title: Image Guided Focal Therapy for Magnetic Resonance Imaging Visible Prostate Cancer: Defining a 3-Dimensional Treatment Margin Based on Magnetic Resonance Imaging Histology Co-Registration Analysis.
abstract: OBJECTIVE
  We compared prostate tumor boundaries on magnetic resonance imaging and radical prostatectomy histological assessment using detailed software assisted co-registration to define an optimal treatment margin for achieving complete tumor destruction during image guided focal ablation.
  
  
  METHODS
  Included in study were 33 patients who underwent 3 Tesla magnetic resonance imaging before radical prostatectomy. A radiologist traced lesion borders on magnetic resonance imaging and assigned a suspicion score of 2 to 5. Three-dimensional reconstructions were created from high resolution digitalized slides of radical prostatectomy specimens and co-registered to imaging using advanced software. Tumors were compared between histology and imaging by the Hausdorff distance and stratified by the magnetic resonance imaging suspicion score, Gleason score and lesion diameter. Cylindrical volume estimates of treatment effects were used to define the optimal treatment margin.
  
  
  RESULTS
  Three-dimensional software based registration with magnetic resonance imaging was done in 46 histologically confirmed cancers. Imaging underestimated tumor size with a maximal discrepancy between imaging and histological boundaries for a given tumor of an average ± SD of 1.99 ± 3.1 mm, representing 18.5% of the diameter on imaging. Boundary underestimation was larger for lesions with an imaging suspicion score 4 or greater (mean 3.49 ± 2.1 mm, p <0.001) and a Gleason score of 7 or greater (mean 2.48 ± 2.8 mm, p = 0.035). A simulated cylindrical treatment volume based on the imaging boundary missed an average 14.8% of tumor volume compared to that based on the histological boundary. A simulated treatment volume based on a 9 mm treatment margin achieved complete histological tumor destruction in 100% of patients.
  
  
  CONCLUSIONS
  Magnetic resonance imaging underestimates histologically determined tumor boundaries, especially for lesions with a high imaging suspicion score and a high Gleason score. A 9 mm treatment margin around a lesion visible on magnetic resonance imaging would consistently ensure treatment of the entire histological tumor volume during focal ablative therapy.
authors.affiliation: Division of Urologic Oncology, Department of Urology, New York University Langone Medical Center, New York, New York; Departments of Urology, University Hospital of Lille, Lille and Unités Mixtes de Recherche 6301-CERVOxy Group, University Hospital of Caen, Caen, France. Electronic address: julien.lenobin@gmail.com.
authors.forename: Julien
authors.initials: J
authors.lastname: Le Nobin
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, New York.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.affiliation: Departments of Urology, University Hospital of Lille, Lille and Unités Mixtes de Recherche 6301-CERVOxy Group, University Hospital of Caen, Caen, France.
authors.forename: Arnauld
authors.initials: A
authors.lastname: Villers
authors.affiliation: Division of Urologic Oncology, Department of Urology, New York University Langone Medical Center, New York, New York.
authors.forename: Clément
authors.initials: C
authors.lastname: Orczyk
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Fang-Ming
authors.initials: FM
authors.lastname: Deng
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Melamed
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, New York.
authors.forename: Artem
authors.initials: A
authors.lastname: Mikheev
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, New York.
authors.forename: Henry
authors.initials: H
authors.lastname: Rusinek
authors.affiliation: Division of Urologic Oncology, Department of Urology, New York University Langone Medical Center, New York, New York.
authors.forename: Samir S
authors.initials: SS
authors.lastname: Taneja
mesh_terms: D000368:Aged; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011467:Prostate / Q000473:pathology* / Q000601:surgery; D011468:Prostatectomy / Q000379:methods*; D011471:Prostatic Neoplasms / Q000473:pathology / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome; D047368:Tumor Burden
keywords: computer-assisted; image processing; magnetic resonance imaging; pathology; prostatic neoplasms; risk