Advances in Radiation Oncology (Oct 2019)

Gross Tumor Delineation in Esophageal Cancer on MRI Compared With 18F-FDG-PET/CT

  • Sophie E. Vollenbrock, MD,
  • Marlies E. Nowee, MD, PhD,
  • Francine E.M. Voncken, MD,
  • Alexis N.T.J. Kotte, PhD,
  • Lucas Goense, MD, PhD,
  • Peter S.N. van Rossum, MD, PhD,
  • Astrid L.H.M.W. van Lier, PhD,
  • Stijn W. Heijmink, MD, PhD,
  • Annemarieke Bartels-Rutten, MD, PhD,
  • Frank J. Wessels, MD,
  • Berthe M.P. Aleman, MD, PhD,
  • Luc Dewit, MD, PhD,
  • Linda G.W. Kerkmeijer, MD, PhD,
  • Edwin P.M. Jansen, MD, PhD,
  • Martijn Intven, MD, PhD,
  • Irene M. Lips, MD, PhD,
  • Gert J. Meijer, PhD,
  • Jasper Nijkamp, PhD

Journal volume & issue
Vol. 4, no. 4
pp. 596 – 604

Abstract

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Purpose: Current delineation of the gross tumor volume (GTV) in esophageal cancer relies on computed tomography (CT) and combination with 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). There is increasing interest in integrating magnetic resonance imaging (MRI) in radiation treatment, which can potentially obviate CT- or FDG-PET/CT–based delineation. The aim of this study is to evaluate the feasibility of target delineation on T2-weighted (T2W) MRI and T2W including diffusion-weighted MRI (T2W + DW-MRI) compared with current-practice FDG-PET/CT. Methods: Ten observers delineated primary esophageal tumor GTVs of 6 patients on FDG-PET/CT, T2W-MRI, and T2W + DW-MRI. GTVs, generalized conformity indices, in-slice delineation variation (root mean square), and standard deviations in the position of the most cranial and caudal delineated slice were calculated. Results: Delineations on MRI showed smaller GTVs compared with FDG-PET/CT–based delineations. The main variation was seen at the cranial and caudal border. No differences were observed in conformity indices (FDG-PET/CT, 0.68; T2W-MRI, 0.66; T2W + DW-MRI, 0.68) and in-slice variation (root mean square, 0.13 cm on FDG-PET/CT; 0.10 cm on T2W-MRI; 0.14 cm on T2W + DW-MRI). In the 2 tumors involving the gastroesophageal junction, addition of DW-MRI to T2W-MRI significantly decreased caudal border variation. Conclusions: MRI-based target delineation of the esophageal tumor is feasible with interobserver variability comparable to that with FDG-PET/CT, despite limited experience with delineation on MRI. Most variation was seen at cranial-caudal borders, and addition of DW-MRI to T2W-MRI may reduce caudal delineation variation of gastroesophageal junction tumors.