Improving staging of rectal cancer in the pelvis: the role of PET/MRI

Onofrio A. Catalano, Susanna I. Lee, Chiara Parente, Christy Cauley, Felipe S. Furtado, Robin Striar, Andrea Soricelli, Marco Salvatore, Yan Li, Lale Umutlu, Lina Garcia Cañamaque, David Groshar, Umar Mahmood, Lawrence S. Blaszkowsky, David P. Ryan, Jeffrey W. Clark, Jennifer Wo, Theodore S. Hong, Hiroko Kunitake, Liliana BordeianouDavid Berger, Rocco Ricciardi, Bruce Rosen

Research output: Contribution to journalArticlepeer-review


Purpose: The role of positron emission tomography/magnetic resonance (PET/MR) in evaluating the local extent of rectal cancer remains uncertain. This study aimed to investigate the possible role of PET/MR versus magnetic resonance (MR) in clinically staging rectal cancer. Methods: This retrospective two-center cohort study of 62 patients with untreated rectal cancer investigated the possible role of baseline staging PET/MR versus stand-alone MR in determination of clinical stage. Two readers reviewed T and N stage, mesorectal fascia involvement, tumor length, distance from the anal verge, sphincter involvement, and extramural vascular invasion (EMVI). Sigmoidoscopy, digital rectal examination, and follow-up imaging, along with surgery when available, served as the reference standard. Results: PET/MR outperformed MR in evaluating tumor size (42.5 ± 21.03 mm per the reference standard, 54 ± 20.45 mm by stand-alone MR, and 44 ± 20 mm by PET/MR, P = 0.004), and in identifying N status (correct by MR in 36/62 patients [58%] and by PET/MR in 49/62 cases [79%]; P = 0.02) and external sphincter infiltration (correct by MR in 6/10 and by PET/MR in 9/10; P = 0.003). No statistically significant differences were observed in relation to any other features. Conclusion: PET/MR provides a more precise assessment of the local extent of rectal cancers in evaluating cancer length, N status, and external sphincter involvement. PET/MR offers the opportunity to improve clinical decision-making, especially when evaluating low rectal tumors with possible external sphincter involvement.

Original languageEnglish
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Publication statusAccepted/In press - 2020


  • MRI
  • PET
  • PET/MR
  • Rectal cancer
  • Staging

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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