title: Mucinous versus nonmucinous rectal carcinomas: differentiation with MR imaging.
abstract: OBJECTIVE
  To determine if quantitative and qualitative magnetic resonance (MR) imaging measures can help differentiation of mucinous from nonmucinous rectal tumors.
  
  
  METHODS
  In 26 patients with pathologically proved mucinous (n = 9) and nonmucinous (n = 17) rectal tumors, MR imaging was performed with T1-weighted spin-echo (SE) and T2-weighted fast SE sequences in all patients and with a gadolinium-enhanced T1-weighted sequence in 18. With use of the signal intensity (SI) measurements in the tumors and reference tissues, tumor-to-muscle, tumor-to-fat, and tumor-to-urine SI ratios were calculated. In addition, the SI and contrast-enhancement patterns in the tumors were assessed qualitatively by three blinded readers.
  
  
  RESULTS
  Mucinous tumors had a much higher SI on the T2-weighted fast SE images. Tumor-to-muscle, tumor-to-fat, and tumor-to-urine SI ratios were significantly higher in the mucinous compared with the nonmucinous tumors (P = .0004, P = .0008, and P = .00002, respectively). Qualitative evaluation of the SI correlated well between readers 1 and 2 (r = 0.93), readers 1 and 3 (r = 0.94), and readers 2 and 3 (r = 0.91). Agreement for the contrast-enhancement patterns was 67%, 72%, and 67%, respectively, with most mucinous tumors having predominantly high SI and a peripheral contrast-enhancement pattern.
  
  
  CONCLUSIONS
  Mucinous and nonmucinous rectal tumors can be differentiated with MR imaging because mucinous tumors show high SI on T2-weighted fast SE images.
authors.affiliation: Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, Pa., USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Hussain
authors.forename: E K
authors.initials: EK
authors.lastname: Outwater
authors.forename: E S
authors.initials: ES
authors.lastname: Siegelman
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000175:diagnosis* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D012007:Rectum / Q000473:pathology; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA