title: T-staging of rectal cancer: accuracy of 3.0 Tesla MRI compared with 1.5 Tesla.
abstract: OBJECTIVE
  Magnetic resonance imaging (MRI) is not accurate in discriminating T1-2 from borderline T3 rectal tumors. Higher resolution on 3 Tesla-(3T)-MRI could improve diagnostic performance for T-staging. The aim of this study was to determine whether 3T-MRI compared with 1.5 Tesla-(1.5T)-MRI improves the accuracy for the discrimination between T1-2 and borderline T3 rectal tumors and to evaluate reproducibility.
  
  
  METHODS
  13 patients with non-locally advanced rectal cancer underwent imaging with both 1.5T and 3T-MRI. Three readers with different expertise evaluated the images and predicted T-stage with a confidence level score. Receiver operator characteristics curves with areas under the curve (AUC) and diagnostic parameters were calculated. Inter- and intra-observer agreements were calculated with quadratic kappa-weighting. Histology was the reference standard.
  
  
  RESULTS
  Seven patients had pT1-2 tumors and six had pT3 tumors. AUCs ranged from 0.66 to 0.87 at 1.5T vs. 0.52-0.82 at 3T. Mean overstaging rate was 43% at 1.5T and 57% at 3T (P = 0.23). Inter-observer agreement was κ 0.50-0.71 at 1.5T vs. 0.15-0.68 at 3T. Intra-observer agreement was κ 0.71 at 1.5T and 0.76 at 3T.
  
  
  CONCLUSIONS
  This is the first study to compare 3T with 1.5T MRI for T-staging of rectal cancer within the same patients. Our results showed no difference between 3T and 1.5T-MRI for the distinction between T1-2 and borderline T3 tumors, regardless of expertise. The higher resolution at 3T-MRI did not aid in the distinction between desmoplasia in T1-2-tumors and tumor stranding in T3-tumors. Larger studies are needed to acknowledge these findings.
authors.affiliation: Department of Radiology, Maastricht University Medical Center, AZ, The Netherlands.
authors.forename: Monique
authors.initials: M
authors.lastname: Maas
authors.forename: Doenja M J
authors.initials: DM
authors.lastname: Lambregts
authors.forename: Max J
authors.initials: MJ
authors.lastname: Lahaye
authors.forename: Geerard L
authors.initials: GL
authors.lastname: Beets
authors.forename: Walter
authors.initials: W
authors.lastname: Backes
authors.forename: Roy F A
authors.initials: RF
authors.lastname: Vliegen
authors.forename: Margreet
authors.initials: M
authors.lastname: Osinga-de Jong
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
authors.forename: Regina G H
authors.initials: RG
authors.lastname: Beets-Tan
mesh_terms: D019540:Area Under Curve; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy