FDG-avid presacral soft tissue mass in previously treated rectal cancer: Diagnostic outcome and additional value of MRI, including diffusion-weighted imaging

Jan P. Pennings, Robbert J. de Haas, Kawthar J. A. Murshid, Koert P. de Jong, Rudi A. J. O. Dierckx, Thomas C. Kwee*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Introduction: This study aimed to determine the positive predictive value (PPV) of positron emission tomography/computed tomography (PET/CT) with an F-18-fluoro-2-deoxy-D-glucose (FDG)-avid presacral lesion for locally recurrent rectal cancer, and the additional value of magnetic resonance imaging (MRI), including diffusion-weighted imaging (DWI).

Materials and methods: This retrospective study included 38 patients who completed primary rectal cancer treatment and who presented with a suspicious FDG-avid presacral lesion on PET/CT. Twenty-seven patients also underwent MRI, of whom 24 with DWI. PPV of FOG-PET/CT and additional value of MRI, including DWI, for the diagnosis of recurrent presacral cancer were determined.

Results: The PPV of PET/CT with an FDG-avid presacral lesion for the diagnosis of locally recurrent rectal cancer was 58% (22/38). Air in the FDG-avid presacral lesion, as visible on the a component of the PET/CT examination, favoured the diagnosis of benign presacral tissue with a sensitivity of 56.3% (9/16) and a specificity 81.8% (18/22). Areas under the receiver operating characteristic curve (AUCs) of MRI without DWI for the diagnosis of locally recurrent rectal cancer in FDG-avid presacral tissue were 0.765 and 0.840, for observers 1 and 2. AUCs of MRI with DWI were 0.803 and 0.811, for observers 1 and 2. There were no significant differences among any of these AUCs (P=0.169 to 0.906).

Conclusions: FOG-PET/CT has a poor PPV for locally recurrent rectal cancer in the presacral space. The observation of air in the FDG-avid presacral lesion and additional MRI assessment are diagnostically helpful, without a significant additional value of DWI. (C) 2018 Elsevier Ltd, BASO similar to The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

Original languageEnglish
Pages (from-to)606-612
Number of pages7
Issue number4
Publication statusPublished - Apr-2019


  • 18F-FDG
  • Diffusion MRI
  • PET-CT
  • Magnetic resonance imaging
  • Rectal cancer
  • PET/CT

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