: McNichols
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Atwell
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Callstrom
mesh_terms: D002102:Cadaver; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D007150:Immunohistochemistry; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D053844:Lasers, Solid-State / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011467:Prostate / Q000473:pathology* / Q000601:surgery*; D012680:Sensitivity and Specificity