title: T staging of rectal cancer: accuracy of diffusion-weighted imaging compared with T2-weighted imaging on 3.0 tesla MRI.
abstract: OBJECTIVE
  To evaluate the performance of diffusion-weighted imaging (DWI) in the T staging of primary rectal cancer compared with T2-weighted (T2W) fast spin-echo imaging using 3.0 tesla magnetic resonance imaging (MRI).
  
  
  METHODS
  In total, 46 consecutive patients with rectal cancer who underwent MRI examination before surgery were included in the study. The diagnostic accuracy, sensitivity and specificity of DWI and T2W imaging (T2WI) for T staging of the tumors were evaluated, and interobserver agreement between the two radiologists was calculated.
  
  
  RESULTS
  The diagnostic accuracies of DWI and T2WI for the T staging of rectal cancer were 73.9% and 71.7%, respectively. The sensitivity and specificity of DWI were 90.0% and 88.9% for diagnosing T1 tumors, 64.3% and 87.5% for T2 tumors, 77.8% and 89.3% for T3 tumors and 50.0% and 97.6% for T4 tumors, respectively; while the sensitivity and specificity of T2WI were 80.0% and 91.7% for T1 tumors, 64.3% and 78.1% for T2 tumors, 77.8% and 89.3% for T3 tumors and 50.0% and 100% for T4 tumors, respectively. There were no significant differences in the diagnostic accuracy, sensitivity or specificity between DWI and T2WI no matter what kind of T stage was concerned (P > 0.05). The interobserver agreement was 0.74 for DWI and 0.63 for T2WI.
  
  
  CONCLUSIONS
  DWI can be applied as a useful tool for evaluating the T staging of rectal cancer. The interobserver agreement obtained by using DWI is better than that obtained by using T2WI.
authors.affiliation: Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Feng
authors.forename: Yun Qi
authors.initials: YQ
authors.lastname: Yan
authors.forename: Jiong
authors.initials: J
authors.lastname: Zhu
authors.forename: Jian Rong
authors.initials: JR
authors.lastname: Xu
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015588:Observer Variation; D012004:Rectal Neoplasms / Q000473:pathology*; D012680:Sensitivity and Specificity
keywords: diffusion-weighted imaging; magnetic resonance imaging; neoplasm staging; rectal neoplasms; sensitivity and specificity