Recommendations for MRI-based contouring of gross tumor volume and organs at risk for radiotherapy of pancreatic cancer

Publication date: Available online 17 October 2016
Source:Practical Radiation Oncology
Author(s): H.D. Heerkens, W.A. Hall, X.A. Li, P. Knechtges, E. Dalah, E.S. Paulson, C.A.T. van den Berg, G.J. Meijer, E.J. Koay, C.H. Crane, K. Aitken, M. van Vulpen, B.A. Erickson
PurposeLocal 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 non-metastatic 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. MRI offers considerable advantages in optimizing soft tissue delineation and is an ideal modality for imaging and delineating a gross tumor volume within the pancreas, particularly as it relates to conformal radiation planning. Currently, no guidelines have been defined for the delineation of pancreatic tumors for radiotherapy 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 gross tumor volume (GTV) and organs at risk (OARs) using MRI and incorporating multiple MRI sequences.MethodsFive pancreatic cancer patients and one healthy subject were imaged with MRI either on 1.5T or on 3T magnets in two separate institutes. The GTV and OARs were contoured for all patients in a consensus meeting.ResultsAn 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.ConclusionsWith this report we attempt to provide recommendations for MRI-based contouring of pancreatic tumors and organs at risk. This could lead to better uniformity in defining the GTV and OARs for clinical trials and in radiotherapy treatment planning with the ultimate goal of improving local control while minimizing morbidity.SummaryThese recommendations describe the contouring of pancreatic tumors and organs at risk (OAR) using MRI. Practical contouring instructions for the gross tumor volume and OAR are provided based on five pancreatic cancer patients and one healthy subject. This report provides recommendations on how to integrate MRI into radiation treatment planning for pancreatic tumors and addresses the potential challenges of MRI.



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