FDG-PET/MRI for Nonoperative Management of Rectal Cancer: A Prospective Pilot Study

Semra Ince, Malak Itani, Lauren E. Henke, Radhika K. Smith, Paul E. Wise, Matthew G. Mutch, Sean C. Glasgow, Matthew L. Silviera, Katrina S. Pedersen, Steven R. Hunt, Hyun Kim, Tyler J. Fraum

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5 Scopus citations


Nonoperative management (NOM) is increasingly utilized for rectal cancer patients with a clinical complete response (cCR) following total neoadjuvant therapy (TNT). The objective of this pilot study was to determine whether FDG-PET/MRI alters clinical response assessments among stage I-III rectal cancer patients undergoing TNT followed by NOM, relative to MRI alone. This prospective study included 14 subjects with new rectal cancer diagnoses. Imaging consisted of FDG-PET/MRI for initial staging, post-TNT restaging, and surveillance during NOM. Two independent readers assessed treatment response on MRI followed by FDG-PET/MRI. Inter-reader differences were resolved by consensus review. The reference standard for post-TNT restaging consisted of surgical pathology or clinical follow-up. 7/14 subjects completed post-TNT restaging FDG-PET/MRIs. 5/7 subjects had evidence of residual disease and underwent total mesorectal excision; 2/7 subjects had initial cCR with no evidence of disease after 12 months of NOM. FDG-PET/MRI assessments of cCR status at post-TNT restaging had an accuracy of 100%, compared with 71% for MRI alone, as FDG-PET detected residual tumor in 2 more subjects. Inter-reader agreement for cCR status on FDG-PET/MRI was moderate (kappa, 0.56). FDG-PET provided added value in 82% (9/11) of restaging/surveillance scans. Our preliminary data indicate that FDG-PET/MRI can detect more residual disease after TNT than MRI alone, with the FDG-PET component providing added value in most restaging/surveillance scans.

Original languageEnglish
Pages (from-to)2723-2734
Number of pages12
JournalTomography (Ann Arbor, Mich.)
Issue number6
StatePublished - Dec 2022


  • nonoperative management
  • rectal cancer


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