title: MR-guided prostate biopsy for planning of focal salvage after radiation therapy.
abstract: OBJECTIVE
  To determine if the integration of diagnostic magnetic resonance (MR) imaging and MR-guided biopsy would improve target delineation for focal salvage therapy in men with prostate cancer.
  
  
  METHODS
  Between September 2008 and March 2011, 30 men with biochemical failure after radiation therapy for prostate cancer provided written informed consent and were enrolled in a prospective clinical trial approved by the institutional research ethics board. An integrated diagnostic MR imaging and interventional biopsy procedure was performed with a 1.5-T MR imager by using a prototype table and stereotactic transperineal template. Multiparametric MR imaging (T2-weighted, dynamic contrast material-enhanced, and diffusion-weighted sequences) was followed by targeted biopsy of suspicious regions and systematic sextant sampling. Biopsy needle locations were imaged and registered to diagnostic images. Two observers blinded to clinical data and the results of prior imaging studies delineated tumor boundaries. Area under the receiver operating characteristic curve (Az) was calculated based on generalized linear models by using biopsy as the reference standard to distinguish benign from malignant lesions.
  
  
  RESULTS
  Twenty-eight patients were analyzed. Most patients (n = 22) had local recurrence, with 82% (18 of 22) having unifocal disease. When multiparametric volumes from two observers were combined, it increased the apparent overall tumor volume by 30%; however, volumes remained small (mean, 2.9 mL; range, 0.5-8.3 mL). Tumor target boundaries differed between T2-weighted, dynamic contrast-enhanced, and diffusion-weighted sequences (mean Dice coefficient, 0.13-0.35). Diagnostic accuracy in the identification of tumors improved with a multiparametric approach versus a strictly T2-weighted or dynamic contrast-enhanced approach through an improvement in sensitivity (observer 1, 0.65 vs 0.35 and 0.44, respectively; observer 2, 0.82 vs 0.64 and 0.53, respectively; P < .05) and improved further with a 5-mm expansion margin (Az = 0.85 vs 0.91 for observer 2). After excluding three patients with fewer than six informative biopsy cores and six patients with inadequately stained margins, MR-guided biopsy enabled more accurate delineation of the tumor target volume be means of exclusion of false-positive results in 26% (five of 19 patients), false-negative results in 11% (two of 19 patients) and by guiding extension of tumor boundaries in 16% (three of 19 patients).
  
  
  CONCLUSIONS
  The integration of guided biopsy with diagnostic MR imaging is feasible and alters delineation of the tumor target boundary in a substantial proportion of patients considering focal salvage.
authors.affiliation: From the Radiation Medicine Program (C.M., D.I., J.P., J.L., J.A., A.S., W.D.F., M.M., C.C., R.B., A.B., D.A.J., P.C., K.K.B.) and Department of Biostatistics (E.G.A.), Princess Margaret Cancer Centre, 610 University Ave, Room 5-809, Toronto, ON, Canada M4X 1C3; Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada (C.M., D.I., A.S., M.M., C.C., G.M., R.B., A.B., D.A.J., P.C., K.K.B.); Department of Radiation Oncology, Wellington Cancer Centre, Wellington, New Zealand (D.I.), Departments of Anesthesia (G.O.) and Pathology (A.J.E.), University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Radiation Oncology, Odette Cancer Center, Toronto, Ontario, Canada (G.M.); Department of Radiation Oncology, Wellington Cancer Centre, Wellington, New Zealand (D.I.); and Joint Department of Medical Imaging, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada (M.A.H.).
authors.forename: Cynthia
authors.initials: C
authors.lastname: Ménard
authors.forename: Douglas
authors.initials: D
authors.lastname: Iupati
authors.forename: Julia
authors.initials: J
authors.lastname: Publicover
authors.forename: Jenny
authors.initials: J
authors.lastname: Lee
authors.forename: Jessamine
authors.initials: J
authors.lastname: Abed
authors.forename: Gerald
authors.initials: G
authors.lastname: O'Leary
authors.forename: Anna
authors.initials: A
authors.lastname: Simeonov
authors.forename: Warren D
authors.initials: WD
authors.lastname: Foltz
authors.forename: Michael
authors.initials: M
authors.lastname: Milosevic
authors.forename: Charles
authors.initials: C
authors.lastname: Catton
authors.forename: Gerard
authors.initials: G
authors.lastname: Morton
authors.forename: Robert
authors.initials: R
authors.lastname: Bristow
authors.forename: Andrew
authors.initials: A
authors.lastname: Bayley
authors.forename: Eshetu G
authors.initials: EG
authors.lastname: Atenafu
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Evans
authors.forename: David A
authors.initials: DA
authors.lastname: Jaffray
authors.forename: Peter
authors.initials: P
authors.lastname: Chung
authors.forename: Kristy K
authors.initials: KK
authors.lastname: Brock
authors.forename: Masoom A
authors.initials: MA
authors.lastname: Haider
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D061705:Image-Guided Biopsy; D008017:Life Expectancy; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D010347:Patient Care Planning; D011237:Predictive Value of Tests; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy* / Q000601:surgery; D012307:Risk Factors; D016879:Salvage Therapy; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen