title: Lessons learned using an MRI-only workflow during high-dose-rate brachytherapy for prostate cancer.
abstract: OBJECTIVE
  We report clinical observations of a technique using an MRI-only workflow for catheter insertion and treatment planning in patients receiving standard-care high-dose-rate brachytherapy before external beam radiotherapy for prostate cancer.
  
  
  METHODS
  Forty patients with intermediate or high-risk prostate cancer were enrolled on a prospective clinical trial approved by our institution's research ethics board. Multiparametric MRI with stereotactic navigation was used to guide insertion of brachytherapy catheters, followed by MRI-based treatment planning.
  
  
  RESULTS
  Sixty-two implants were performed. Median catheter insertion + imaging time was 100 minutes, and overall anesthesia time was 4.0 hours (range, 2.1-6.9 hours). MRI at the time of brachytherapy restaged 14 patients (35%) who were found to have a higher stage of disease. In 6 patients, this translated in directed insertion of brachytherapy catheters outside the prostate boundary (extracapsular disease [n = 2] or seminal vesicle invasion [n = 4]). Most patients (80%) had gross tumor visible on MRI, which influenced catheter insertion and treatment planning. MRI depicted postimplant anatomic boundaries clearly, with the exception of the apical prostate which was blurred by trauma after catheter insertion. Conventional dose-planning objectives for the rectum (V75 < 1.0 cc) were difficult to achieve, but toxicities were low (acute grade ≥ 2 genitourinary = 20%, late grade ≥ 2 genitourinary = 15%, and late grade ≥ 2 gastrointestinal = 7%). Urethral trauma visualized on MRI led to two transient Grade 3 events.
  
  
  CONCLUSIONS
  Despite a standard-care approach, MRI acquired throughout the procedure altered catheter insertion and dose-planning strategies. An MRI-only workflow is feasible but must be streamlined for broader acceptance.
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Jure
authors.initials: J
authors.lastname: Murgic
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Chung
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Berlin
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Bayley
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Padraig
authors.initials: P
authors.lastname: Warde
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Catton
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: Simeonov
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada.
authors.forename: Jessamine
authors.initials: J
authors.lastname: Abed
authors.affiliation: University Health Network, Department of Anesthesia, University of Toronto, Toronto, ON, Canada.
authors.forename: Gerald
authors.initials: G
authors.lastname: O'Leary
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rink
authors.affiliation: Radiation Medicine Program, Princess Margaret Cancer Centre/University Health Network, Toronto, ON, Canada; Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada; Département de radio-oncologie, Centre hospitalier de l'Université de Montréal (CHUM), Montréal, QC, Canada. Electronic address: cynthia.menard@umontreal.ca.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Ménard
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D002404:Catheterization / Q000009:adverse effects; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum / Q000528:radiation effects; D013997:Time Factors; D014521:Urethra / Q000293:injuries; D014566:Urogenital System; D057188:Workflow
keywords: HDR brachytherapy; MRI; Prostate cancer