title: Rectal cancer in inflammatory bowel diseases: MR imaging findings.
abstract: OBJECTIVE
  To retrospectively analyze the MR imaging features of rectal cancer in patients with inflammatory bowel diseases (IBD).
  
  
  METHODS
  The MR imaging examinations of 13 patients with IBD-related rectal cancer were retrospectively reviewed. MR imaging included T2-weighted, diffusion-weighted (DW), and gadolinium chelate-enhanced MR imaging. MR imaging findings were analyzed and compared with endoscopic and histopathological findings.
  
  
  RESULTS
  Eight patients (8/13; 62%) had active IBD and five (5/13; 38%) had quiescent IBD on MR imaging. Two different tumor patterns were individualized including clearly visible soft-tissue mass (4/13; 31%) (Type 1 tumor) and marked circumferential rectal wall thickening (9/13; 69%) (Type 2 tumor). Twelve tumors (12/13; 92%) showed high signal intensity on T2-weighted MR images. All six tumors studied with DW-MR imaging (6/6; 100%) showed high signal on DW-MR imaging with restricted diffusion on apparent diffusion coefficient (ADC) map. On gadolinium chelate-enhanced MR imaging, heterogeneous enhancement was observed in one tumor (1/13; 8%), whereas 12 tumors (12/13; 92%) showed homogeneous enhancement. MR imaging showed pelvic fistula and intrapelvic abscess in association with four (4/13; 31%) and two tumors (2/13; 15%), respectively.
  
  
  CONCLUSIONS
  Our limited retrospective study demonstrates that rectal cancer in IBD patients can present as a circumferential wall thickening resembling inflammation and can occur in the absence of fistula or abscess. The use of T2-weighted and DW-MR imaging is recommended to improve rectal cancer detection in patients with long-standing IBD.
authors.affiliation: Department of Abdominal Imaging, Hôpital Lariboisière, Assistance Publique-Hôpitaux de Paris, 2 rue Ambroise Paré, 75010, Paris, France, matthias_barral@yahoo.fr.
authors.forename: Matthias
authors.initials: M
authors.lastname: Barral
authors.forename: Christine
authors.initials: C
authors.lastname: Hoeffel
authors.forename: Mourad
authors.initials: M
authors.lastname: Boudiaf
authors.forename: Anthony
authors.initials: A
authors.lastname: Dohan
authors.forename: Philippe
authors.initials: P
authors.lastname: Marteau
authors.forename: Valérie
authors.initials: V
authors.lastname: Laurent
authors.forename: Philippe
authors.initials: P
authors.lastname: Soyer
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D015212:Inflammatory Bowel Diseases / Q000150:complications* / Q000473:pathology*; D008297:Male; D008536:Meglumine; D008875:Middle Aged; D009942:Organometallic Compounds; D012004:Rectal Neoplasms / Q000150:complications* / Q000175:diagnosis* / Q000473:pathology; D012007:Rectum / Q000473:pathology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D008536:Meglumine; C072417:gadoterate meglumine