title: Recommendations for MRI-based contouring of gross tumor volume and organs at risk for radiation therapy of pancreatic cancer.
abstract: OBJECTIVE
  Local recurrence is a common and morbid event in patients with unresectable pancreatic adenocarcinoma. A more conformal and targeted radiation dose to the macroscopic tumor in nonmetastatic pancreatic cancer is likely to reduce acute toxicity and improve local control. Optimal soft tissue contrast is required to facilitate delineation of a target and creation of a planning target volume with margin reduction and motion management. Magnetic resonance imaging (MRI) offers considerable advantages in optimizing soft tissue delineation and is an ideal modality for imaging and delineating a gross tumor volume (GTV) within the pancreas, particularly as it relates to conformal radiation planning. Currently, no guidelines have been defined for the delineation of pancreatic tumors for radiation therapy treatment planning. Moreover, abdominal MRI sequences are complex and the anatomy relevant to the radiation oncologist can be challenging. The purpose of this study is to provide recommendations for delineation of GTV and organs at risk (OARs) using MRI and incorporating multiple MRI sequences.
  
  
  METHODS
  Five patients with pancreatic cancer and 1 healthy subject were imaged with MRI scans either on 1.5T or on 3T magnets in 2 separate institutes. The GTV and OARs were contoured for all patients in a consensus meeting.
  
  
  RESULTS
  An overview of MRI-based anatomy of the GTV and OARs is provided. Practical contouring instructions for the GTV and the OARs with the aid of MRI were developed and included in these recommendations. In addition, practical suggestions for implementation of MRI in pancreatic radiation treatment planning are provided.
  
  
  CONCLUSIONS
  With this report, we attempt to provide recommendations for MRI-based contouring of pancreatic tumors and OARs. This could lead to better uniformity in defining the GTV and OARs for clinical trials and in radiation therapy treatment planning, with the ultimate goal of improving local control while minimizing morbidity.
authors.affiliation: Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: H D
authors.initials: HD
authors.lastname: Heerkens
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: W A
authors.initials: WA
authors.lastname: Hall
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: X A
authors.initials: XA
authors.lastname: Li
authors.affiliation: Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: P
authors.initials: P
authors.lastname: Knechtges
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin; Medical Diagnostic Imaging Department, College of Health and Science, University of Sharjah, Sharjah, Dubai.
authors.forename: E
authors.initials: E
authors.lastname: Dalah
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: E S
authors.initials: ES
authors.lastname: Paulson
authors.affiliation: Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: C A T
authors.initials: CAT
authors.lastname: van den Berg
authors.affiliation: Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Meijer
authors.affiliation: Department of Radiation Oncology, MD Anderson Hospital, Houston, Texas.
authors.forename: E J
authors.initials: EJ
authors.lastname: Koay
authors.affiliation: Department of Radiation Oncology, MD Anderson Hospital, Houston, Texas.
authors.forename: C H
authors.initials: CH
authors.lastname: Crane
authors.affiliation: Department of Radiation Oncology, Royal Marsden Hospital London, England.
authors.forename: K
authors.initials: K
authors.lastname: Aitken
authors.affiliation: Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: van Vulpen
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin. Electronic address: berickson@mcw.edu.
authors.forename: B A
authors.initials: BA
authors.lastname: Erickson
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D009367:Neoplasm Staging; D058958:Organs at Risk / Q000000981:diagnostic imaging; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D017410:Practice Guidelines as Topic; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden; D055815:Young Adult